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                                                                   FINOVA
                                                            FINANCIAL INNOVATORS


                                                      FINOVA Capital Corporation
                                                              10 Waterside Drive
                                                       Farmington, CT 06032-3065
                                                                  (860) 676-1818




                       MASTER LOAN AND SECURITY AGREEMENT



Master Loan and Security Agreement No. S7250                 Dated July 23, 1999


FINOVA Capital Corporation ("we," "us" or "FINOVA"), having its principal place
of business at 1850 North Central Avenue, Phoenix, Arizona 85004 is willing to
make a loan (the "Loan") to Aviron, Inc. ("you" or "Borrower"), having its
principal place of business at 297 N. Bernardo Avenue, Mountain View, California
94043 in one or more advances made from time to time (individually, an "Advance"
and collectively, the "Advances"), in the aggregate principal amount of up to
Seventeen Million Dollars ($17,000,000), under the terms and conditions
contained in this Master Loan and Security Agreement (this "Master Agreement").
The entire Loan will be "cross collateralized" and secured by the collateral
(the "Collateral") described in each schedule (individually, a "Schedule" and
collectively, "Schedules") which will be executed in connection with each
Advance and the related Note (as hereinafter defined). The Collateral includes
the FF&E hereinafter described and any and all replacement parts, additions,
accessories and accessions that you may add to the FF&E, as well as all
replacements and substitutions of the FF&E and all proceeds of the FF&E,
including, without limitation, insurance proceeds. We may treat any Schedule as
a separate loan and security agreement containing all of the provisions of this
Master Agreement.

1.    THE CREDIT

     (a)  ADVANCES. Each Advance shall be evidenced by and the specific terms
          applicable thereto set forth in a Note and related Schedule. All of
          the Notes and Schedules, taken together, will evidence the entire
          Loan. We will only make the Loan to you if all the conditions in this
          Master Agreement have been met to our satisfaction. We will rely on
          your representations and warranties contained in this Master
          Agreement, in making the Loan. The terms of this Master Agreement will
          each apply to the entire Loan.

     (b)  USE OF PROCEEDS. The proceeds of the Advances will be used solely to
          reimburse you for your payment of the acquisition, construction and
          installation of the machinery, equipment, fixtures, leasehold
          improvements and other assets acquired, constructed and/or financed
          with the proceeds of any Advance and the Loan, all of which shall be
          satisfactory to us and which is described in the applicable Schedule
          ("FF&E"). If you have not yet paid for the FF&E (but the same is
          otherwise satisfactory to us), the proceeds of the Advance will be
          paid by us directly to the supplier or contractor (which you have
          chosen) to pay the purchase price or cost of the FF&E.

     (c)  NOTES. Your obligation to repay the Advance and to pay interest
          thereon will


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          be evidenced by separate secured promissory notes (individually, a
          "Note" and collectively, the "Notes"). Each Note will be dated the
          date of the Schedule to which the Advance evidenced by the Note is
          related. The related Schedule will be deemed to be part of the Note.

     (d)  TERM. The term ("Term") of each Schedule (and the related Advance)
          begins upon the date that we make payment for the Collateral covered
          under the Schedule (the "Closing Date"). The Term continues until you
          fully perform all of your obligations under this Master Agreement,
          each related Schedule and the related Note(s).

     (e)  LOAN ACCOUNT. We will keep a loan account on our books and records for
          the Loan. We will record all payments of principal and interest in the
          loan account. Unless the entries in the loan account are clearly in
          error, the loan account will definitively indicate the outstanding
          principal balance and accrued interest on the Loan.

     (f)  PAYMENTS. The scheduled payments of principal and interest (the
          "Payments") are indicated on and due and payable in accordance with
          the terms of the applicable Note and Schedule. The Payments are
          payable in advance and otherwise on the dates and in the amounts set
          forth on the applicable Schedule.

     (g)  FIRST PAYMENT AND SUBSEQUENT PAYMENTS. The first Payment under a Note
          and Advance ("First Payment") is due at the beginning of its Term and
          shall, at our option, either be deducted from the proceeds of the
          Advance or paid directly to us by you. Subsequent Payments are due on
          the thirtieth (30th) day of each successive month as set forth on the
          Schedule until you pay to us in full all of the Payments and any other
          fees, costs, charges and expenses that you owe us.

     (h)  INTEREST. Prior to Maturity of an Advance, you will pay us interest on
          the Advance at the interest rate indicated in the applicable Schedule
          (the "Interest Rate"). "Maturity" means the scheduled maturity or any
          earlier date on which we accelerate the Loan. The Payment amount
          indicated in the Schedule includes interest at the applicable Interest
          Rate. Interest is calculated in advance using a year of 360 days with
          twelve months of 30 days.

