Exhibit 2.1

SUBSCRIPTION FOR SHARES

(Alnylam Pharmaceuticals, Inc.)

TO:             Tekmira Pharmaceuticals Corporation (the Corporation)

DATED:     March 28, 2008

The undersigned (the Subscriber) hereby irrevocably subscribes for and agrees to purchase 2,083,333 common shares of the Corporation (the Shares) at the subscription
price of US$2.40 per Share (the Subscription Price), upon and subject to the terms and conditions set forth in Terms and Conditions of Subscription for Shares of Tekmira Pharmaceuticals Corporation attached hereto
(together with the face pages and the attached Schedules, the Subscription Agreement).

The Shares are listed on the
Toronto Stock Exchange (the Exchange) and as a result the Corporation is subject to the rules and policies of the Exchange. The Corporation is also a reporting issuer (or equivalent) under the securities laws of all of
the provinces of Canada.

SUBSCRIPTION AND SUBSCRIBER INFORMATION

Please print all information (other than signatures), as applicable, in the space provided below.

|                                                                                                               |  |                                       |  |                                                                |  |                                                                                                                                                                                 
|-------------------------------------------------------------------------------------------------------------- |  | ------------------------------------- |  | -------------------------------------------------------------- |  | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Alnylam
Pharmaceuticals, Inc.                                                                                  |  |                                       |  | Number of Shares: 2,083,333                                   
|(Name of Subscriber)                                                                                           |  |                                       |  |                                                               
|                                                                                                               |  |                                      
|Account Reference (if applicable):                                                                             |  |                                       |  | Aggregate Subscription Amount:                                
|                                                                                                               |  |                                       |  |                                                                |  | US$4,999,999.20                                                                                                                                                                 
|                                                                                                               |  |                                       |  |                                                                |  | (the
Aggregate Subscription Amount)                                                                                                                                           
|By:                                                                                                            |  | /S/ BARRY GREENE
Authorized Signature |  |                                                                |  | If the Subscriber is signing as agent for a principal (beneficial purchaser) and is not purchasing as trustee or agent for accounts fully managed by it, complete the
following:
|President and Chief Operating Officer                                                                          |  |                                       |  |                                                               
|(Official Capacity or Title  if the Subscriber is not an individual)                                          |  |                                       |  | (Name of Principal)                                           
|                                                                                                               |  |                                       |  |                                                                |  |                                                                                                                                                                                 
|Barry Greene                                                                                                   |  |                                       |  | (Principals Address)                                         
|(Name of individual whose signature appears above if different than the name of the subscriber printed above.) |  |                                       |  |                                                               
|300 Third Street                                                                                               |  |                                       |  |                                                               
|(Subscribers Address, including Province/State)                                                               |  |                                       |  | (Telephone Number)                          
  (Email Address)
|Cambridge, MA
02142                                                                                            |  |                                       |  |                                                               
|617-551-8200                                                                                                   |  |                                       |  |                                                               
|(Telephone Number)                      
                      (Email Address)                                 |  |                                       |  |                                                               
|Account Registration Information:                                                                              |  |                                       |  | Delivery Instructions as set forth below:                     
|Alnylam Pharmaceuticals, Inc.                                                                                  |  |                                       |  | x Same as registered address, or                              
|(Name)                                                                                                         |  |                                       |  |                                                               
|                                                                                                               |  |                                       |  | (Name)                                                        
|(Account Reference, if applicable)                                                                             |  |                                       |  |                                                               
|300 Third Street, Cambridge, MA 02142                                                                          |  |                                       |  | (Account Reference, if applicable)                            
|(Address, including Postal/Zip Code)                                                                           |  |                                       |  |                                                               
|                                                                                                               |  |                                       |  |                                                               
|Number and kind of Shares of the Corporation held, if any:                                                     |  |                                       |  | (Address)                                                     
|                                                                                                               |  |                                       |  |                                                               
|                                                                                                               |  |                                       |  | (Contact Name)                          
  (Telephone Number) 
|                                                                                                               |  |                                       |  |                                                               



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TERMS AND CONDITIONS OF SUBSCRIPTION FOR

SHARES OF TEKMIRA PHARMACEUTICALS CORPORATION

Terms of the Offering

1. The Subscriber acknowledges (on its own behalf and, if
applicable, on behalf of each Person on whose behalf the Subscriber is contracting) that this subscription is subject to acceptance or rejection by the Corporation in whole or in part. Acceptance of this subscription shall be effective upon the
delivery of a facsimile copy or electronic copy of this Subscription Agreement, duly executed by the Corporation, to the Subscriber. The Corporation shall, by its acceptance of this subscription, be bound by the terms and conditions hereof. The
parties agree that this Subscription and all money tendered herewith will be returned to the Subscriber, without interest or deduction, if this Subscription is not accepted by the Corporation.

