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                                                                   EXHIBIT 10.1


                                                                 EXECUTION COPY


                          SECURITIES PURCHASE AGREEMENT

        SECURITIES PURCHASE AGREEMENT (this "AGREEMENT"), dated as of June 29,
2001, between ViroLogic, Inc., a corporation organized under the laws of the
State of Delaware (the "COMPANY"), and each of the purchasers (individually, a
"PURCHASER" and collectively the "PURCHASERS") set forth on the execution pages
hereof (the "EXECUTION PAGES, and each an "EXECUTION PAGE").

        WHEREAS:

        A. The Company and each Purchaser are executing and delivering this
Agreement in reliance upon the exemption from securities registration afforded
by the provisions of Regulation D ("REGULATION D"), as promulgated by the United
States Securities and Exchange Commission (the "SEC") under the Securities Act
of 1933, as amended (the "SECURITIES ACT").

        B. The Company desires to sell, and each Purchaser desires to purchase,
at each of two Closings, upon the terms and conditions stated in this Agreement,
units (the "UNITS"), each Unit consisting of (i) one share of the Company's
Series A Convertible Preferred Stock, par value $.001 per share (the "PREFERRED
SHARES"), convertible into approximately 3,921.569 shares of the Company's
common stock, par value $.001 per share (the "COMMON STOCK"), and (ii) a
warrant, in the form attached hereto as Exhibit B (the "WARRANTS"), to acquire
approximately 1,960.784 shares of Common Stock. The rights, preferences and
privileges of the Preferred Shares, including the terms upon which such
Preferred Shares are convertible into shares of Common Stock, are set forth in
the form of Certificate of Designations, Preferences and Rights attached hereto
as Exhibit A (the "CERTIFICATE OF DESIGNATION"). The shares of Common Stock
issuable upon conversion of the Preferred Shares or otherwise pursuant to the
Certificate of Designation are referred to herein as the "CONVERSION SHARES" and
the shares of Common Stock issuable upon exercise of or otherwise pursuant to
the Warrants are referred to herein as the "WARRANT SHARES." The Preferred
Shares, the Warrants, the Conversion Shares and the Warrant Shares are
collectively referred to herein as the "SECURITIES" and each of them may
individually be referred to herein as a "SECURITY."

        C. Contemporaneous with the execution and delivery of this Agreement,
the parties hereto are executing and delivering two Registration Rights
Agreements, in the forms attached hereto as Exhibit C (the "FIRST REGISTRATION
RIGHTS AGREEMENT," and the "SECOND REGISTRATION RIGHTS AGREEMENT," respectively,
and, collectively, the "REGISTRATION RIGHTS AGREEMENTS"), pursuant to which the
Company has agreed to provide certain registration rights under the Securities
Act and the rules and regulations promulgated thereunder, and applicable state
securities laws.


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        NOW, THEREFORE, the Company and the Purchasers hereby agree as follows:

1.      PURCHASE AND SALE OF UNITS.

        (a) Purchase of Units. The issuance, sale and purchase of the Units
shall take place in two separate closings, the first of which is referred to
herein as the "FIRST CLOSING" and the second of which is referred to herein as
the "SECOND CLOSING".

            (i) On the First Closing Date (as defined below), subject to the
satisfaction (or waiver) of the conditions set forth in Section 6 and Section 7
below, the Company shall issue and sell to each Purchaser, and each Purchaser
agrees to purchase from the Company, such number of Units as is set forth on
such Purchaser's Execution Page attached hereto. The purchase price (the
"PURCHASE PRICE") per Unit shall be equal to Ten Thousand Dollars ($10,000).
Notwithstanding anything to the contrary contained herein, in no event will the
Company be obligated to issue at the First Closing more than the maximum number
of Units permissible under Rule 4350(i) of the National Association of
Securities Dealers, Inc. ("NASD") without stockholder approval. Any Units
subscribed for but unissued at the First Closing due to the preceding sentence
shall be allocated pro rata among the Purchasers based on the total number of
Units being purchased in the aggregate at the First Closing and Second Closing
compared to each Purchaser's percentage thereof, and such Units shall be
purchased and issued at the Second Closing.

            (ii) On the Second Closing Date (as defined below), subject to the
satisfaction (or waiver) of the conditions set forth in Section 6 and Section 7
below, the Company shall issue and sell to each Purchaser, and each Purchaser
agrees to purchase from the Company such number of Units as is set forth on such
Purchaser's Execution Page attached hereto.

        (b) Form of Payment. On the First Closing Date, each Purchaser shall pay
the applicable purchase price by wire transfer to the Company in accordance with
the Company's written wiring instructions, against delivery of the Units being
purchased at the First Closing by such Purchaser, and the Company shall deliver
such Units against delivery of the applicable purchase price; and, if
applicable, on the Second Closing Date, each Purchaser shall pay the applicable
purchase price by wire transfer to the Company in accordance with the Company's
written wiring instructions, against delivery of the Units being purchased at
the Second Closing, by such Purchaser and the Company shall deliver such Units
against delivery of the applicable purchase price.

        (c) Closing Date. Subject to the satisfaction (or waiver) of the
conditions thereto set forth in Section 6 and Section 7 below, the date and time
of the issuance and sale of the Units to each of the Purchasers pursuant to this
Agreement at the First Closing shall be 12:00 noon, New York City time, on June
29, 2001, subject to a two business day grace period at either party's



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option, but in any event not later than July 3, 2001, or such other time as may
be mutually agreed upon by the Company and the Purchasers purchasing a majority
of the Units at the First Closing (the "FIRST CLOSING DATE"), and the time and
date of the issuance and sale of the Units to each Purchaser pursuant to this
Agreement at the Second Closing shall be 12:00 noon, New York City time, on the
third (3) business day after either party has delivered written notice to the
other party of the satisfaction (or waiver, if applicable) of the conditions in
Section 6(b) and Section 7(b) hereof, or at such other date and time as may be
mutually agreed upon by the Company and the Purchasers purchasing a majority of
the Units at the Second Closing (the "SECOND CLOSING DATE"). The First Closing
and the Second Closing shall occur at the offices of Klehr, Harrison, Harvey,
Branzburg & Ellers LLP, 260 South Broad Street, Philadelphia, PA 19102-5003

2.      PURCHASER'S REPRESENTATIONS AND WARRANTIES. Each Purchaser severally,
but not jointly, represents and warrants to the Company as follows:

        (a) Purchase for Own Account, Etc.. Such Purchaser is purchasing the
Units for such Purchaser's own account and not with a present view towards the
public sale or distribution thereof, except pursuant to sales that are exempt
from the registration requirements of the Securities Act and/or sales registered
under the Securities Act. Such Purchaser understands that Purchaser must bear
the economic risk of this investment indefinitely, unless the Securities are
registered pursuant to the Securities Act and any applicable state securities or
blue sky laws or an exemption from such registration is available, and that the
Company has no present intention of registering the resale of any such
Securities other than as contemplated by the Registration Rights Agreements.
Notwithstanding anything in this Section 2(a) to the contrary, by making the
representations herein, the Purchaser does not agree to hold the Securities for
any minimum or other specific term and reserves the right to dispose of the
Securities at any time in accordance with or pursuant to a registration
statement or an exemption from the registration requirements under the
Securities Act.

        (b) Accredited Investor Status. Such Purchaser is an "ACCREDITED
INVESTOR" as that term is defined in Rule 501(a) of Regulation D under the
Securities Act; the Purchaser is also knowledgeable, sophisticated and
experienced in making, and is qualified to make decisions with respect to,
investments in shares presenting an investment decision like that involved in
the purchase of the Units, including investments in securities issued by the
Company and investments in comparable companies; and the Purchaser has
requested, received, reviewed and considered all information it deems relevant
in making an informed decision to purchase the Units.

        (c) Reliance on Exemptions. Such Purchaser understands that the Units
are being offered and sold to such Purchaser in reliance upon specific
exemptions from the registration requirements of United States federal and state
securities laws and that the Company is relying upon the truth and accuracy of,
and such Purchaser's compliance with, the representations,


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warranties, agreements, acknowledgments and understandings of such Purchaser set
forth herein in order to determine the availability of such exemptions and the
eligibility of such Purchaser to acquire the Securities.

        (d) Information. Such Purchaser and its counsel, if any, have been
furnished all materials relating to the business, finances and operations of the
Company and materials relating to the offer and sale of the Securities which
have been specifically requested by such Purchaser or its counsel. Such
Purchaser and its counsel have been afforded the opportunity to ask questions of
the Company and have received what such Purchaser believes to be satisfactory
answers to any such inquiries. Neither such inquiries nor any other
investigation conducted by such Purchaser or its counsel or any of its
representatives shall modify, amend or affect such Purchaser's right to rely on
the Company's representations and warranties contained in Section 3 below. Such
Purchaser understands that such Purchaser's investment in the Securities
involves a high degree of risk.

        (e) Governmental Review. Such Purchaser understands that no United
States federal or state agency or any other government or governmental agency
has passed upon or made any recommendation or endorsement of the Securities.

        (f) Transfer or Resale. Such Purchaser understands that (i) except as
provided in the Registration Rights Agreements, the sale or resale of the
Securities have not been and are not being registered under the Securities Act
or any state securities laws, and the Securities may not be transferred unless
(a) the transfer is made pursuant to and as set forth in an effective
registration statement under the Securities Act covering the Securities; or (b)
such Purchaser shall have delivered to the Company an opinion of counsel (which
opinion shall be in form, substance and scope customary for opinions of counsel
in comparable transactions) to the effect that the Securities to be sold or
transferred may be sold or transferred pursuant to an exemption from such
registration; or (c) sold under and in compliance with Rule 144 promulgated
under the Securities Act (or a successor rule) ("RULE 144"); or (d) sold or
transferred in accordance with applicable securities laws to an affiliate of
such Purchaser who agrees to sell or otherwise transfer the Securities only in
accordance with the provisions of this Section 2(f) and who is an Accredited
Investor; and (ii) neither the Company nor any other person is under any
obligation to register such Securities under the Securities Act or any state
securities laws (other than pursuant to the Registration Rights Agreements).
Notwithstanding the foregoing or anything else contained herein to the contrary,
the Securities may be pledged as collateral in connection with a bona fide
margin account or other lending arrangement, provided such pledge is consistent
with applicable laws, rules and regulations.

        (g) Legends. Such Purchaser understands that the certificates for the
Preferred Shares, Warrants and, until such time as the Conversion Shares and
Warrant Shares have been registered under the Securities Act (including
registration pursuant to Rule 416 thereunder) as


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contemplated by the Registration Rights Agreements or otherwise may be sold by
such Purchaser under Rule 144(k), the certificates for the Conversion Shares and
Warrant Shares shall bear a restrictive legend in substantially the following
form:

                The securities represented by this certificate have not been
                registered under the Securities Act of 1933, as amended, or the
                securities laws of any state of the United States or in any
                other jurisdiction. The securities represented hereby may not be
                offered, sold or transferred in the absence of an effective
                registration statement for the securities under applicable
                securities laws unless offered, sold or transferred pursuant to
                an available exemption from the registration requirements of
                those laws.