     (i)  INTERIM INTEREST PAYMENT. If an Advance is made on a day other than
          the thirtieth (30th) or thirty-first (31st) day of a month, you will
          also pay to us, together with the First Payment, interest on the
          Advance at the applicable interest rate for the period from the date
          the Advance is made until the twenty-ninth (29th) day of the month in
          which the Advance is made. If an Advance is made on the thirty-first
          (31st) day of a month, you will also pay to us, together with the
          First Payment, interest on the Advance at the applicable interest rate
          for the period from the date the Advance is made until the
          twenty-ninth (29th) day of the following month. If an Advance is made
          on the thirtieth (30th) day of a month, no interim interest will be
          due.

     (j)  DEFAULT INTEREST RATE. After Maturity of the Loan or any Advance, you
          will pay us interest thereon at a rate of four (4%) percent per year
          above the applicable Interest Rate. This is referred to as the
          "Default Rate."

     (k)  USURY. You and we intend to obey the law. If the Interest Rate charged
          would exceed the maximum legal rate, you will only have to pay the
          maximum legal rate. You do not have to pay any excess interest over
          and above the maximum legal rate of interest. However, if it later
          becomes legal for you to pay all or part of any excess interest, you
          will then pay it to us upon our request.



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     (l)  PAYMENT DETAILS. You will make all Payments due under this Master
          Agreement by 2:00 P.M., Connecticut time, on the day they are due. You
          will make all Payments in US Dollars (US$) in immediately available
          funds. We do not have to make or give "presentment, demand, protest or
          notice" to get paid. You waive "presentment, demand, protest and
          notice."

     (m)  APPLICATION OF PAYMENTS. Each Payment under this Master Agreement is
          to be applied in the following order: first, to any fees, costs,
          expenses and charges you may owe us; second, to any interest due; and
          third to the principal balance.

     (n)  PREPAYMENT. You may not prepay the Loan or any Advance, in whole or in
          part, unless this is specifically permitted by Exhibit B to the
          applicable Schedule.

     (o)  NO SETOFFS. Your obligation to pay us all Payments is absolute and
          unconditional. You are not excused from making the Payments, in full,
          for any reason. You agree that you have no defense for failure to make
          the Payments and you will not make any counterclaims or setoffs to
          avoid making the Payments.

2.   SECURITY INTEREST

     (a)  You grant us a first and only lien (subject only to Permitted Liens,
          as hereinafter defined) on and security interest in the Collateral.
          The Collateral secures the full and timely payment and performance of
          all of your now existing or hereafter arising indebtedness,
          liabilities and obligations to us, whether under this Master
          Agreement, the Schedules, the Notes and any other agreement, loan or
          lease that you may at any time or times have with us or otherwise
          (collectively, the "Obligations"). You also grant us a security
          interest in any additional collateral identified in any Schedule. Any
          additional collateral is considered to be "Collateral" and it secures
          all of the Obligations.

     (b)  If we request, you will put labels supplied by us stating "PROPERTY
          SUBJECT TO A SECURITY INTEREST HELD BY FINOVA CAPITAL CORPORATION" on
          the Collateral where they are clearly visible.

     (c)  You give us permission to add to this Master Agreement or any Schedule
          the serial numbers and other information about the Collateral.

     (d)  You give us permission to file this Master Agreement or Uniform
          Commercial Code financing statements, at your expense, in order to
          perfect our security interest in the Collateral. You also give us
          permission to sign your name on the Uniform Commercial Code financing
          statements where this is permitted by law.

     (e)  You will pay our reasonable fees and costs for documentation, closing,
          administration and termination of this Master Agreement, the Notes and
          Schedules. Notwithstanding the foregoing, you will pay such fees and
          expenses incurred in connection with the transaction, including the
          fees and expenses of counsel to prepare, review and negotiate the
          documentation and close the transaction, up to a maximum of $7,000.
          Any fees and expenses in excess of $7,000 will be shared equally by
          FINOVA and you. These fees include such items as reasonable attorneys
          fees and expenses incurred in preparing this Master Agreement and all
          agreements, instruments and documents executed in connection herewith,
          and all amendments, supplements and waivers hereto and thereto, as
          well as due diligence searches and fees for preparing and filing UCC
          terminations and releases. You will also pay any filing, recording or
          stamp fees or taxes resulting from filing this Master



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          Agreement or a Uniform Commercial Code financing statements.

     (f)  At your expense, you will defend our first priority security interest
          in the Collateral against, and keep the Collateral free of, any legal
          process, liens, other security interests, attachments, levies and
          executions, other than Permitted Liens. You will give us immediate
          written notice of any legal process, liens, attachments, levies or
          executions, and you will indemnify us against any loss that results to
          us from these causes.

     (g)  You will notify us at least 15 days before you change the address of
          your principal executive office or principal place of business. Your
          principal executive office and principal place of business are set
          forth at the beginning of this Master Agreement.

     (h)  You will promptly sign and return additional documents that we may
          reasonably request in order to protect our first priority security
          interest in the Collateral.

     (i)  Except as set forth in a Schedule, the Collateral is personal property
          and will remain personal property. Except as set forth in a Schedule,
          you will not incorporate it into real estate and will not do anything
          that will cause the Collateral to become part of real estate or a
          fixture.