2. The Subscriber acknowledges (on its own behalf and, if applicable, on behalf of each Person on whose behalf the Subscriber is contracting) that this
offering of Shares (the Offering) will not in any way restrict the Corporation from issuing additional Shares of the Corporation at prices, on terms and in amounts as may be determined by the Corporation, in its sole and absolute
discretion, subject to the pre-emptive rights of the Subscriber as set forth in Section 9(f) below.

3. This Agreement and the
parties obligations hereunder shall terminate upon the earlier of (i) June 30, 2008 and (ii) the termination of the share purchase agreement in connection with the Business Combination (Termination Date) and
the Corporation acknowledges that any obligations of the Subscriber pursuant this Subscription Agreement shall be null and void on and after such Termination Date.

Definitions



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|-- |  | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|4. |  | (a) Applicable Securities Laws means, collectively, the securities legislation having application in each of the
Reporting Jurisdictions and the respective regulations and rules under such legislation and the instruments, policies, rulings, orders, codes, notices and interpretation notes of the applicable Regulatory Authorities having
application;

(b) Business Combination has the meaning set forth in Section 12(b);

(c) Closing Date means such date for closing of the Offering as agreed to by the Corporation and the Subscriber;

(d) Closing Time means 8:00 a.m. Vancouver time on the Closing Date, or such other time as agreed to by the
Corporation and the Subscriber;

(e) Exchange means the Toronto Stock Exchange;

(f) Disclosure Documents means the documents filed by the Corporation, and from December 30, 2005 until April 30,
2007, by 1322256 Alberta Ltd. (formerly Inex Pharmaceuticals Corporation), under their respective profiles at www.sedar.com;

(g) Material Adverse Effect means, any effect in or on the business, operations, results of operations, assets, liabilities, obligations (whether absolute, accrued, conditional, contingent or
otherwise), or condition (financial or otherwise) of a Person (on a consolidated basis) which is material and adverse to such Person (on a consolidated basis) other than a change, effect, event or occurrence relating to (i) general political,
economic or financial conditions, including in Canada and the United States or internationally, (ii) the state of Canadian, United States or international credit, securities or currency exchange markets in general, including any reduction in
market indices, (iii) factors affecting the industries in which such Person operates in general, (iv) changes in Laws or interpretations thereof by any Governmental Entity, (v)



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any failure, in and of itself, by a Person to meet any of its published estimates of revenues for any period ending on or after the date of this Agreement and before the Closing Date,
(vi) the announcement of the transactions contemplated by the Tekmira-Protiva Share Purchase Agreement or other communication by Tekmira of its plans or intentions with respect to its business or that of Protivas following the closing of
the Business Combination, (vii) the consummation of the transactions contemplated by the Tekmira-Protiva Share Purchase Agreement or any actions taken pursuant to the Tekmira-Protiva Share Purchase Agreement, (viii) any delay or disruption
to the ordinary course of a Persons business occasioned by the announcement or implementation of the transactions contemplated by the Tekmira-Protiva Share Purchase Agreement, (ix) any natural disaster or any acts of terrorism, sabotage,
military action or war (whether or not declared) or any escalation or worsening thereof; (x) any change in the market price or trading volume of the Tekmira Shares, (xi) any suspension, rejection, refusal of or request to re-file any
regulatory application or filing, (xii) any negative actions, requests, recommendations or decisions of the United States Food and Drug Administration (the FDA), Health Canada or similar Governmental Entity which would
materially and adversely cause a delay in the development of a product candidate, (xiii) any change, effect, event or occurrence relating to a Persons clinical trials or studies, (xiv) any change, effect, event or occurrence relating
to the products, product candidates, clinical trials or studies of any other Person, (xv) safety findings with respect to a therapeutic agent, (xvi) changes in generally accepted accounting principles or regulatory accounting requirements,
(xvii) any action taken by any Person or any of its subsidiaries to which the other party hereto has consented to in writing; (xviii) any matter, either alone or in combination with other matters, that has been previously disclosed, or
(xix) any disputes or litigation with respect to any intellectual property rights;