        The Company agrees that it shall, immediately prior to the initial
registration statement (to be filed pursuant to Section 2(a) of the Registration
Rights Agreements) being declared effective, instruct its transfer agent (and
provide such transfer agent with any additional documentation that may be
necessary to accomplish the following) that at any time the Registration
Statement is effective, and assuming compliance with the applicable provisions
of the Certificate of Designation or the Warrant, as applicable, the transfer
agent shall issue, in connection with the issuance of the Conversion Shares and
Warrant Shares, certificates representing such Conversion Shares and Warrant
Shares without the restrictive legend above, provided such Conversion Shares and
Warrant Shares are to be sold pursuant to the prospectus contained in the
Registration Statement. At such time, the Company shall cause the transfer agent
to confirm, for the benefit of the holders, that no further documentation will
be required at the time of transfer, conversion or exercise, as applicable, of
such shares in order to issue such shares without such restrictive legend. The
parties acknowledge that the Company has certain rights with respect to
transfers of the Securities as set forth in the Registration Rights Agreements.

        The legend set forth above shall be removed and the Company shall issue
a certificate without such legend to the holder of any Security upon which it is
stamped, if, unless otherwise required by state securities laws, (a) the sale of
such Security is registered under the Securities Act (including registration
pursuant to Rule 416 thereunder) as contemplated by the Registration Rights
Agreements and the Security is sold pursuant to and as set forth in such
Registration Statement and in the Securities Act; (b) such holder provides the
Company with an opinion of counsel, in form, substance and scope customary for
opinions of counsel in comparable transactions, to the effect that a public sale
or transfer of such Security may be made without registration under the
Securities Act; or (c) such holder provides the Company with reasonable
assurances that such Security can be sold under Rule 144. In the event the above
legend is removed from any Security and thereafter the effectiveness of a
registration statement covering such Security is suspended or the Company
determines that a supplement or amendment thereto


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is required by applicable securities laws, then upon reasonable advance written
notice to such Purchaser the Company may require that the above legend be placed
on any such Security that cannot then be sold pursuant to an effective
registration statement or under Rule 144 and such Purchaser shall cooperate in
the replacement of such legend. Such legend shall thereafter be removed when
such Security may again be sold pursuant to an effective registration statement
or under Rule 144.

        (h) Authorization; Enforcement. This Agreement and the Registration
Rights Agreements have been duly and validly authorized, executed and delivered
on behalf of such Purchaser and are valid and binding agreements of such
Purchaser enforceable against such Purchaser in accordance with their terms.

        (i) Residency. Such Purchaser is a resident of the jurisdiction set
forth under such Purchaser's name on the Execution Page hereto executed by such
Purchaser.

        (j) Prohibition on Short Sales. The Purchaser will not, prior to the
effectiveness of the Registration Statement filed in accordance with Section
2(a) of the First Registration Rights Agreement, if then prohibited by law or
regulation, engage in any short sale or have in effect a short position (whether
such short sale or position is against the box and regardless of when such
position was entered into).

        (k) Confidential Agreement. The Purchaser will hold in confidence all
information concerning this Agreement and the placement of shares hereunder
until the earlier of such time as (i) the Company has made a public announcement
concerning the Agreement and the placement of shares hereunder or (ii) this
Agreement is terminated.

        The Purchasers' representations and warranties made in this Article 2
are made solely for the purpose of permitting the Company to make a
determination that the offer and sale of the Preferred Shares and Warrants
pursuant to this Agreement complies with applicable U.S. federal and state
securities laws and not for any other purpose. Accordingly, the Company should
not rely on such representations and warranties for any other purpose.

3.      REPRESENTATIONS AND WARRANTIES OF THE COMPANY. Except as set forth on a
Schedule of Exceptions executed and delivered by the Company to the Purchasers
at Closing, the Company represents and warrants to each Purchaser as follows:

        (a) Organization and Qualification. The Company and each of its
subsidiaries is a corporation duly organized and existing in good standing under
the laws of the jurisdiction in which it is incorporated, and has the requisite
corporate power to own its properties and to carry on its business as now being
conducted. The Company and each of its subsidiaries is duly qualified as a
foreign corporation to do business and is in good standing in every jurisdiction
in



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which the nature of the business conducted by it makes such qualification
necessary and where the failure so to qualify would have a Material Adverse
Effect. "MATERIAL ADVERSE EFFECT" means any material adverse effect on (i) the
Securities, (ii) the ability of the Company to perform its obligations hereunder
or under the Certificate of Designation, the Warrants or the Registration Rights
Agreements or (iii) the business, operations, properties, prospects or financial
condition of the Company and its subsidiaries, taken as a whole.

        (b) Authorization; Enforcement. (i) The Company has the requisite
corporate power and authority to enter into and perform its obligations under
this Agreement, the Warrants and the Registration Rights Agreements, to issue
and sell the Units in accordance with the terms hereof, to issue the Conversion
Shares upon conversion of the Preferred Shares in accordance with the terms of
the Certificate of Designation and to issue the Warrant Shares upon exercise of
the Warrants in accordance with the terms of such Warrants; (ii) the execution,
delivery and performance of this Agreement, the Warrants and the Registration
Rights Agreements by the Company and the consummation by it of the transactions
contemplated hereby and thereby (including, without limitation, the issuance of
the Preferred Shares and Warrants and the issuance and reservation for issuance
of the Conversion Shares and Warrant Shares) have been duly authorized by the
Company's Board of Directors and no further consent or authorization of the
Company, its Board of Directors, or any committee of the Board of Directors is
required, and (iii) this Agreement constitutes, and, upon execution and delivery
by the Company of the Warrants and the Registration Rights Agreements, such
agreements will constitute, valid and binding obligations of the Company
enforceable against the Company in accordance with their terms.

        (c) Stockholder Authorization. Neither the execution, delivery or
performance by the Company of this Agreement, the Warrants or the Registration
Rights Agreements nor the consummation by it of the transactions contemplated
hereby or thereby (including, without limitation, the issuance of the Preferred
Shares or Warrants or the issuance or reservation for issuance of the Conversion
Shares or Warrant Shares) requires any consent or authorization of the Company's
stockholders, other than the consent required under Rule 4350(i) promulgated by
the NASD and any similar rule.

        (d) Capitalization. The capitalization of the Company as of the date
hereof, including the authorized capital stock, the number of shares issued and
outstanding, the number of shares issuable and reserved for issuance pursuant to
the Company's stock option plans, the number of shares issuable and reserved for
issuance pursuant to securities (other than the Preferred Shares and Warrants)
exercisable or exchangeable for, or convertible into, any shares of capital
stock and the number of shares to be reserved for issuance upon conversion of
the Preferred Shares and exercise of the Warrants is set forth on Schedule 3(d).
All of such outstanding shares of capital stock have been, or upon issuance in
accordance with the terms of any such warrants, options or preferred stock, will
be, validly issued, fully paid and non-assessable. No shares of capital stock


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of the Company (including the Preferred Shares, the Conversion Shares and the
Warrant Shares) are subject to preemptive rights or any other similar rights of
the stockholders of the Company or any liens or encumbrances. Except for the
Securities and as set forth on Schedule 3(d), as of the date of this Agreement,
(i) there are no outstanding options, warrants, scrip, rights to subscribe to,
calls or commitments of any character whatsoever relating to, or securities or
rights convertible into or exercisable or exchangeable for, any shares of
capital stock of the Company or any of its subsidiaries, or arrangements by
which the Company or any of its subsidiaries is or may become bound to issue
additional shares of capital stock of the Company or any of its subsidiaries,
nor are any such issuances or arrangements contemplated, and (ii) there are no
agreements or arrangements under which the Company or any of its subsidiaries is
obligated to register the sale of any of its or their securities under the
Securities Act (except the Registration Rights Agreements). Schedule 3(d) sets
forth all of the Company issued securities or instruments containing
antidilution or similar provisions that will be triggered by, and all of the
resulting adjustments that will be made to such securities and instruments as a
result of, the issuance of the Securities in accordance with the terms of this
Agreement, the Certificate of Designation or the Warrants. The Company has
furnished to the Purchasers true and correct copies of the Company's Certificate
of Incorporation as in effect on the date hereof ("CERTIFICATE OF
INCORPORATION"), the Company's By-laws as in effect on the date hereof (the
"BY-LAWS"), and all other instruments and agreements governing securities
convertible into or exercisable or exchangeable for capital stock of the
Company. The Certificate of Designation, in the form attached hereto, will be
duly filed prior to Closing with the Secretary of State of the State of Delaware
and, upon the issuance of the Preferred Shares in accordance with the terms
hereof, each Purchaser shall be entitled to the rights set forth therein.

        (e) Issuance of Shares. The Preferred Shares are duly authorized and,
upon issuance in accordance with the terms of this Agreement, will be validly
issued, fully paid and non-assessable, and free from all taxes, liens, claims
and encumbrances (other than restrictions on transfer contained in this
Agreement and in the Registration Rights Agreements) and will not be subject to
preemptive rights, rights of first refusal or other similar rights of
stockholders of the Company and will not impose personal liability on the
holders thereof. The Conversion Shares and Warrant Shares are duly authorized
and reserved for issuance, and, upon conversion of the Preferred Shares and
exercise of the Warrants in accordance with the terms thereof, will be validly
issued, fully paid and non-assessable, and free from all taxes, liens, claims
and encumbrances (other than restrictions on transfer contained in this
Agreement and in the Registration Rights Agreements) and will not be subject to
preemptive rights, rights of first refusal or other similar rights of
stockholders of the Company and will not impose personal liability upon the
holder thereof.