3.   CONDITIONS OF LENDING

     (a)  See our Commitment Letter to you dated May 6, 1999 (the "Commitment
          Letter"), which you and we consider to be a part of this Master
          Agreement. The terms and conditions of the Commitment Letter continue
          following the making of the first Advance, including, without
          limitation, conditions to the Loan. However, if there is a conflict
          between the terms and conditions of this Master Agreement, any
          Schedule or any Note and the terms and conditions of the Commitment
          Letter, then you and we agree that the terms and conditions of this
          Master Agreement, the Schedules and the Notes control over the
          Commitment Letter terms and conditions.

     (b)  Before we disburse any proceeds of any Advance, we also require the
          following:

          (i)   That no payment is past due to us under any other agreement,
                loan or lease that you have with us.

          (ii)  That you are complying with all terms of this Master Agreement,
                the Schedules and the Notes and there are no defaults hereunder
                or thereunder.

          (iii) That we have received all the documents we requested, including
                the signed Schedule and Note.

          (iv)  That there has been no material adverse change in your financial
                condition, business or operations, from the financial condition
                that you have disclosed to us.

          (v)   All conditions contained in the Commitment Letter have been
                satisfied.

4.   REPRESENTATIONS AND WARRANTIES

You represent and warrant to us as follows:

     (a)  You are duly organized, existing and in good standing wherever you or
          it are required by law to be so qualified. You have full power and
          authority to execute, deliver and carry out the provisions of this
          Master Agreement, the Schedules and the Notes and to borrow hereunder
          and thereunder. This Master Agreement, the Schedules and the Notes are
          validly executed and delivered by you and are the legal, valid and
          binding obligations of



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          you, each enforceable in accordance with its terms.

     (b)  Except as disclosed in a Schedule, you are not a defendant under any
          material litigation and there are no judgments outstanding against
          you.

     (c)  All of the FF&E has been delivered to you and installed at the
          location set forth on the Schedule and you have accepted all of the
          FF&E for all purposes of this Master Agreement.

     (d)  You have good title to all of your assets, including, without
          limitation, the Collateral, and in the case of the Collateral, free
          and clear of all security interests, liens and other encumbrances,
          except for Permitted Liens. Upon filing of UCC-1 financing statements
          in all applicable filing offices, we will be granted a first and only
          (except for Permitted Liens) perfected lien on and security interest
          in all of the Collateral. There are no other security interests, liens
          or encumbrances covering the Collateral, except for Permitted Liens.
          For purposes of this Master Agreement, "Permitted Liens" means (i)
          liens for taxes, assessments and other governmental charges or levies
          or the claims or demands of landlords, carriers, warehousemen,
          mechanics, laborers, materialmen and other like persons arising by
          operation of law in the ordinary course of business for sums which are
          not yet due and payable; (ii) liens to secure the payment of sums
          which are not yet due and payable incurred in the ordinary course of
          business with respect to workers' compensation, unemployment insurance
          or other social security benefits or obligations, public or statutory
          obligations; (iii) liens in favor of FINOVA; and (iv) liens in favor
          of customs and revenue authorities arising as a matter of law to
          secure payments of customs duties in connection with the importation
          of goods, which liens are limited to the extent that such assets are
          in the possession of customs authorities..

     (e)  You have supplied us with information about the Collateral. You
          promise to us that the amount of our Advance as to each item of FF&E
          is no more than the fair and usual price for this kind of FF&E, taking
          into account any discounts, rebates and allowances that you or any
          affiliate of yours may have been given for the FF&E.

     (f)  The Collateral is located at the premises set forth on the Schedule.

     (g)  All financial information and other information that you have given us
          is true and complete. You have not failed to tell us anything that
          would make the financial information not misleading. There has been no
          material adverse change in your financial condition, business or
          operations, from the financial condition, business or operations that
          you disclosed to us.

     (h)  You have complied with all "environmental laws" and will continue to
          comply with all "environmental laws," except where noncompliance could
          not reasonably be expected to have a material adverse effect on the
          business, property or assets, condition (financial or otherwise) or
          operations of you and your subsidiaries. No "hazardous substances" are
          used, generated, treated, stored or disposed of by you or at your
          properties except in compliance with all environmental laws.
          "Environmental laws" mean all federal, state or local environmental
          laws and regulations, including the following laws: CERCLA, RCRA,
          Hazardous Materials Transport Act and The Federal Water Pollution
          Control Act. "Hazardous substances" means all hazardous or toxic
          wastes, materials or substances, as defined in the environmental laws,
          as well as oil, flammable substances, asbestos that is or



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          could become friable, urea formaldehyde insulation, polychlorinated
          biphenyls and radon gas.

5.   COVENANTS

You agree to do the following things (or not to do the following things if so
stated) until full payment of all amounts due to us under this Master Agreement,
the Schedules and the Notes:

     (a)  CARE, USE, LOCATION, TRANSFER, ENCUMBRANCE AND ALTERATION OF THE
          COLLATERAL.