(h) Person means an
individual, a firm, a corporation, a syndicate, a partnership, a trust, an association, an unincorporated organization, a joint venture, an investment club, a government or an agency or political subdivision thereof and every other form of legal or
business entity of whatsoever nature or kind;

(i) Regulatory Authorities means the securities commission or
similar regulatory authority in each of the Reporting Jurisdictions;

(j) Reporting Jurisdictions means all of the
provinces of Canada;

(k) Securities Laws means the securities legislation and the regulations and rules under such
legislation, and the instruments, policies, rulings, orders, codes, notices and interpretation notes of the applicable securities commission or similar regulatory authority of the applicable jurisdiction;

(l) subsidiary has the meaning ascribed to it in the Business Corporations Act (British Columbia), and for the purposes
of any certificate delivered with respect to the closing condition in section 12(i) hereto and when used in any representations and warranties of the Corporation made as at the Closing Time, includes Protiva Biotherapeutics Inc.
(Protiva); and

(m) Tekmira-Protiva Share Purchase Agreement means the share purchase agreement
by and among Protiva, Protivas securityholders and the Corporation dated March 28, 2008.

Representations and Warranties of the
Corporation

5. The Corporation hereby represents and warrants to the Subscriber (and acknowledges that the Subscriber is relying thereon)
that, as at the date of acceptance of this subscription and at the Closing Time:

(a) each of the Corporation and its
subsidiaries is a valid and subsisting corporation duly incorporated and in good standing under the laws of the jurisdiction in which it was incorporated, continued or amalgamated and has all the requisite corporate power and authority to enter into
this Subscription Agreement and to carry out its obligations hereunder;



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(b) there are no shareholders agreements governing the affairs of the Corporation or
any of its subsidiaries or relationship, rights and duties of its shareholders nor are there any voting trusts, pooling arrangements or similar agreements with respect to the ownership or voting of any equity in trust in the Corporation;

(c) [Intentionally deleted]

(d) the authorized capital of the Corporation consists of an unlimited number of common shares without par value and an unlimited number of preferred shares without par value, of which as at the date
hereof, 24,565,681 common shares and no preferred shares are issued and outstanding as fully paid and non-assessable, and the Shares to be issued under this Subscription Agreement will at the time of issue, be validly issued and outstanding as fully
paid and non-assessable;

(e) all of the material transactions of the Corporation have been promptly and properly recorded or
filed in or with the books or records of the Corporation and the minute books of the Corporation contain all records of the meetings and proceedings of the Corporations directors, shareholders and other committees, if any, since its
incorporation;

(f) each of the Corporation and its subsidiaries has the corporate power and capacity to own the assets owned
by it and to carry on the business carried on by it and is duly qualified to carry on its business under the laws of each jurisdiction in which it carries on business or holds property to the extent required by such laws;

(g) each of the Corporation and its subsidiaries has good and marketable title to its assets free and clear of all mortgages, liens,
charges, pledges, security interests, encumbrances, claims or demands of any kind whatsoever, except for equipment leases;

(h)
to the best of the Corporations knowledge, each of the Corporation and its subsidiaries owns, possesses or licenses all patents, patent rights, inventions, copyrights, know-how (including trade secrets and other unpatented and/or unpatentable
proprietary or confidential information, systems or procedures), trademarks, service marks and trade names (the Intellectual Property) necessary to carry on the business now operated by it, except where the failure to own,
possess, license or otherwise be able to use or acquire the Intellectual Property would not, singly or in the aggregate, have a Material Adverse Effect on the Corporation and its subsidiaries, taken as a whole;

(i) neither the Corporation nor its subsidiaries has received any notice of infringement of or conflict with asserted rights of others
with respect to any of its Intellectual Property which, singly or in the aggregate, if the subject of an unfavourable decision, ruling or finding, would have a Material Adverse Effect on the Corporation;