        (f) No Conflicts. The execution, delivery and performance of this
Agreement, the Warrants and the Registration Rights Agreements by the Company,
the performance by the Company of its obligations under the Certificate of
Designation, and the consummation by the


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Company of the transactions contemplated hereby and thereby (including, without
limitation, the issuance and reservation for issuance, as applicable, of the
Preferred Shares, Warrants, Conversion Shares and Warrant Shares) will not (i)
result in a violation of the Certificate of Incorporation or By-laws or (ii)
conflict with, or constitute a default (or an event that with notice or lapse of
time or both would become a default) under, or give to others any rights of
termination, amendment (including, without limitation, the triggering of any
anti-dilution provisions), acceleration or cancellation of, any agreement,
indenture or instrument to which the Company or any of its subsidiaries is a
party, or result in a violation of any law, rule, regulation, order, judgment or
decree (including United States federal and state securities laws and
regulations and rules or regulations of any self-regulatory organizations to
which either the Company or its securities are subject) applicable to the
Company or any of its subsidiaries or by which any property or asset of the
Company or any of its subsidiaries is bound or affected (except, with respect to
clause (ii), for such conflicts, defaults, terminations, amendments,
accelerations, cancellations and violations that would not, individually or in
the aggregate, have a Material Adverse Effect). Neither the Company nor any of
its subsidiaries is in violation of its Certificate of Incorporation, By-laws or
other organizational documents and neither the Company nor any of its
subsidiaries is in default (and no event has occurred which, with notice or
lapse of time or both, would put the Company or any of its subsidiaries in
default) under, nor has there occurred any event giving others (with notice or
lapse of time or both) any rights of termination, amendment, acceleration or
cancellation of, any agreement, indenture or instrument to which the Company or
any of its subsidiaries is a party, except for actual or possible violations,
defaults or rights that would not, individually or in the aggregate, have a
Material Adverse Effect. The businesses of the Company and its subsidiaries are
not being conducted, and shall not be conducted so long as a Purchaser owns any
of the Preferred Shares, in violation of any law, ordinance or regulation of any
governmental entity, except for possible violations the sanctions for which
either singly or in the aggregate would not have a Material Adverse Effect.
Except as specifically contemplated by this Agreement and the Registration
Rights Agreements, the Company is not required to obtain any consent, approval,
authorization or order of, or make any filing or registration with, any court or
governmental agency or any regulatory or self regulatory agency in order for it
to execute, deliver or perform any of its obligations under this Agreement, the
Warrants or the Registration Rights Agreements or to perform its obligations
under the Certificate of Designation, in each case in accordance with the terms
hereof or thereof. The Company is not in violation of the listing requirements
of the Nasdaq National Market ("NNM") and has received no notice regarding the
potential delisting of the Common Stock by the NNM.

        (g) SEC Documents, Financial Statements. Since December 31, 2000, the
Company has timely filed (within applicable extension periods) all reports,
schedules, forms, statements and other documents required to be filed by it with
the SEC pursuant to the reporting requirements of the Securities Exchange Act of
1934, as amended (the "EXCHANGE ACT") (all of the foregoing filed prior to the
date hereof and all exhibits included therein and financial


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statements and schedules thereto and documents incorporated by reference
therein, being hereinafter referred to herein as the "SEC DOCUMENTS"). The
Company has delivered to each Purchaser true and complete copies of the SEC
Documents. To the extent that any SEC Document is available under the SEC's
EDGAR filing system, such SEC Document shall be deemed to have been delivered to
each of the Purchasers. As of their respective dates, the SEC Documents complied
in all material respects with the requirements of the Exchange Act or the
Securities Act, as the case may be, and the rules and regulations of the SEC
promulgated thereunder applicable to the SEC Documents, and none of the SEC
Documents, at the time they were filed with the SEC, contained any untrue
statement of a material fact or omitted to state a material fact required to be
stated therein or necessary in order to make the statements therein, in light of
the circumstances under which they were made, not misleading. None of the
statements made in any such SEC Documents is, or has been, required to be
amended or updated under applicable law (except for such statements as have been
amended or updated in subsequent filings made prior to the date hereof). As of
their respective dates, the financial statements of the Company included in the
SEC Documents complied as to form in all material respects with applicable
accounting requirements and the published rules and regulations of the SEC
applicable with respect thereto. Such financial statements have been prepared in
accordance with U.S. generally accepted accounting principles ("GAAP"),
consistently applied, during the periods involved (except (i) as may be
otherwise indicated in such financial statements or the notes thereto, or (ii)
in the case of unaudited interim statements, to the extent they may not include
footnotes or may be condensed or summary statements) and fairly present in all
material respects the consolidated financial position of the Company and its
consolidated subsidiaries as of the dates thereof and the consolidated results
of their operations and cash flows for the periods then ended (subject, in the
case of unaudited statements, to immaterial year-end audit adjustments). Except
as set forth in the financial statements of the Company included in the SEC
Documents filed prior to the date hereof, the Company has no liabilities,
contingent or otherwise, other than (i) liabilities incurred in the ordinary
course of business subsequent to the date of such financial statements and (ii)
obligations under contracts and commitments incurred in the ordinary course of
business and not required under GAAP to be reflected in such financial
statements, which liabilities and obligations referred to in clauses (i) and
(ii), individually or in the aggregate, are not material to the financial
condition or operating results of the Company.

        (h) Absence of Certain Changes. Since December 31, 2000, there has been
no material adverse change and no material adverse development in the business,
properties, operations, prospects, financial condition or results of operations
of the Company and its subsidiaries, taken as a whole, except as disclosed in
the SEC Documents filed prior to the date hereof.

        (i) Absence of Litigation. Except as disclosed in the SEC Documents
filed prior to the date hereof, there is no action, suit, proceeding, inquiry or
investigation before or by any court, public board, government agency,
self-regulatory organization or body, including, without


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limitation, the SEC or NASDAQ, pending or, to the knowledge of the Company or
any of its subsidiaries, threatened against or affecting the Company, any of its
subsidiaries, or any of their respective directors or officers in their
capacities as such. There are no facts which, if known by a potential claimant
or governmental authority, could give rise to a claim or proceeding which, if
asserted or conducted with results unfavorable to the Company or any of its
subsidiaries, could reasonably be expected to have a Material Adverse Effect.

        (j) Intellectual Property. Each of the Company and its subsidiaries owns
or is licensed to use all patents, patent applications, trademarks, trademark
applications, trade names, service marks, copyrights, copyright applications,
licenses, permits, inventions, discoveries, processes, scientific, technical,
engineering and marketing data, object and source codes, know-how (including
trade secrets and other unpatented and/or unpatentable proprietary or
confidential information, systems or procedures) and other similar rights and
proprietary knowledge (collectively, "INTANGIBLES") necessary for the conduct of
its business as now being conducted. To the best knowledge of the Company,
neither the Company nor any subsidiary of the Company infringes or is in
conflict with any right of any other person with respect to any Intangibles.
Except as set forth on Schedule 3(j), neither the Company nor any of its
subsidiaries has received written notice of any pending conflict with or
infringement upon such third party Intangibles. The termination of the Company's
ownership of, or right to use, any single Intangible would not result in a
Material Adverse Effect on the Company. Neither the Company nor any of its
subsidiaries has entered into any consent agreement, indemnification agreement,
forbearance to sue or settlement agreement with respect to the validity of the
Company's or its subsidiaries' ownership or right to use its Intangibles and, to
the best knowledge of the Company, there is no reasonable basis for any such
claim to be successful. The Intangibles are valid and enforceable and no
registration relating thereto has lapsed, expired or been abandoned or canceled
or is the subject of cancellation or other adversarial proceedings, and all
applications therefor are pending and in good standing. The Company and its
subsidiaries have complied, in all material respects, with their respective
contractual obligations relating to the protection of the Intangibles used
pursuant to licenses. To the best knowledge of the Company, no person is
infringing on or violating the Intangibles owned or used by the Company or its
subsidiaries.

        (k) Foreign Corrupt Practices. Neither the Company, nor any of its
subsidiaries, nor any director, officer, agent, employee or other person acting
on behalf of the Company or any subsidiary has, in the course of his actions
for, or on behalf of, the Company, used any corporate funds for any unlawful
contribution, gift, entertainment or other unlawful expenses relating to
political activity; made any direct or indirect unlawful payment to any foreign
or domestic government official or employee from corporate funds; violated or is
in violation of any provision of the U.S. Foreign Corrupt Practices Act of 1977;
or made any bribe, rebate, payoff, influence payment, kickback or other unlawful
payment to any foreign or domestic government official or employee.


                                      -11-
<PAGE>   12


        (l) Disclosure. All information relating to or concerning the Company
set forth in this Agreement or provided to any Purchaser pursuant to Section
2(d) hereof or otherwise in connection with the transactions contemplated hereby
is true and correct in all material respects and the Company has not omitted to
state any material fact necessary in order to make the statements made herein or
therein, in light of the circumstances under which they were made, not
misleading.

        (m) Acknowledgment Regarding Purchasers' Purchase of the Units. The
Company acknowledges and agrees that none of the Purchasers is acting as a
financial advisor or fiduciary of the Company (or in any similar capacity) with
respect to this Agreement or the transactions contemplated hereby, the
relationship between the Company and the Purchasers is "arms-length" and any
statement made by any Purchaser or any of its representatives or agents in
connection with this Agreement and the transactions contemplated hereby is
merely incidental to such Purchaser's purchase of Securities and has not been
relied upon by the Company, its officers or directors in any way. The Company
further acknowledges that the Company's decision to enter into this Agreement
has been based solely on an independent evaluation by the Company and its
representatives.

        (n) Listing. The Company has secured the listing of the Conversion
Shares and Warrant Shares upon each national securities exchange or automated
quotation system upon which shares of Common Stock are currently listed (subject
to official notice of issuance).

        (o) Form S-3 Eligibility. The Company is currently eligible to register
the resale of its Common Stock on a registration statement on Form S-3 under the
Securities Act. There exist no facts or circumstances that would prohibit or
delay the preparation and filing of a registration statement on Form S-3 with
respect to the Registrable Securities (as defined in the Registration Rights
Agreements). The Company has no basis to believe that its past or present
independent public auditors will withhold their consent to the inclusion, or
incorporation by reference, of their audit opinion concerning the Company's
financial statements which are included in the Registration Statement required
to be filed pursuant to the Registration Rights Agreements.

        (p) No General Solicitation. Neither the Company nor any distributor
participating on the Company's behalf in the transactions contemplated hereby
(if any) nor any person acting for the Company, or any such distributor, has
conducted any "general solicitation," as such term is defined in Regulation D,
with respect to any of the Securities being offered hereby.

        (q) No Integrated Offering. Neither the Company, nor any of its
affiliates, nor any person acting on its or their behalf, has directly or
indirectly made any offers or sales of any security or solicited any offers to
buy any security under circumstances that would require registration of the
Securities being offered hereby under the Securities Act or cause this offering
of Securities to be integrated with any prior offering of securities of the
Company for purposes of


                                      -12-
<PAGE>   13


the Securities Act or any applicable stockholder approval provisions, including,
without limitation, Rule 4350(i) of the NASD or any similar rule.

        (r) No Brokers. The Company has taken no action which would give rise to
any claim by any person for brokerage commissions, finder's fees or similar
payments by any Purchaser relating to this Agreement or the transactions
contemplated hereby.

        (s) Acknowledgment Regarding Securities. The number of Conversion Shares
issuable upon conversion of the Preferred Shares may increase in certain
circumstances, including if the price of the Common Stock declines. The
Company's executive officers have studied and fully understand the nature of the
Securities being sold hereunder. The Company acknowledges that its obligation to
issue Conversion Shares upon conversion of the Preferred Shares in accordance
with the Certificate of Designation is, other than as set forth in the
Certificate of Designation, absolute and unconditional, regardless of the
dilution that such issuance may have on the ownership interests of other
stockholders and the availability of remedies provided for in the Transaction
Documents relating to a failure or refusal to issue Conversion Shares. Taking
the foregoing into account, the Company's Board of Directors has determined in
its good faith business judgment that the issuance of the Preferred Shares and
Warrants hereunder and the consummation of the other transactions contemplated
hereby are in the best interests of the Company and its stockholders. The
Company's Board of Directors and executive officers fully intend to honor their
obligations hereunder to issue Conversion Shares upon conversion of the
Preferred Shares regardless of the dilution that such issuance may have on the
ownership interests of other stockholders and the availability of remedies
provided for in the Transaction Documents relating to their failure or refusal
to issue Conversion Shares.