          (i)   You will make sure that the Collateral is maintained in good
                operating condition (ordinary wear and tear excepted), and that
                it is serviced, repaired and overhauled when this is necessary
                to keep the Collateral in good operating condition. All
                maintenance must be done according to the Supplier's or
                Manufacturer's requirements or recommendations. All maintenance
                must also comply with any legal or regulatory requirements.

          (ii)  You will maintain service logs for the Collateral, if
                applicable, and permit us or our agents to inspect the
                Collateral, the service logs and service reports. You give us
                and our agents permission to make copies of the service logs and
                service reports.

          (iii) We will give you prior notice if we, or our agents, want to
                inspect the Collateral or the service logs or service reports.
                We may inspect it during regular business hours. If we find
                during an inspection that you are not complying with this Master
                Agreement or if you are otherwise in default under this Master
                Agreement, you (and not we) will pay our travel, meals and
                lodging costs, our salary costs, and our costs and fees and
                those of our agents for reinspection. You will promptly cure any
                problems with the Collateral that are discovered during our
                inspections.

          (iv)  You will use the Collateral only for business purposes. You will
                obey all legal and regulatory requirements in your use of the
                Collateral, except where noncompliance could not reasonably be
                expected to have a material adverse effect on the business,
                property or assets, condition (financial or otherwise) or
                operations of you and your subsidiaries.

          (v)   You will make all additions, modifications and improvements to
                the Collateral that are required by law or government
                regulation. Otherwise, you will not alter the Collateral without
                our written permission. You will replace all worn, lost, stolen
                or destroyed parts of the Collateral with replacement parts that
                are as good or better than the original parts. The new parts
                will become subject to our security interest upon replacement.

          (vi)  You will not remove the Collateral from the location indicated
                in the Schedule, provided, however, that you may move the
                Collateral presently located at such location to another
                location located in the continental United States, but if and
                only if (a) you shall have given us not less than thirty (30)
                days prior written notice of the



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          actual move and a list of all Collateral being so moved, (b) there is
          then no default hereunder, (c) if the new location is leased, prior to
          such move, we shall have received a Landlord Waiver executed by the
          landlord of the new location, said Landlord Waiver to be in form and
          substance satisfactory to us, (d) we shall have been granted a first
          perfected lien and security interest on such moved Collateral and
          there shall be no other liens covering such Collateral (other than
          Permitted Liens), (e) you shall have executed and delivered to us all
          such agreements, instruments and documents reasonably requested by us
          in connection therewith, and (f) we shall have received satisfactory
          results of all due diligence searches (including, without limitation,
          environmental audits).

          (vii)  You have and will have good and merchantable title to all of
                 the Collateral.

          (viii) You will not convey, assign, sell, mortgage, transfer,
                 encumber, pledge, hypothecate, grant a security interest in,
                 grant options with respect to, lease or otherwise dispose of
                 all or any part of any interest whatsoever in or to any or all
                 of the Collateral, or any interest therein.

     (b)  YEAR 2000 COMPLIANT.

          You represent, warrant and agree to take all action necessary,
          including, but not limited to, due inquiry and due diligence with
          critical business partners to assure that there will be no material
          adverse change to your business by reason of the advent of the year
          2000, including, without limitation, that all computer-based systems,
          embedded microchips and other processing capabilities effectively
          recognize and process all dates before and after December 31, 1999
          ("Y2K Compliant"). At our request, you shall provide to us assurance
          reasonably acceptable to us that your computer-based systems, embedded
          microchips and other processing capabilities are Y2K Compliant.

     (c)  RISK OF LOSS.

          (i)   You have the complete risk of loss or damage to the Collateral.
                Loss or damage to the Collateral will not relieve you of your
                obligation to make the Payments.

          (ii)  If any Collateral is lost or damaged, you have two choices
                although if you are in default under this Master Agreement, we
                and not you will have the two options). The choices are:

                (A)  Repair or replace the damaged or lost Collateral so that,
                     once again, the Collateral is in good operating condition
                     and we have a perfected first priority security interest in
                     it.

                (B)  Pay us the present value (as of the date of payment) of the
                     remaining Payments. We will calculate the present value
                     using a discount rate of five (5%) percent per year. Once
                     you have paid us this amount and any other amount that you
                     may owe us, we will release our security interest in the
                     damaged or lost Collateral and you (or your insurer)



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                     may keep the Collateral for salvage purposes, on an "AS IS,
                     WHERE IS" basis and without any representation or warranty
                     whatsoever.

     (d)  INSURANCE.

          (i)   Until you have made all Payments to us under this Master
                Agreement, the Schedules and the Notes and all Obligations have
                been satisfied in full, you will keep the Collateral insured.
                The amount of insurance, the coverage, and the insurance company
                must be acceptable to us.

          (ii)  If you do not provide us with written evidence of insurance that
                is acceptable to us, we may buy the insurance ourselves, at your
                expense. You will promptly pay us the cost of this insurance. We
                have no obligation to purchase any insurance. Any insurance that
                we purchase will be our insurance, and not yours, and we may
                insure the Collateral beyond the date of satisfaction of the
                Obligations.