        (t) Title. The Company and its subsidiaries have good and marketable
title in fee simple to all real property and good and merchantable title to all
personal property owned by them that is material to the business of the Company
and its subsidiaries, in each case free and clear of all liens, encumbrances and
defects except such as do not materially affect the value of such property and
do not materially interfere with the use made and proposed to be made of such
property by the Company and its subsidiaries. Any real property and facilities
held under lease by the Company and its subsidiaries are held by them under
valid, subsisting and enforceable leases with such exceptions as are not
material and do not materially interfere with the use made and proposed to be
made of such property and buildings by the Company and its subsidiaries.

        (u) Tax Status. Except as set forth in the SEC Documents, the Company
and each of its subsidiaries has made or filed all foreign, U.S. federal, state
and local income and all other tax returns, reports and declarations required by
any jurisdiction to which it is subject (unless and only to the extent that the
Company and each of its subsidiaries has set aside on its books provisions
reasonably adequate for the payment of all unpaid and unreported taxes) and has
paid all taxes and other governmental assessments and charges that are material
in amount, shown or


                                      -13-
<PAGE>   14

determined to be due on such returns, reports and declarations, except those
being contested in good faith and has set aside on its books provisions
reasonably adequate for the payment of all taxes for periods subsequent to the
periods to which such returns, reports or declarations apply. There are no
unpaid taxes in any material amount claimed to be due by the taxing authority of
any jurisdiction, and the officers of the Company know of no basis for any such
claim. The Company has not executed a waiver with respect to any statute of
limitations relating to the assessment or collection of any federal, state or
local tax. None of the Company's tax returns is presently being audited by any
taxing authority.

        (v) Key Employees. Each of the Company's directors, officers and any Key
Employee (as defined below) is currently serving the Company in the capacity
disclosed in the SEC Documents. No Key Employee, to the best of the knowledge of
the Company and its subsidiaries, is, or is now expected to be, in violation of
any material term of any employment contract, confidentiality, disclosure or
proprietary information agreement, non-competition agreement, or any other
contract or agreement or any restrictive covenant, and the continued employment
of each Key Employee does not subject the Company or any of its subsidiaries to
any liability with respect to any of the foregoing matters. No Key Employee has,
to the knowledge of the Company and its subsidiaries, any intention to terminate
or limit his employment with, or services to, the Company or any of its
subsidiaries, nor, to the knowledge of the Company, is any such Key Employee
subject to any constraints which would cause such employee to be unable to
devote his full time and attention to such employment or services. "KEY
EMPLOYEE" means the persons listed on Schedule 3(v) and any individual who
assumes or performs any of the duties of a Key Employee.

        (w) Insurance. The Company has in force fire, casualty, product
liability and other insurance policies, with extended coverage and in such
amounts as are customarily carried by persons engaged in the same or similar
business as the Company. No default or event has occurred that could give rise
to a default under any such policy.

        (x) Environmental Matters. There is no environmental litigation or other
environmental proceeding pending or threatened by any governmental regulatory
authority or others with respect to the current or any former business of the
Company or any partnership or joint venture currently or at any time affiliated
with the Company. No state of facts exists as to environmental matters or
Hazardous Substances (as defined below) that involves the reasonable likelihood
of a material capital expenditure by the Company or that may otherwise have a
Material Adverse Effect. No Hazardous Substances have been treated, stored or
disposed of, or otherwise deposited, in or on the properties owned or leased by
the Company or by any partnership or joint venture currently or at any time
affiliated with the Company in violation of any applicable environmental laws.
The environmental compliance programs of the Company comply in all respects with
all environmental laws, whether federal, state or local, currently in effect. As
used herein, "HAZARDOUS SUBSTANCES" means any substance, waste, contaminant,


                                      -14-
<PAGE>   15

pollutant or material that has been determined by any governmental authority to
be capable of posing a risk of injury to health, safety, property or the
environment.

        (y) Inventory. All inventory of the Company and its subsidiaries is
valued on the Company's consolidated books and records at the lower of standard
cost, which approximates actual cost, or the fair market value thereof. Except,
to the extent of the Company's reserves for obsolete or unmerchantable inventory
reflected in the Company's SEC Documents, all such inventory, after
consideration of reserves consisting of finished goods is of merchantable
quality and is saleable in the ordinary course of business consistent with past
practice.

        (z) Regulatory Permits. The Company possesses all certificates,
authorizations and permits issued by the appropriate federal, state or foreign
regulatory authorities which are material to conduct its business, and the
Company has not received any written notice of any proceeding relating to the
revocation or modification of any such certificate, authorization or permit.

4.      COVENANTS.

        (a) Best Efforts. The parties shall use their best efforts timely to
satisfy each of the conditions described in Section 6 and Section 7 of this
Agreement.

        (b) Form D: Blue Sky Laws. The Company shall file with the SEC a Form D
with respect to the Securities as required under Regulation D and provide a copy
thereof to each Purchaser promptly after such filing. The Company shall, on or
before the Closing Date, take such action as the Company shall reasonably
determine is necessary to qualify the Securities for sale to each Purchaser
pursuant to this Agreement under applicable securities or "blue sky" laws of the
states of the United States or obtain exemption therefrom, and shall provide
evidence of any such action so taken to each Purchaser on or prior to the
Closing Date. Within four (4) trading days after the Closing Date, the Company
shall file a Form 8-K concerning this Agreement and the transactions
contemplated hereby, which Form 8-K shall attach this Agreement and its Exhibits
as exhibits to such Form 8-K.

        (c) Reporting Status. So long as any Purchaser beneficially owns any of
the Securities, the Company shall timely file (within applicable extension
periods) all reports required to be filed with the SEC pursuant to the Exchange
Act, and the Company shall not terminate its status as an issuer required to
file reports under the Exchange Act even if the Exchange Act or the rules and
regulations thereunder would permit such termination. In addition, the Company
shall take all actions reasonably necessary to meet the "registrant eligibility"
requirements set forth in the general instructions to Form S-3 or any successor
form thereto, to continue to be eligible to register the resale of its Common
Stock on a registration statement on Form S-3 under the Securities Act.


                                      -15-
<PAGE>   16

        (d) Use of Proceeds. The Company shall use the proceeds from the sale of
the Preferred Shares and Warrants for general corporate purposes and working
capital and such proceeds shall not be used to repay indebtedness (other than
indebtedness incurred in the ordinary course of business), make acquisitions, or
make payments to stockholders or affiliates of the Company. Subject to the use
of proceeds as outlined above, the Company will invest the proceeds (i) in
evidences of indebtedness issued or fully guaranteed by the United States of
America and having a maturity of not more than one year from the date of
acquisition; (ii) in certificates of deposit, notes, acceptances and repurchase
agreements having a maturity of not more than one year from the date of
acquisition issued by a bank organized in the United States having capital,
surplus and undivided profits of at least $500,000,000; (iii) in the
highest-rated commercial paper having a maturity of not more than one year from
the date of acquisition; and (iv) in "Money Market" fund shares, or in money
market accounts fully insured by the Federal Deposit Insurance Corporation and
sponsored by banks and other financial institutions, provided that the
investments consist principally of the types of investments described in clauses
(i), (ii), or (iii) above.

        (e) Participation Right. Subject to the terms and conditions specified
in this Section 4(e), for a period of one year after the date that the
Registration Statement (as defined in the Registration Rights Agreement) the
Company is required to file pursuant to Section 2(a) of the Second Registration
Rights Agreement is declared effective, the Purchasers shall have a right to
participate with respect to the issuance or possible issuance of (i) future
equity or equity-linked securities, or (ii) debt which is convertible into
equity or in which there is an equity component ("ADDITIONAL SECURITIES") on the
same terms and conditions as offered by the Company to the other purchasers of
such Additional Securities. Each time the Company proposes to offer any
Additional Securities, the Company shall make an offering of such Additional
Securities to each Purchaser in accordance with the following provisions:

           (i) the Company shall deliver a notice (the "NOTICE") to the
Purchasers stating (i) its bona fide intention to offer such Additional
Securities, (ii) the number of such Additional Securities to be offered, (iii)
the price and terms, if any, upon which it proposes to offer such Additional
Securities, and (iv) the anticipated closing date of the sale of such Additional
Securities.

           (ii) by written notification received by the Company, within twenty
(20) days after giving of the Notice, any Purchaser may elect to purchase or
obtain, at the price and on the terms specified in the Notice, up to that
portion of such Additional Securities which equals the proportion that the
number of shares of Common Stock purchased by such Purchaser pursuant to the
terms hereof bears to the total number of shares of Common Stock then
outstanding (assuming in each case full conversion and exercise of all
convertible or exercisable securities then outstanding). The Company shall
promptly, in writing, inform each Purchaser which elects to purchase all of the
Additional Shares available to it ("FULLY-EXERCISING PURCHASER") of any



                                      -16-
<PAGE>   17

other Purchaser's failure to do likewise. During the five-day period commencing
after such information is given, each Fully-Exercising Purchaser shall be
entitled to obtain that portion of the Additional Securities for which the
Purchasers were entitled to subscribe but which were not subscribed for by the
Purchasers which is equal to the proportion that the number of shares of Common
Stock held by such Fully-Exercising Purchaser bears to the total number of
shares of Common Stock held by all Fully-Exercising Purchasers who wish to
purchase some of the unsubscribed shares;

           (iii) if all Additional Securities which the Purchasers are entitled
to obtain pursuant to subsection 4(e)(ii) are not elected to be obtained as
provided in subsection 4(e)(ii) hereof, the Company may, during the 75-day
period following the expiration of the period provided in subsection 4(e)(ii)
hereof, offer the remaining unsubscribed portion of such Additional Securities
to any person or persons at a price not less than, and upon terms no more
favorable to the offeree than, those specified in the Notice. If the Company
does not consummate the sale of such Additional Securities within such period,
the right provided hereunder shall be deemed to be revived and such Additional
Securities shall not be offered or sold unless first reoffered to the Purchasers
in accordance herewith;

           (iv) the participation right in this Section 4(e) shall not be
applicable to (i) the issuance or sale of shares of Common Stock (or options
therefor) to employees, officers, directors, or consultants of the Company for
the primary purpose of soliciting or retaining their employment or service
pursuant to a stock option plan (or similar equity incentive plan) approved by
the Board of Directors, (ii) the issuance of securities in connection with a
bona fide underwritten public offering at an offering price per share (prior to
underwriter's commissions and discounts) of not less than $5.10 per share (as
adjusted to reflect any stock dividends, distributions, combinations,
reclassifications and other similar transactions effected by the Corporation in
respect to its Common Stock) that results in total proceeds to the Company of at
least $40,000,000, (iii) the issuance or sale of the Preferred Shares, (iv) the
issuance of securities in connection with mergers, acquisitions, strategic
business partnerships or joint ventures (including, without limitation, such
transactions with major pharmaceutical labs or life sciences companies), the
primary purpose of which, in the reasonable judgment of the Board of Directors,
is not to raise additional capital, (v) the issuance of securities pursuant to
any equipment financing from a bank or similar financial or lending institution
approved by the Board of Directors, or (vi) any issuance of securities as to
which the holders of a majority of the then outstanding Preferred Shares shall
have executed a written waiver of the rights contained in this Section 4(e).