          (iii) Insurance proceeds may be used to repair or replace damaged or
                lost Collateral or to pay us the present value of the Payments,
                as provided above.

          (iv)  You appoint us as your "attorney-in-fact" to make claims under
                the insurance policies, to receive payments under the insurance
                policies, and to endorse your name on all documents, checks or
                drafts relating to insurance claims for Collateral.

     (e)  TAXES.

          (i)   You will pay all sales, use, excise, stamp, documentary and ad
                valorum taxes, license, recording and registration fees,
                assessments, fines, penalties and similar charges imposed on the
                ownership, possession, use, lease or rental of the Collateral or
                on the Loan.

          (ii)  You will pay all taxes (other than our federal or state net
                income taxes) imposed on you or on us regarding the Payments.

          (iii) You will reimburse us for any of these taxes that we pay or
                advance.

          (iv)  You will file and pay for any personal property taxes on the
                Collateral.

     (f)  INFORMATION SUPPLIED BY YOU.

          (i)   During the Term you will promptly provide us with copies of any
                current, quarterly and annual reports and all proxy (or
                information) statements you file with the Securities and
                Exchange Commission ("SEC").

          (ii)  You will also provide us with the following financial
                statements:

                (A)  Quarterly balance sheet and statements of earnings and cash
                     flow - within 45 days after the end of your first three
                     fiscal quarters in each fiscal year. These will be
                     certified by the chief financial officer.

                (B)  Annual balance sheet and statements of



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                     earnings and cash flow - within 90 days after the end of
                     each fiscal year. These will be audited by independent
                     auditors acceptable to us. Their audit report must be
                     unqualified.

          All financial statements will be prepared according to generally
          accepted accounting principles, consistently applied. The consolidated
          balance sheets of the Borrower and its subsidiaries as of the date
          thereof, and the statements of income and cash flows fairly present
          the results of the operations of the Borrower and its subsidiaries and
          their cash flows for the periods indicated. The SEC filings that you
          provide us will not contain any untrue statement of a material fact or
          omit to state a material fact necessary in order to make the
          statements contained therein not misleading.

          (iii) At the same time you deliver the financial statements described
                in paragraph 5(f)(ii)(A), you will also provide us with a
                certificate of your chief financial officer stating that no
                default exists, or, if he cannot certify this because a default
                does exist, he must specify in reasonable detail the nature of
                the default.

          (iv)  The audited financial statements described in paragraph
                5(f)(ii)(B), must be accompanied by a certificate of such
                independent auditor stating that no default exists, or, if it
                cannot certify this because a default does exist, it must
                specify in reasonable detail the nature of the default.

     (g)  MINIMUM CASH COVENANT.

          You shall at all times maintain a cash balance (cash and marketable
          securities) of not less than $20,000,000. You shall deliver to us,
          monthly, on the 10th day of each month, a copy of your bank and/or
          securities statements or other documents satisfactory to us evidencing
          such cash balance, which evidence shall be certified by your Chief
          Financial Officer as being complete, true and accurate. If the cash
          balance for any one month is less than $20,000,000, you shall cause to
          have issued and delivered to us an irrevocable standby letter of
          credit (in form and substance satisfactory to us and issued by a bank
          satisfactory to us) in our favor as beneficiary, in an amount equal to
          the then outstanding principal balance of the Loan and all accrued
          interest thereon. Thereafter, it shall be an additional condition to
          the making of each further Advance, that you shall have caused to be
          issued and delivered to us an additional irrevocable standby letter of
          credit (each in form and substance satisfactory to us and issued by a
          bank satisfactory to us) in our favor as beneficiary, each in an
          amount equal to the requested Advance. Each letter of credit shall
          provide for automatic renewal annually for the entire Term of the Loan
          and shall permit us to draw in full if any such letter of credit is
          not so renewed or if a new letter of credit (satisfactory to us issued
          by a bank satisfactory to us) is not substituted at least sixty (60)
          days prior to the expiration of any such letter of credit. The failure
          to provide any such letter of credit or if any such letter of credit
          shall at any time cease to be in full force and effect, shall be a
          default under this Master Agreement.

6.   DEFAULTS

     (a)  DEFAULTS. You are in default if any of the



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          following happens:

          (i)    You do not pay us, within five (5) business days of the date
                 when it is due, any Payment or other amount that you owe us
                 under this Master Agreement, any Schedule or any Note or that
                 you owe us under any other agreement, loan, lease or other
                 financial arrangement that you have with us.

          (ii)   Any of the financial information that you give us is not true
                 and complete, or you fail to tell us anything that would make
                 the financial information not misleading.

          (iii)  You do something you are not permitted to do, or you fail to
                 do, within fifteen (15) days of the date required for
                 performance, anything that is required of you, under this
                 Master Agreement, any Schedule or any other lease, loan or
                 other financial arrangement that you have with us.

          (iv)   An event of default occurs for any other lease, loan or
                 obligation of yours that exceeds $100,000 in the aggregate.