           (v) the participation right set forth in this Section 4(e) may not be
assigned or transferred, except that such right is assignable by each Purchaser
to any wholly-owned subsidiary or parent of, or to any corporation or entity
that is, within the meaning of the Securities Act, controlling, controlled by or
under common control with, any such Purchaser.



                                      -17-
<PAGE>   18

        (f) Expenses. The Company shall pay to SDS Capital Partners ("SDS
CAPITAL") at the Closing, reimbursement for the out-of-pocket expenses
reasonably incurred by SDS Capital's advisors in connection with the
negotiation, preparation, execution and delivery of this Agreement and the other
agreements to be executed in connection herewith, including, without limitation,
SDS Capital's advisors' reasonable due diligence and attorneys' fees and
expenses (the "EXPENSES"); provided, however, that in lieu of such payment SDS
Capital (or its affiliates) shall be permitted to deduct all Expenses from the
purchase price payable by SDS Capital (or its affiliates) hereunder. In
addition, from time to time thereafter, upon SDS Capital's written request, the
Company shall pay to SDS Capital such additional Expenses, if any, not covered
by such payment, in each case to the extent reasonably incurred by SDS Capital's
agents prior to the Closing in connection with the negotiation, preparation,
execution and delivery of this Agreement.

        (g) Financial Information. The Company shall send the following reports
to each Purchaser until such Purchaser transfers, assigns or sells all of its
Securities: within ten (10) days after the filing with the SEC, a copy of its
Annual Report on Form 10-K, its Quarterly Reports on Form 10-Q, its proxy
statements and any Current Reports on Form 8-K. To the extent that any of the
foregoing documents is available under the SEC's EDGAR filing system, such
documents shall be deemed to have been delivered to each of the Purchasers.

        (h) Reservation of Shares. The Company shall at all times have
authorized and reserved for the purpose of issuance a sufficient number of
shares of Common Stock to provide for the full conversion of the outstanding
Preferred Shares (and all Premiums (as defined in the Certificate of
Designation) thereon) and issuance of the Conversion Shares in connection
therewith, the full exercise of the Warrants and the issuance of the Warrant
Shares in connection therewith and in each case to the extent required by the
Certificate of Designation and the Warrants.

        (i) Listing. The Company shall have filed an application for the listing
of the Conversion Shares and the Warrant Shares on the NNM on or before the
First Closing. From the time that such application has been approved and
thereafter, the Company shall maintain, so long as any Purchaser (or any of
their affiliates) own any Securities, the listing of all Conversion Shares and
Warrant Shares from time to time issuable upon conversion of the Preferred
Shares and exercise of the Warrants on each national securities exchange or
automated quotation system on which shares of Common Stock are currently listed.
The Company will use its best efforts to continue the listing and trading of its
Common Stock on the NNM, the New York Stock Exchange ("NYSE"), the American
Stock Exchange ("AMEX") or the Nasdaq SmallCap Market (the "SMALLCAP") and will
comply in all material respects with the reporting, filing and other obligations
under the bylaws or rules of the NASD and such exchanges, as applicable. The
Company shall promptly provide to each holder of Preferred Shares and/or
Warrants copies of any notices it receives regarding the continued eligibility
of the Common Stock for trading on


                                      -18-
<PAGE>   19

the NNM or, if applicable, any securities exchange or automated quotation system
on which securities of the same class or series issued by the Company are then
listed or quoted, if any.

        (j) Corporate Existence. So long as a Purchaser beneficially owns any
Securities, the Company shall maintain its corporate existence, and in the event
of a merger, consolidation or sale of all or substantially all of the Company's
assets, the Company shall ensure that the surviving or successor entity in such
transaction (i) assumes the Company's obligations hereunder and under the
Certificate of Designation, the Warrants and the agreements and instruments
entered into in connection herewith regardless of whether or not the Company
would have had a sufficient number of shares of Common Stock authorized and
available for issuance in order to effect the conversion of all Preferred Shares
and exercise in full of all Warrants outstanding as of the date of such
transaction and (ii) is a publicly traded corporation whose common stock is
listed for trading on the NNM, SmallCap, NYSE or AMEX. Notwithstanding the
foregoing, the Company covenants and agrees that it will not engage in any
merger, consolidation or sale of all or substantially all of its assets at any
time prior to the effectiveness of the Registration Statement required to be
filed pursuant to the Second Registration Rights Agreement without (A) providing
each Purchaser with written notice of such transaction at least 60 days prior to
the consummation of such transaction and (B) obtaining the written consent of
the Purchasers holding a majority-in-interest of the then outstanding shares of
Series A Preferred Stock on or before the 10th day after the delivery of such
notice by the Company.

        (k) No Integrated Offerings. The Company shall not make any offers or
sales of any security (other than the Securities) under circumstances that would
require registration of the Securities being offered or sold hereunder under the
Securities Act or cause this offering of the Securities to be integrated with
any other offering of securities by the Company for purposes of any stockholder
approval provision applicable to the Company or its securities.

        (l) Legal Compliance. The Company shall conduct its business and the
business of its subsidiaries in compliance with all laws, ordinances or
regulations of governmental entities applicable to such businesses, except where
the failure to do so would not have a Material Adverse Effect.

        (m) Redemptions and Dividends. So long as any Purchaser beneficially
owns any Preferred Shares, the Company shall not, without first obtaining the
written approval of such Purchaser, repurchase, redeem, or declare or pay any
cash dividend or distribution on, any shares of capital stock of the Company.

        (n) Information. The Company will furnish to each Purchaser, so long as
it holds any Preferred Shares:


                                      -19-
<PAGE>   20

           (i) concurrently with the filing with the SEC of its annual reports
on Form 10-K, a certificate of the President, a Vice President or a senior
financial officer of the Company stating that, based upon such examination or
investigation and review of this Agreement as in the opinion of the signer is
necessary to enable the signer to express an informed opinion with respect
thereto, neither the Company nor any of its subsidiaries is or has during such
period been in default in the performance or observance of any of the terms,
covenants or conditions hereof, or, if the Company or any of its subsidiaries
shall be or shall have been in default, specifying all such defaults, and the
nature and period of existence thereof, and what action the Company or such
subsidiary has taken, is taking or proposes to take with respect thereto; and

           (ii) the information the Company must deliver to any holder or to any
prospective transferee of Securities in order to permit the sale or other
transfer of such Securities pursuant to Rule 144A of the SEC or any similar rule
then in effect.

           The Company will keep at its principal executive office a true copy
of this Agreement (as at the time in effect), and cause the same to be available
for inspection at such office during normal business hours by any holder of
Securities or any prospective transferee of Securities designated by a holder
thereof.

        (o) Inspection of Properties and Books. So long as any Purchaser shall
hold any Securities, such Purchaser and its representatives and agents
(collectively, the "INSPECTORS") shall have the right, at such Purchaser's
expense, to visit and inspect any of the properties of the Company and of its
subsidiaries, to examine the books of account and records of the Company and of
its subsidiaries, to make or be provided with copies and extracts therefrom, to
discuss the affairs, finances and accounts of the Company and of its
subsidiaries with, and to be advised as to the same by, its and their officers,
employees and independent public accountants (and by this provision the Company
authorizes such accountants to discuss such affairs, finances and accounts,
whether or not a representative of the Company is present) all at such
reasonable times and intervals and to such reasonable extent as such Purchaser
may desire; provided, however, that each Inspector shall hold in confidence and
shall not make any disclosure (except to such Purchaser) of any such information
which the Company determines in good faith to be confidential, and of which
determination the Inspectors are so notified, unless (a) the disclosure of such
information is necessary to avoid or correct a misstatement or omission in any
Registration Statement filed pursuant to the Registration Rights Agreements, (b)
the release of such information is ordered pursuant to a subpoena or other order
from a court or government body of competent jurisdiction, or (c) such
information has been made generally available to the public other than by
disclosure in violation of this or any other agreement. The Company shall not be
required to disclose any confidential information to any Inspector until and
unless such Inspector shall have entered into confidentiality agreements (in
form and substance satisfactory to the company) with the Company with respect
thereto, substantially in the form of this Section 4(o). Each Purchaser agrees
that it shall, upon learning that disclosure of such information is


                                      -20-
<PAGE>   21

sought in or by a court or governmental body of competent jurisdiction or
through other means, give prompt notice to the Company and allow the Company, at
its expense, to undertake appropriate action to prevent disclosure of, or to
obtain a protective order for, the information deemed confidential.
Notwithstanding the foregoing, the Company shall be permitted to withhold from
disclosure under this paragraph any material protected by attorney-client
privilege.

        (p) Stockholder Approval. The Company shall call a meeting of its
stockholders to be held as promptly as practicable and in any event no later
than 90 days after the date hereof for the purpose of voting upon and approving
the authorization and issuance of the Preferred Shares and the Warrants, and the
issuance of the Conversion Shares upon conversion of the Preferred Shares or
otherwise pursuant to the Certificate of Designation and the Warrant Shares upon
exercise of or otherwise pursuant to the Warrants (the "STOCKHOLDER APPROVAL").
The Company shall recommend to its stockholders approval of such matters. The
Company shall use its reasonable best efforts to solicit from its stockholders
proxies in favor of such matters sufficient to comply with all relevant legal
requirements, including, without limitation, Rule 4350(i) promulgated by the
NASD, and shall vote such proxies and, shall use its best efforts to cause all
"affiliates" (as such term is defined in Rule 12b-2 promulgated under the
Exchange Act) of the Company to vote any shares of Common Stock beneficially
owned by such persons or entities, in favor of such matters.

        (q) Trading Restrictions. No Purchaser shall be permitted to sell,
transfer or otherwise dispose of, during any 45 trading day period, more than
4.99% of the least number of shares of Common Stock issued and outstanding
during such 45 trading day period (other than dispositions to the Company). The
restriction contained in this Section 4(q) may not be altered, amended, deleted
or changed in any manner whatsoever unless the holders of a majority of the
outstanding shares of Common Stock and the holders of the Preferred Shares and
Warrants shall approve, in writing, such alteration, amendment, deletion or
change.