          (v)    You file bankruptcy, or involuntary bankruptcy is filed against
                 you and such involuntary bankruptcy is not dismissed within
                 sixty (60) days.

          (vi)   You are subject to any other insolvency proceeding other than
                 bankruptcy (for example, a receivership action or an assignment
                 for the benefit of creditors) and such proceeding that is
                 involuntary is not dismissed within sixty (60) days.

          (vii)  Without our permission, you sell all or a substantial part of
                 your assets, merge or consolidate, or a majority of your voting
                 stock or interests is transferred.

          (viii) There is a material adverse change in your financial condition,
                 business or operations.

     (b)  REMEDIES, DEFAULT INTEREST, LATE FEES. If you are in default we may
          exercise one or more of our "remedies." Each of our remedies is
          independent. We may exercise any of our remedies, all of our remedies
          or none of our remedies. We may exercise them in any order we choose.
          Our exercise of any remedy will not prevent us from exercising any
          other remedy or be an "election of remedies." If we do not exercise a
          remedy, or if we delay in exercising a remedy, this does not mean that
          we are forgiving your default or that we are giving up our right to
          exercise the remedy. Our remedies allow us to do one or more of the
          following:

          (i)    "Accelerate" the Loan balance under any or all Notes. This
                 means that we may require you to immediately pay us the entire
                 outstanding principal balance of the entire Loan.

          (ii)   Require you to immediately pay us all amounts that you are
                 required to pay us for the entire Term of any other agreements,
                 loans, leases or financial arrangements that you have with us.

          (iii)  Sue you for the entire outstanding principal balance of the
                 Loan and all other amounts you owe us (including, without
                 limitation, all accrued and unpaid interest, including interest
                 at the Default Rate), outstanding fees,



                                      -10-
<PAGE>   11

                 costs, expenses and charges, plus all prepayment premiums.


          (iv)   Require you at your expense to assemble the Collateral at a
                 location we request in the United States of America.

          (v)    Remove and repossess the Collateral from where it is located,
                 without demand or notice, or make the Collateral inoperable. We
                 have your permission to remove any physical obstructions to
                 removal of the Collateral. We may also disconnect and separate
                 all Collateral from other property. No court order, court
                 hearing or "legal process" will be required for us to repossess
                 the Collateral. You will not be entitled to any damages
                 resulting from removal or repossession of the Collateral. We
                 may use, ship, store, repair or lease any Collateral that we
                 repossess. We may sell any repossessed Collateral at private or
                 public sale. You give us permission to show the Collateral to
                 buyers at your location free of charge during normal business
                 hours. If we do this, we do not have to remove the Collateral
                 from your location. If we repossess the Collateral and sell it,
                 we will give you credit for the net sale price, after
                 subtracting our costs of repossessing and selling the
                 Collateral. If we rent the Collateral to somebody else, we will
                 give you credit for the net rent received, after subtracting
                 our costs of repossessing and renting the Collateral, but the
                 credit will be discounted to present value using a discount
                 rate equal to the Default Rate. The credit will be applied
                 against what you owe us under this Master Agreement, the
                 Schedules, the Notes and any other agreements, loans, leases
                 and other financial arrangements that you have with us. If the
                 credit exceeds the amount you owe under this Master Agreement,
                 the Schedule, the Notes and any other agreements, loans, leases
                 or financial arrangements that you have with us, we will refund
                 the amount of the excess to you.

          (vi)   We will have all of our rights and remedies under this Master
                 Agreement, the Notes, the Schedules and all agreements,
                 instruments and documents executed in connection herewith and
                 therewith and all of our rights and remedies under applicable
                 law, whether as a secured party or otherwise.

          (vii)  Return conditions:

                 (A)  Following a default, at our request you will return the
                      Collateral, freight and insurance prepaid by you, to us at
                      a location we request in the United States of America. It
                      will be returned in good operating condition, as required
                      by Section 5 above. The Collateral will not be subject to
                      any liens when it is returned.

                 (B)  You will pack or crate the Collateral for shipping in the
                      original containers, or comparable ones. You will do this
                      carefully and follow all recommendations of the Supplier
                      and the Manufacturer as to packing or crating.



                                      -11-
<PAGE>   12


                 (C)  You will also return to us the plans, specifications,
                      operating manuals, software, documentation, discs,
                      warranties and other documents furnished by the
                      Manufacturer or Supplier. You will also return to us all
                      service logs and service reports, as well as all written
                      materials that you may have concerning the maintenance and
                      operation of the Collateral.

                 (D)  At our request, you will provide us with up to 60 days
                      free storage of the Collateral at your location, and will
                      let us (or our agent) have access to the Collateral in
                      order to inspect it, display it to others for purchase and
                      sell it.

                 (E)  You will pay us what it costs us to repair the Collateral
                      if you do not return it in the required condition.

          (viii) You will also pay us the following:

                 (A)  All our expenses of enforcing our remedies. This includes
                      all our expenses to repossess, store, ship, repair and
                      sell the Collateral.

                 (B)  Our reasonable attorney's fees and expenses.

                 (C)  Default interest on everything you owe us from the date of
                      your default to the date on which we are paid in full at
                      the Default Rate.

                 (D)  A premium in the amount of five percent (5%) of the
                      outstanding principal balance of the Loan.

          (ix)   You will pay us a late fee whenever you pay any amount that you
                 owe us more than ten (10) days after it is due. You will pay
                 the late fee within one month after the late Payment was
                 originally due. The late fee will be ten (10%) percent of the
                 late Payment. If this exceeds the highest legal amount we can
                 charge you, you will only be required to pay the highest legal
                 amount. The late fee is intended to reimburse us for our
                 collection costs that are caused by late Payment. It is charged
                 in addition to all other amounts you are required to pay us,
                 including Default Interest.

          (x)    You realize that the damages we could suffer as a result of
                 your default are very uncertain. This is why we have agreed
                 with you in advance on the Default Rate to be used in
                 calculating the payments you will owe us if you default. You
                 agree that, for these reasons, the payments you will owe us if
                 you default are "agreed" or "liquidated" damages. You
                 understand that these payments are not "penalties" or
                 "forfeitures."

7.   PERFORMING YOUR OBLIGATIONS IF YOU DO NOT

If you do not perform one or more of your obligations under this Master
Agreement or a Schedule or Note, we may perform it for you. We will notify you
in writing at least ten (10) days



                                      -12-
<PAGE>   13

before we do this. We do not have to perform any of your obligations for you. If
we do choose to perform them, you will pay us all of our expenses to perform the
obligations. You will also reimburse us for any money that we advance to perform
your obligations, together with interest at the Default Rate on that amount.
These will be additional "Payments" that you will owe us and you will pay them
at the same time that your next Payment is due.

8.   INDEMNITY

     (a)  You will indemnify us, defend us and hold us harmless from and against
          any and all claims, expenses and attorney's fees concerning or arising
          from the Collateral, this Master Agreement, any Schedule or Note, or
          your breach of any representation, warranty or covenant. It includes,
          without limitation, any claims, losses or charges concerning, arising
          out of or in connection with the manufacture, selection, delivery,
          possession, use, operation or return of the Collateral and any claims,
          losses or damages concerning, arising out of or in connection with
          this Master Agreement, any Schedule or the Notes.

     (b)  This obligation of yours to indemnify us continues even after the Term
          is over.

9.   MISCELLANEOUS

     (a)  ASSIGNMENT.

          WE MAY ASSIGN OR GRANT A SECURITY INTEREST IN THIS MASTER AGREEMENT,
          ANY SCHEDULE, ANY NOTE OR ANY PAYMENTS WITHOUT YOUR PERMISSION. THE
          PERSON TO WHOM WE ASSIGN IS CALLED THE "ASSIGNEE." THE ASSIGNEE WILL
          NOT HAVE ANY OF OUR OBLIGATIONS UNDER THIS MASTER AGREEMENT. YOU WILL
          NOT BE ABLE TO RAISE ANY DEFENSE, COUNTERCLAIM OR OFFSET AGAINST THE
          ASSIGNEE. NOTWITHSTANDING ANY SUCH ASSIGNMENT OR GRANTING OF A
          SECURITY INTEREST, WE WILL CONTINUE TO BE LIABLE FOR ALL OF OUR
          OBLIGATIONS UNDER THIS MASTER AGREEMENT.

          UNLESS YOU RECEIVE OUR WRITTEN PERMISSION, YOU MAY NOT ASSIGN OR
          TRANSFER YOUR RIGHTS UNDER THIS MASTER AGREEMENT OR ANY SCHEDULE. YOU
          ALSO ARE NOT ALLOWED TO LEASE OR RENT THE COLLATERAL OR LET ANYBODY
          ELSE USE IT UNLESS WE GIVE YOU OUR WRITTEN PERMISSION.

     (b)  ACCEPTANCE BY FINOVA, GOVERNING LAW, JURISDICTION, VENUE, SERVICE OF
          PROCESS, WAIVER OF JURY TRIAL.

          THIS MASTER AGREEMENT WILL ONLY BE BINDING WHEN WE HAVE ACCEPTED IT IN
          WRITING.

          THIS MASTER AGREEMENT IS GOVERNED BY THE SUBSTANTIVE LAWS OF THE STATE
          OF ARIZONA (NOT INCLUDING THE "CHOICE OF LAW" DOCTRINE), THE STATE IN
          WHICH OUR OFFICE IS LOCATED IN WHICH FINAL APPROVAL OF THE TERMS OR
          CONDITIONS OF THIS MASTER AGREEMENT OCCURRED AND FROM WHICH
          DISBURSEMENT OF THE LOAN PROCEEDS WILL BE ORDERED. HOWEVER, IF THIS
          MASTER AGREEMENT IS UNENFORCEABLE UNDER ARIZONA LAW, IT WILL INSTEAD
          BE GOVERNED BY THE LAWS OF THE STATE IN WHICH THE COLLATERAL IS
          LOCATED.