        (r) Filing of Registration Rights. The parties have agreed that, for
administrative ease, the Company shall file two registration statements covering
the Conversion Shares and Warrant Shares underlying the Units to be sold in the
First Closing and the Second Closing, as described in the Registration Rights
Agreements. However, in the event the parties determine by mutual consent (which
shall not be unreasonably withheld) to consolidate such registrations, the
parties shall enter into an amendment to the Registration Rights Agreements to
such effect.

        (s) Waivers and Consents. Prior to the effectiveness any Registration
Statement filed in accordance with Section 2(a) of the First Registration Rights
Agreement or the Second Registration Rights Agreement, the Company shall have
obtained proper waivers from the stockholders and warrant holders referred to on
Schedule 3(f) of the Schedule of Exceptions to this Agreement.


                                      -21-
<PAGE>   22

5.      TRANSFER AGENT INSTRUCTIONS.

        (a) The Company shall instruct its transfer agent to issue certificates
(subject to the legend and other provisions hereof and in the Certificate of
Designation and the Warrants), registered in the name of each Purchaser or its
nominee, for the Conversion Shares and the Warrant Shares in such amounts as
specified from time to time by such Purchaser to the Company upon conversion of
the Preferred Shares or exercise of the Warrants, as applicable. To the extent
and during the periods provided in Sections 2(f) and 2(g) of this Agreement, all
such certificates shall bear the restrictive legend specified in Section 2(g) of
this Agreement.

        (b) The Company warrants that no instruction other than such
instructions referred to in this Section 5, the Registration Rights Agreement
and stop transfer instructions to give effect to Section 2(f) hereof in the case
of the transfer of the Conversion Shares or Warrant Shares prior to registration
of the Conversion Shares and Warrant Shares under the Securities Act or without
an exemption therefrom, will be given by the Company to its transfer agent and
that the Securities shall otherwise be freely transferable on the books and
records of the Company as and to the extent provided in this Agreement and the
Registration Rights Agreements. Nothing in this Section shall affect in any way
each Purchaser's obligations and agreement set forth in Section 2(g) hereof to
resell the Securities pursuant to an effective registration statement or under
an exemption from the registration requirements of applicable securities law.

        (c) If any Purchaser provides the Company and the transfer agent with an
opinion of counsel, which opinion of counsel shall be in form, substance and
scope customary for opinions of counsel in comparable transactions, to the
effect that the Securities have been sold or transferred pursuant to an
exemption from registration, or any Purchaser provides the Company with an
opinion of counsel, which opinion of counsel shall be in form, substance and
scope customary for opinions of counsel in comparable transactions, to the
effect that such Securities may be sold under Rule 144(k), the Company shall
permit the transfer and, in the case of the Conversion Shares and Warrant
Shares, promptly instruct its transfer agent to issue one or more certificates
in such name and in such denominations as specified by such Purchaser.

6.      CONDITIONS TO THE COMPANY'S OBLIGATION TO SELL.

        The obligation of the Company hereunder to issue and sell the Units to
each Purchaser hereunder is subject to the satisfaction, at or before the First
Closing and the Second Closing, as applicable, of each of the following
conditions thereto, provided that these conditions are for the Company's sole
benefit and may be waived by the Company at any time in its sole discretion.

        (a) with respect to the First Closing and the Second Closing:



                                      -22-
<PAGE>   23

            (i) Each Purchaser shall have executed such Purchaser's Execution
Page to this Agreement and the Registration Rights Agreements and delivered the
same to the Company.

            (ii) Each Purchaser shall have delivered such Purchaser's Purchase
Price for the Units being purchased at such Closing in accordance with Section
1(b) above.

            (iii) The representations and warranties of each Purchaser shall be
true and correct as of the date when made and as of the First Closing Date and
the Second Closing Date, as applicable, as though made at that time (except for
representations and warranties that speak as of a specific date, which
representations and warranties shall be true and correct as of such date), and
such Purchaser shall have performed, satisfied and complied in all material
respects with the covenants, agreements and conditions required by this
Agreement to be performed, satisfied or complied with by such Purchaser at or
prior to the First Closing Date or Second Closing Date, as applicable.

            (iv) No statute, rule, regulation, executive order, decree, ruling
or injunction shall have been enacted, entered, promulgated or endorsed by any
court or governmental authority of competent jurisdiction or any self-regulatory
organization having authority over the matters contemplated hereby which
prohibits the consummation of any of the transactions contemplated by this
Agreement.

            (v) Prior to the effectiveness of the Registration Statement filed
in accordance with Section 2(a) of the First Registration Rights Agreement, the
Company shall have received from each Purchaser a fully completed Selling
Stockholder Questionnaire in a reasonable and customary form delivered to the
Purchaser by the Company prior to the Closing for the Company's use in preparing
the Registration Statement (as defined in the Registration Rights Agreements).

        (b) With respect to the Second Closing:

            (i) The Company shall have obtained the Stockholder Approval.

7.      CONDITIONS TO EACH PURCHASER'S OBLIGATION TO PURCHASE. The obligation of
each Purchaser hereunder to purchase the Units to be purchased by it at the
First Closing and Second Closing, as applicable, is subject to the satisfaction,
at or before the First Closing Date and the Second Closing Date, as applicable,
of each of the following conditions, provided that such conditions are for such
Purchaser's sole benefit and may be waived by such Purchaser at any time in such
Purchaser's sole discretion:

        (a) With respect to the First Closing:



                                      -23-
<PAGE>   24

            (i) The Company shall have executed this Agreement, the Warrants and
the Registration Rights Agreements, and delivered executed original copies of
the same to such Purchaser.

            (ii) The Certificate of Designation shall have been filed and
accepted for filing with the Secretary of State of the State of Delaware and a
copy thereof certified by the Secretary of State of Delaware shall have been
delivered to such Purchaser.

            (iii) The Company shall have delivered to such Purchaser duly
executed certificates and Warrant agreements (each in such denominations as such
Purchaser shall request) representing the Preferred Shares and Warrants being so
purchased by such Purchaser at the First Closing in accordance with Section 1(b)
above.

            (iv) The Common Stock shall be authorized for quotation and listed
on the NNM and trading in the Common Stock (or the NNM generally) shall not have
been suspended by the SEC or the NNM.

            (v) The representations and warranties of the Company shall be true
and correct as of the date when made and as of the First Closing Date as though
made at that time (except for representations and warranties that speak as of a
specific date, which representations and warranties shall be true and correct as
of such date) and the Company shall have performed, satisfied and complied in
all material respects with the covenants, agreements and conditions required by
this Agreement to be performed, satisfied or complied with by the Company at or
prior to the First Closing Date. The Company shall have delivered for the
benefit of the Purchasers, a certificate, executed by the Chief Executive
Officer of the Company after reasonable investigation, dated as of the First
Closing Date to the foregoing effect and as to such other matters as may
reasonably be requested by such Purchaser.

            (vi) No statute, rule, regulation, executive order, decree, ruling,
injunction, action or proceeding shall have been enacted, entered, promulgated
or endorsed by any court or governmental authority of competent jurisdiction or
any self-regulatory organization having authority over the matters contemplated
hereby which questions the validity of, challenges or prohibits the consummation
of, any of the transactions contemplated by this Agreement.

            (vii) Each Purchaser shall have received an opinion of the Company's
counsel, dated as of the First Closing Date, in form, scope and substance
reasonably satisfactory to the Purchaser and in substantially the form of
Exhibit D attached hereto.

            (viii) There shall have been no material adverse changes and no
material adverse developments in the business, properties, operations,
prospects, financial condition or results of operations of the Company and its
subsidiaries, taken as a whole, since the date hereof,


                                      -24-
<PAGE>   25

and no information, of which the Purchaser is not currently aware, shall come to
the attention of the Purchaser that is materially adverse to the Company.

           (ix) Each Purchaser shall have received a copy of resolutions, duly
adopted by the Board of Directors of the Company, which shall be in full force
and effect at the time of the Closing, authorizing the consummation by the
Company of the transactions contemplated hereby and by the Registration Rights
Agreements and the Warrant, certified as such by the Secretary or Assistant
Secretary of the Company.

           (x) The aggregate number of Units being purchased hereunder by all
Purchasers at the First Closing shall be 665.

        (b) With respect to the Second Closing :

            (i) The First Closing shall have occurred.

            (ii) The Company shall have delivered to such Purchaser duly
executed certificates and Warrant agreements (each in such denominations as such
Purchaser shall request) representing the Preferred Shares and Warrants being so
purchased by such Purchaser at the Second Closing in accordance with Section
1(b) above.

            (iii) The Common Stock shall be authorized for quotation and listed
on the NNM and trading in the Common Stock (or the NNM generally) shall not have
been suspended by the SEC or the NNM.

            (iv) The representations and warranties of the Company shall be true
and correct as of the date when made and as of the Second Closing Date as though
made at that time (except for representations and warranties that speak as of a
specific date, which representations and warranties shall be true and correct as
of such date) and the Company shall have performed, satisfied and complied in
all material respects with the covenants, agreements and conditions required by
this Agreement to be performed, satisfied or complied with by the Company at or
prior to the Second Closing Date. The Company shall have delivered for the
benefit of each Purchaser a certificate, executed by the Chief Executive Officer
of the Company after reasonable investigation, dated as of the Second Closing
Date to the foregoing effect and as to such other matters as may reasonably be
requested by such Purchaser.

            (v) No statute, rule, regulation, executive order, decree, ruling,
injunction, action or proceeding shall have been enacted, entered, promulgated
or endorsed by any court or governmental authority of competent jurisdiction or
any self-regulatory organization having authority over the matters contemplated
hereby which questions the validity of, challenges or prohibits the consummation
of, any of the transactions contemplated by this Agreement.


                                      -25-
<PAGE>   26

            (vi) Each Purchaser shall have received an opinion of the Company's
counsel, dated as of the Second Closing Date, in form, scope and substance
reasonably satisfactory to the Purchaser and in substantially the form of
Exhibit D attached hereto.

            (vii) There shall have been no material adverse changes and no
material adverse developments in the business, properties, operations,
prospects, financial condition or results of operations of the Company and its
subsidiaries, taken as a whole, since the date hereof, and no information, of
which the Purchaser is not currently aware, shall come to the attention of the
Purchaser that is materially adverse to the Company.

            (viii) The Registration Statement required to be filed by the
Company pursuant to Section 2(a) of the First Registration Rights Agreement
shall have been filed by the Filing Date (as defined in the First Registration
Rights Agreement) and declared effective by the SEC no later than 120 days after
the First Closing Date and shall be effective and available for use by the
Purchasers (i.e., as to the securities registered pursuant thereto) as of the
Second Closing Date.

            (ix) The Company shall not be in material default of any of its
obligations under this Agreement, the First Registration Rights Agreement or any
other agreement with the Purchasers.

            (x) The Company shall have obtained the Stockholder Approval.

            (xi) The Company shall have executed the Registration Rights
Agreements, and delivered executed original copies of the same to such
Purchaser.