          YOU MAY ONLY SUE US IN A FEDERAL OR STATE COURT THAT IS LOCATED IN
          MARICOPA COUNTY, ARIZONA. THIS APPLIES TO ALL LAWSUITS UNDER ALL LEGAL
          THEORIES, INCLUDING CONTRACT, TORT AND STRICT LIABILITY. YOU CONSENT
          TO THE



                                      -13-
<PAGE>   14

          PERSONAL JURISDICTION OF THESE ARIZONA COURTS. YOU WILL NOT CLAIM THAT
          MARICOPA COUNTY, ARIZONA, IS AN "INCONVENIENT FORUM" OR THAT IT IS NOT
          A PROPER "VENUE."

     WE MAY SUE YOU IN ANY COURT THAT HAS JURISDICTION. WE MAY SERVE YOU WITH
     PROCESS IN A LAWSUIT BY CERTIFIED MAIL, RETURN RECEIPT REQUESTED, TO YOUR
     ADDRESS INDICATED AFTER YOUR SIGNATURE BELOW.

     YOU AND WE EACH WAIVE ANY RIGHT YOU OR WE MAY HAVE TO A JURY TRIAL IN ANY
     LAWSUIT BETWEEN YOU AND US.

     (c)  NOTICES. Your address for notices is your address set forth below your
          name on the signature page of this Master Agreement. We may give you
          written notice in person, by mail, by overnight delivery service, or
          by fax. Mail notice will be effective three (3) days after we deposit
          it with the U.S. Postal Service. Overnight delivery notice requires a
          receipt and tracking number. Fax notice requires a receipt from the
          sending machine showing that it has been sent to your fax number and
          received.

          Our address for notices is our address set forth below our name on the
          signature page of this Master Agreement, with attention: Director,
          Contract Administration. You will also give copies of all notices to
          us at our principal place of business at the address set forth in the
          opening paragraph of this Master Agreement, with attention to Vice
          President, Law Department. You may give us notice the same way that we
          may give you notice.

     (d)  GENERAL

          This Master Agreement benefits our successors and assigns. This Master
          Agreement benefits only those successors and assigns of yours that we
          have approved in writing.

          This Master Agreement binds your successors and assigns. This Master
          Agreement binds only those successors and assigns of ours that clearly
          assume our obligations in writing.

          TIME IS OF THE ESSENCE OF THIS MASTER AGREEMENT

          This Master Agreement, all of the Schedules and the Notes and the
          Commitment Letter are together the entire agreement between you and us
          concerning the Collateral.

          Only an employee of FINOVA who is authorized by corporate resolution
          or policy may modify or amend this Master Agreement or any Schedule or
          Note on our behalf, and this must be in writing. Only he or she may
          give up any of our rights, and this must be in writing. If more than
          one person is the Borrower under this Master Agreement, then each of
          you is jointly and severally liable for your obligations under this
          Master Agreement and all Schedules and Notes.

          This Master Agreement is only for your benefit and for our benefit, as
          well as our successors and assigns. It is not intended to benefit any
          other person.

          If any provision in this Master Agreement is unenforceable, then that
          provision must be deleted. Only unenforceable provisions are to be
          deleted. The rest of this Master Agreement will remain as written.

          We may make press releases and publish a tombstone announcing this
          transaction and its total amount. You may publicize this transaction
          with our prior written consent.




                                      -14-
<PAGE>   15


LENDER:                                  BORROWER:

FINOVA CAPITAL CORPORATION               AVIRON, INC.
10 WATERSIDE DRIVE                       297 N. BERNARDO AVENUE
FARMINGTON, CT  06032-3065               MOUNTAIN VIEW, CA 94043


BY: /s/ Linda A. Moschitto               BY: /s/ Fred Kurland
   -----------------------------            ----------------------------
PRINTED NAME: Linda A. Moschitto         PRINTED NAME: Fred Kurland
             -------------------                      ------------------
TITLE: Director-Contract Administration  TITLE: Senior Vice President and CFO
      --------------------------               -------------------------
FAX NUMBER: (860) 676-1814               Taxpayer ID#77-0309686
                                                     -------------------
DATE ACCEPTED: July 23, 1999             FAX NUMBER: 650-919-6612
              ------------------                    --------------------
                                         DATED:  June 22, 1999
                                               -------------------------





























                                      -15-
<PAGE>   16




STATE OF CALIFORNIA

COUNTY OF SANTA CLARA



     I acknowledge that Fred Kurland, who stated that he is Senior Vice
President & CFO of the Borrower named above, signed this Master Loan and
Security Agreement in my presence today: June 22, 1999. He/She acknowledged to
me that his/her signature on this Master Loan and Security Agreement was
authorized by a valid resolution or other valid authorization from Borrower's
board of directors or other governing body.



                                        /s/ Anne M. LeDoux
                                        ---------------------------
                                        Notary Public





[SEAL]

















                                      -16-