8.      GOVERNING LAW; MISCELLANEOUS.

        (a) Governing Law; Jurisdiction. This Agreement shall be governed by and
construed in accordance with the laws of the State of Delaware applicable to
contracts made and to be performed in the State of Delaware. The Company and the
Purchasers irrevocably consent to the jurisdiction of the United States federal
courts and the state courts located in the State of Delaware in any suit or
proceeding based on or arising under this Agreement and irrevocably agree that
all claims in respect of such suit or proceeding may be determined in such
courts. The Company irrevocably waives the defense of an inconvenient forum to
the maintenance of such suit or proceeding. The Company further agrees that
service of process upon the Company mailed by first class mail shall be deemed
in every respect effective service of process upon the Company in any such suit
or proceeding. Nothing herein shall affect the right of any Purchaser to serve
process in any other manner permitted by law. The Company agrees that a final
non-appealable judgment in any such suit or proceeding shall be conclusive and
may be enforced in other jurisdictions by suit on such judgment or in any other
lawful manner.


                                      -26-
<PAGE>   27

        (b) Counterparts. This Agreement may be executed in two or more
counterparts, all of which shall be considered one and the same agreement and
shall become effective when counterparts have been signed by each party and
delivered to the other party. This Agreement, once executed by a party, may be
delivered to the other parties hereto by facsimile transmission of a copy of
this Agreement bearing the signature of the party so delivering this Agreement.
In the event any signature is delivered by facsimile transmission, the party
using such means of delivery shall cause the manually executed Execution Page(s)
hereof to be physically delivered to the other party within five (5) days of the
execution hereof, provided that the failure to so deliver any manually executed
Execution Page shall not affect the validity or enforceability of this
Agreement.

        (c) Headings. The headings of this Agreement are for convenience of
reference and shall not form part of, or affect the interpretation of, this
Agreement.

        (d) Severability. If any provision of this Agreement shall be invalid or
unenforceable in any jurisdiction, such invalidity or unenforceability shall not
affect the validity or enforceability of the remainder of this Agreement or the
validity or enforceability of this Agreement in any other jurisdiction.

        (e) Entire Agreement; Amendments. This Agreement and the instruments
referenced herein contain the entire understanding of the Purchasers, the
Company, their affiliates and persons acting on their behalf with respect to the
matters covered herein and therein and, except as specifically set forth herein
or therein, neither the Company nor any Purchaser makes any representation,
warranty, covenant or undertaking with respect to such matters. No provision of
this Agreement may be waived other than by an instrument in writing signed by
the party to be charged with enforcement and no provision of this Agreement may
be amended other than by an instrument in writing signed by the Company and each
Purchaser.

        (f) Notices. Any notices required or permitted to be given under the
terms of this Agreement shall be sent by certified or registered mail (return
receipt requested) or delivered personally, by responsible overnight carrier or
by confirmed facsimile, and shall be effective five (5) days after being placed
in the mail, if mailed, or upon receipt or refusal of receipt, if delivered
personally or by responsible overnight carrier or confirmed facsimile, in each
case addressed to a party. The addresses for such communications shall be:


                         If to the Company:

                         ViroLogic, Inc.
                         270 East Grand Avenue
                         South San Francisco, California 94080
                         Telephone:  (650) 635-1100



                                      -27-
<PAGE>   28


                         Attn:  Chief Executive Officer

        with a copy simultaneously transmitted by like means to (which
transmittal shall not constitute notice hereunder):

                         Cooley Godward LLP
                         4365 Executive Drive, Suite 1100
                         San Diego, California 92121
                         Telephone:  (858) 550-6000
                         Attn:  Christopher J. Kearns, Esq.

        If to any Purchaser, to such address set forth under such Purchaser's
name on the Execution Page hereto executed by such Purchaser.

        Each party shall provide notice to the other parties of any change in
address.

        (g) Successors and Assigns. This Agreement shall be binding upon and
inure to the benefit of the parties and their successors and assigns. Except as
provided herein or therein, neither the Company nor any Purchaser shall assign
this Agreement or any rights or obligations hereunder. Notwithstanding the
foregoing, any Purchaser may assign its rights hereunder to any of its
"affiliates," as that term is defined under the Exchange Act, without the
consent of the Company or to any other person or entity with the consent of the
Company, which consent shall not be unreasonably withheld. This provision shall
not limit a Purchaser's right to transfer the Securities pursuant to the terms
of the Certificate of Designation, the Warrants and this Agreement or to assign
such Purchaser's rights hereunder or thereunder to any such transferee. In
addition, and notwithstanding anything to the contrary contained in this
Agreement, the Registration Rights Agreements or the Warrants, the Securities
may be pledged and all rights of any Purchaser under this Agreement or any other
agreement or document related to the transactions contemplated hereby may be
assigned, without further consent of the Company, to a bona fide pledgee in
connection with such Purchaser's margin or brokerage account. In addition and
notwithstanding anything to the contrary contained herein, with respect to the
obligations of SDS Capital (or its affiliates) to purchase shares at the First
Closing or the Second Closing, such Purchasers may assign this Agreement and
their rights and obligations hereunder without the prior consent of the Company
to an affiliate of SDS Capital on or before July 3, 2001, provided that the
assignee or assignees of this Agreement agree in writing to be bound by the
terms, representations and conditions contained in this Agreement.

        (h) Third Party Beneficiaries. This Agreement is intended for the
benefit of the parties hereto and their respective permitted successors and
assigns, and is not for the benefit of, nor may any provision hereof be enforced
by, any other person; provided that Section 4(f) may be enforced by SDS Capital.


                                      -28-
<PAGE>   29


        (i) Survival. The representations and warranties of the Company and the
agreements and covenants set forth in Sections 3, 4, 5 and 8 hereof shall
survive the Closing notwithstanding any due diligence investigation conducted by
or on behalf of any Purchaser. Moreover, none of the representations and
warranties made by the Company herein shall act as a waiver of any rights or
remedies any Purchaser may have under applicable U.S. federal or state
securities laws.

        (j) Publicity. The Company and each Purchaser shall have the right to
approve before issuance any press releases, SEC or NASD filings, or any other
public statements with respect to the transactions contemplated hereby;
provided, however, that the Company shall be entitled, without the prior
approval of the Purchasers, to make any press release or SEC or NASD filings
with respect to such transactions as is required by applicable law and
regulations (although the Purchasers shall be consulted by the Company in
connection with any such press release and filing prior to its release and shall
be provided with a copy thereof).

        (k) Further Assurances. Each party shall do and perform, or cause to be
done and performed, all such further acts and things, and shall execute and
deliver all such other agreements, certificates, instruments and documents, as
the other party may reasonably request in order to carry out the intent and
accomplish the purposes of this Agreement and the consummation of the
transactions contemplated hereby.

        (l) Termination. In the event that the First Closing shall not have
occurred on or before July 31, 2001, unless the parties agree otherwise, this
Agreement shall terminate at the close of business on such date. Notwithstanding
any termination of this Agreement, any party not in breach of this Agreement
shall preserve all rights and remedies it may have against another party hereto
for a breach of this Agreement prior to or relating to the termination hereof.

        (m) Joint Participation in Drafting. Each party to this Agreement has
participated in the negotiation and drafting of this Agreement, the Certificate
of Designation, the Warrants and the Registration Rights Agreements. As such,
the language used herein and therein shall be deemed to be the language chosen
by the parties hereto to express their mutual intent, and no rule of strict
construction will be applied against any party to this Agreement.

        (n) Equitable Relief. The Company acknowledges that a breach by it of
its obligations hereunder will cause irreparable harm to each Purchaser by
vitiating the intent and purpose of the transactions contemplated hereby.
Accordingly, the Company acknowledges that the remedy at law for a breach of its
obligations hereunder (including, but not limited to, its obligations pursuant
to Section 5 hereof) will be inadequate and agrees, in the event of a breach or
threatened breach by the Company of the provisions of this Agreement (including,
but not limited to, its obligations pursuant to Section 5 hereof), that each
Purchaser shall be entitled, in addition to all other available remedies, to an
injunction restraining any breach and requiring


                                      -29-
<PAGE>   30

immediate issuance and transfer of the Securities, without the necessity of
showing economic loss and without any bond or other security being required.

        (o) Additional Acknowledgement. Each Purchaser acknowledges that it has
independently evaluated the merits of the transactions contemplated by this
Agreement, the Certificate of Designation, the Registration Rights Agreements
and the Warrants, that it has independently determined to enter into the
transactions contemplated hereby and thereby, that it is not relying on any
advice from or evaluation by any other Purchaser, and that it is not acting in
concert with any other Purchaser in making its purchase of securities hereunder.
The Purchasers and, to its knowledge, the Company agree that the Purchasers have
not taken any actions that would deem such Purchasers to be members of a "group"
for purposes of Section 13(d) of the Exchange Act.

        (p) Indemnification by Company.

            (i) From and after the First Closing, the Company shall hold
harmless and indemnify each of the Purchasers from and against, and shall
compensate and reimburse each of the Purchasers for, any damages which are
directly or indirectly suffered or incurred by any of the Purchasers or to which
any of the Purchasers may otherwise become subject (regardless of whether or not
such damages relate to any third-party claim) and which arise from or as a
result of, or are directly or indirectly connected with any inaccuracy in or
breach of any of the Company's representations, warranties or covenants set
forth herein.

            (ii) In the event of the assertion or commencement by any person of
any claim or legal proceeding with respect to which any Purchaser may have
indemnification rights pursuant to Section 8(p)(i), such Purchaser shall
promptly notify the Company thereof in writing, but the failure to so notify the
Company will not limit any Purchaser's rights to indemnification hereunder,
except to the extent the Company demonstrates that the defense of such action is
prejudiced by the failure to so give such notice.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]



                                      -30-
<PAGE>   31

        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.

VIROLOGIC, INC.

        By: /s/ WILLIAM D. YOUNG
           ----------------------------

        Name: William D. Young
             --------------------------

        Title: Chief Executive Officer
              -------------------------


PURCHASER:

S.A.C. CAPITAL ASSOCIATES, LLC

By:  S.A.C. Capital Advisors, LLC

     By: /s/ PETER NUSSBAUM
         -----------------------------
         Name: Peter Nussbaum
         Title: General Counsel



RESIDENCE:       Anguilla

ADDRESS:         c/o S.A.C. Capital Advisors, LLC
                 777 Long Ridge Road
                 Stamford, CT 06902
                 Telecopy:  (203)-614-2393
                 Telephone:  (203) 614-2000
                 Attention:  Peter Nussbaum

                 with a copy to:

                 Klehr, Harrison, Harvey, Branzburg & Ellers LLP
                 260 South Broad Street
                 Philadelphia, PA  19102
                 Telecopy:  (215) 568-6603
                 Attention:  Stephen T. Burdumy, Esquire


AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                           First Closing       Second Closing
                                           -------------       --------------
<S>                                       <C>                  <C>
Number of Units:                                   143                 207
                                            ----------          ----------
Purchase Price ($10,000 per Unit):          $1,430,000          $2,070,000
                                            ----------          ----------
</TABLE>



<PAGE>   32

        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.


VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------



PURCHASER:

SDS MERCHANT FUND, L.P.

By:   /s/ STEVE DERBY
    ----------------------------
      Name: Steve Derby
      Title: Managing Member


RESIDENCE:       Connecticut


ADDRESS:         One Sound Drive
                 Second Floor
                 Greenwich, CT 06830
                 Telecopy:  (212) 656-1810
                 Attention:  Steve Derby

                 with a copy to:

                 Klehr, Harrison, Harvey, Branzburg & Ellers LLP
                 260 South Broad Street
                 Philadelphia, PA  19102
                 Telecopy:  (215) 568-6603
                 Attention:  Stephen T. Burdumy, Esquire



AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                         First Closing      Second Closing
                                         -------------      --------------
<S>                                     <C>                <C>
Number of Units:                                  61                89
                                            --------          --------
Purchase Price ($10,000 per Unit):          $610,000          $890,000
                                            --------          --------
</TABLE>


<PAGE>   33
'
        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.

VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------


PURCHASER:

NARRAGANSETT I, L.P.

By: /s/ J. L. DOWLING III
    ----------------------------
    Name: Joseph L. Dowling III
    Title: Managing Member

RESIDENCE:

ADDRESS:         153 E. 53rd Street
                 26th Floor
                 New York, NY 10022
                 Telecopy:  (212) 521-5029
                 Attention:  Janeen Prosek

                 with a copy to:

                 Klehr, Harrison, Harvey, Branzburg & Ellers LLP
                 260 South Broad Street
                 Philadelphia, PA  19102
                 Telecopy:  (215) 568-5005
                 Attention:  Stephen T. Burdumy, Esquire



AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                          First Closing     Second Closing
                                          -------------     --------------
<S>                                      <C>               <C>
Number of Units:                                  67                98
                                            --------          --------
Purchase Price ($10,000 per Unit):          $670,000          $980,000
                                            --------          --------
</TABLE>


<PAGE>   34

        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.


VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------


PURCHASER:


NARRAGANSETT OFFSHORE, LTD.

By: /s/ J.L. DOWLING III
    ----------------------------
    Name: Joseph L. Dowling III
    Title: Managing Member



RESIDENCE:

ADDRESS:         153 E. 53rd Street
                 26th Floor
                 New York, NY 10022
                 Telecopy:  (222) 521-5005
                 Attention:  Janeen Prosek

                 with a copy to:

                 Klehr, Harrison, Harvey, Branzburg & Ellers LLP
                 260 South Broad Street
                 Philadelphia, PA  19102
                 Telecopy:  (215) 568-6603
                 Attention:  Stephen T. Burdumy, Esquire



AGGREGATE SUBSCRIPTION AMOUNT

<TABLE>
<CAPTION>
                                           First Closing      Second Closing
                                           -------------      --------------
<S>                                        <C>                <C>
Number of Units:                                   137                 198
                                            ----------          ----------
Purchase Price ($10,000 per Unit):          $1,370,000          $1,980,000
                                            ----------          ----------
</TABLE>


<PAGE>   35

        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.

VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------



PURCHASER:


CASTLE CREEK HEALTHCARE PARTNERS, L.P.

By: /s/ THOMAS A. FREI
    ----------------------------
    Name:  Thomas A. Frei
    Title: Managing Director


RESIDENCE:

ADDRESS:         c/o Castle Creek Partners, LLC
                 111 West Jackson Blvd., Suite 2020
                 Chicago, IL 60604
                 Telecopy:
                 Attention:

                 with a copy to:

                 Klehr, Harrison, Harvey, Branzburg & Ellers LLP
                 260 South Broad Street
                 Philadelphia, PA  19102
                 Telecopy:  (215) 568-6603
                 Attention:  Stephen T. Burdumy, Esquire



AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                         First Closing     Second Closing
                                         -------------     --------------
<S>                                     <C>               <C>
Number of Units:                                  31                44
                                            --------          --------
Purchase Price ($10,000 per Unit):          $310,000          $440,000
                                            --------          --------
</TABLE>


<PAGE>   36

        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.


VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------



PURCHASER:

CCL FUND LLC


By: /s/ FRED GOLDMAN
    ----------------------------
    Name:  Fred Goldman
    Title: Member of the Manager



RESIDENCE:

ADDRESS:         c/o Castle Creek Partners, LLC
                 111 West Jackson Blvd., Suite 2020
                 Chicago, IL 60604
                 Telecopy:
                 Attention:

                 with a copy to:

                 Klehr, Harrison, Harvey, Branzburg & Ellers LLP
                 260 South Broad Street
                 Philadelphia, PA  19102
                 Telecopy:  (215) 568-6603
                 Attention:  Stephen T. Burdumy, Esquire

AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                          First Closing     Second Closing
                                          -------------     --------------
<S>                                      <C>               <C>
Number of Units:                                  31                44
                                            --------          --------
Purchase Price ($10,000 per Unit):          $310,000          $440,000
                                            --------          --------
</TABLE>


<PAGE>   37


        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.



VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------



PURCHASER:


CRESTWOOD CAPITAL PARTNERS, L.P.


By: ING FURMAN SELZ ASSET MANAGEMENT, LLC



    By: /s/ MICHAEL WEISBERG
        ----------------------------
        Name: Michael Weisberg
        Title:



RESIDENCE:       New York

ADDRESS:         230 Park Avenue
                 13th Floor
                 New York, NY 10169
                 Telecopy:  (212) 808-2614
                 Attention:  Michael Weisberg




AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                          First Closing        Second Closing
                                          -------------        --------------
<S>                                      <C>                  <C>
Number of Units:                                    90                 130
                                            ----------          ----------
Purchase Price ($10,000 per Unit):          $  900,000          $1,300,000
                                            ----------          ----------
</TABLE>


<PAGE>   38

        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.


VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------


PURCHASER:

CRESTWOOD CAPITAL INTERNATIONAL, L.P.

By: ING FURMAN SELZ ASSET MANAGEMENT, LLC

       By: /s/ ROBERT J. MILLER
           ----------------------------
           Name: Robert J. Miller
           Title:

RESIDENCE:       British Virgin Islands

ADDRESS:         230 Park Avenue
                 13th Floor
                 New York, NY 10169
                 Telecopy:  (212) 808-2614
                 Attention:  Michael Weisberg



AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                          First Closing     Second Closing
                                          -------------     --------------
<S>                                       <C>              <C>
Number of Units:                                  51                73
                                            --------          --------
Purchase Price ($10,000 per Unit):          $510,000          $730,000
                                            --------          --------
</TABLE>


<PAGE>   39


        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.



VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------



PURCHASER:

CRESTWOOD CAPITAL PARTNERS II, L.P.

By: ING FURMAN SELZ ASSET MANAGEMENT, LLC


       By: /s/ MICHAEL WEISBERG
           ----------------------------
           Name: Michael Weisberg
           Title:



RESIDENCE:       New York

ADDRESS:         230 Park Avenue
                 13th Floor
                 New York, NY 10169
                 Telecopy:  (212) 808-2614
                 Attention:  Michael Weisberg


AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                         First Closing      Second Closing
                                         -------------      --------------
<S>                                     <C>                <C>
Number of Units:                                  10                19
                                            --------          --------
Purchase Price ($10,000 per Unit):          $100,000          $190,000
                                            --------          --------
</TABLE>


<PAGE>   40

        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.


VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------



PURCHASER:

BRIDGEWOOD CAPITAL PARTNERS, L.P.

By: ING FURMAN SELZ ASSET MANAGEMENT, LLC

        By: /s/ MICHAEL WEISBERG
           ----------------------------
           Name: Michael Weisberg
           Title:



RESIDENCE:       New York

ADDRESS:         230 Park Avenue
                 13th Floor
                 New York, NY 10169
                 Telecopy:  (212) 808-2614
                 Attention:  Michael Weisberg



AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                         First Closing     Second Closing
                                         -------------     --------------
<S>                                     <C>               <C>
Number of Units:                                  13                19
                                            --------          --------
Purchase Price ($10,000 per Unit):          $130,000          $190,000
                                            --------          --------
</TABLE>


<PAGE>   41


        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.


VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------



PURCHASER:

ANVERS HEALTHCARE INVESTORS, L.P.

By: ING FURMAN SELZ ASSET MANAGEMENT, LLC

        By: /s/ LESLIE HENSHAW
           ----------------------------
           Name: Leslie Henshaw
           Title: Managing Director


RESIDENCE:       New York

ADDRESS:         230 Park Avenue
                 13th Floor
                 New York, NY 10169
                 Telecopy:  (212) 309-1719
                 Attention:  Leslie Henshaw



AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                         First Closing     Second Closing
                                         -------------     --------------
<S>                                     <C>               <C>
Number of Units:                                  21                29
                                            --------          --------
Purchase Price ($10,000 per Unit):          $210,000          $290,000
                                            --------          --------
</TABLE>


<PAGE>   42


        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.



VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------


PURCHASER:

ANVERS II, L.P.

By: ING FURMAN SELZ ASSET MANAGEMENT, LLC


       By: /s/ LESLIE HENSHAW
           ----------------------------
           Name: Leslie Henshaw
           Title: Managing Director



RESIDENCE:       New York

ADDRESS:         230 Park Avenue
                 13th Floor
                 New York, NY 10169
                 Telecopy:  (212) 309-1719
                 Attention:  Leslie Henshaw


AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                         First Closing    Second Closing
                                         -------------    --------------
<S>                                        <C>              <C>
Number of Units:                                  4                6
                                            -------          -------
Purchase Price ($10,000 per Unit):          $40,000          $60,000
                                            -------          -------
</TABLE>


<PAGE>   43


        IN WITNESS WHEREOF, the undersigned Purchaser and the Company have
caused this Agreement to be duly executed as of the date first above written.



VIROLOGIC, INC.

        By:
           ----------------------------

        Name:
             --------------------------

        Title:
              -------------------------



PURCHASER:

ANVERS, L.P.

By: ING FURMAN SELZ ASSET MANAGEMENT, LLC


       By:  /s/ LESLIE HENSHAW
           ----------------------------
           Name: Leslie Henshaw
           Title: Managing Director


RESIDENCE:       New York

ADDRESS:         230 Park Avenue
                 13th Floor
                 New York, NY 10169
                 Telecopy:  (212) 808-2614
                 Attention:  Leslie Henshaw


AGGREGATE SUBSCRIPTION AMOUNT


<TABLE>
<CAPTION>
                                         First Closing     Second Closing
                                         -------------     --------------
<S>                                     <C>               <C>
Number of Units:                                  6                9
                                            -------          -------
Purchase Price ($10,000 per Unit):          $60,000          $90,000
                                            -------          -------
</TABLE>