(j) each of the Corporation and its subsidiaries now holds, and as of the Closing Date will hold, all licenses, certificates, approvals
and permits from all state, United States, foreign and other regulatory authorities, including but not limited to the FDA and any foreign regulatory authorities performing functions similar to those performed by the FDA, that are material to the
conduct of its business (as such business is currently conducted), except for such licenses, certificates, approvals and permits the failure of which to hold would not have a Material Adverse Effect on the Corporation and its subsidiaries, taken as
a whole, all of which are valid and in full force and effect (and there is no proceeding pending or, to the knowledge of the Corporation, threatened which may cause any such license, certificate, approval or permit to be withdrawn, cancelled,
suspended or not renewed). Neither the Corporation nor its subsidiaries is in violation of any law, order, rule, regulation, writ, injunction or decree of any court or governmental agency or body, applicable to the investigation of new drugs in
humans and animals, including, but not limited to, those promulgated by the FDA, the violation of which would have a Material Adverse Effect on the Corporation and its subsidiaries, taken as a whole. All of the descriptions in the Disclosure
Documents Incorporated of the legal and governmental proceedings by or before the FDA or any foreign, state or local government body exercising comparable authority are accurate, complete and fair;



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(k) the clinical studies and tests (including, but without limitation, the human and animal
clinical trials) that were conducted by and are being conducted by the Corporation or in which the Corporation has directly participated and is participating, which are described in the Disclosure Documents or the results of which are referred to in
the Disclosure Documents, and, to the best of the Corporations knowledge, such studies and test that were conducted on behalf of the Corporation, were and, if still pending, are being conducted in all material respects (i) in accordance
with the protocols, procedures and controls for such studies and tests of new medical devices or biologic products, as the case may be, and (ii) in accordance with all applicable laws, rules and regulations; the descriptions of the results of
such studies and tests contained in the Disclosure Documents are accurate, complete and fair, and the Corporation has no knowledge of any other studies or tests, the results of which call into question the results described or referred to in the
Disclosure Documents, and the Corporation has not received any notices or correspondence from the FDA or any other governmental agency requiring the termination, suspension or modification of any studies or tests conducted by, or on behalf of, the
Corporation or in which the Corporation has participated that are described in the Disclosure Documents or the results of which are referred to in the Disclosure Documents that would result in an untrue statement in the Disclosure Documents or
require a fact to be stated in order to make a statement in the Disclosure Documents not misleading in light of the circumstances in which it was made or otherwise necessitate a change to the descriptions in the Disclosure Documents;

(l)(i) each of the Corporation and its subsidiaries (x) has conducted and are conducting its business in compliance in all material
respects with all applicable laws, rules and regulations of each jurisdiction in which its business is carried on including, without limitation, all applicable licensing and waste management legislation, regulations or by-laws, occupational health
and safety laws, environmental protection legislation, regulations or by-laws or similar legislation, regulations or by-laws (including ambient air, surface water, groundwater, land surface or subsurface strata) or wildlife, including laws relating
to the release or threatened release of chemicals, pollutants, contaminants, wastes, toxic substances, hazardous substances, petroleum or petroleum products (collectively, Hazardous Materials) or to the manufacture, processing,
distribution, use, treatment, storage, disposal, transport or handling of Hazardous Materials (collectively, Environmental Laws); (y) holds all necessary licences, permits, approvals, consents, certificates, registrations and
authorizations, whether governmental, regulatory or otherwise under any applicable Environmental Law, to enable its business to be carried on as now conducted and its property and assets to be owned, leased and operated, and the same are validly
existing and in good standing, except to the extent that non-compliance with any such laws, rules or regulations, or failure to hold any such licences, permits, or similar approvals would not have a Material Adverse Effect on the Corporation and its
subsidiaries, taken as a whole; (ii) there are no pending or, to the knowledge of the Corporation, threatened administrative, regulatory or judicial actions, suits, demands, demand letters, claims, liens, notices of non-compliance or violation,
investigation or proceedings relating to any Environmental Laws against the Corporation and its subsidiaries and (iii) there are no events or circumstances that would reasonably be expected to form the basis of an order for clean-up or
remediation, or an action, suit or proceeding by any private party or governmental body or agency, against or affecting the Corporation and its subsidiaries relating to Hazardous Materials or any Environmental Laws;

(m) the Corporation is not aware of any legislation or expected changes, amendments or repeal of any legislation which it anticipates will
have a Material Adverse Effect on the Corporation or its subsidiaries, taken as a whole;

(n) there is no action, proceeding or
investigation, whether or not purportedly on behalf of the Corporation or any of its subsidiaries, pending or, to the knowledge of the Corporation or its directors and officers, threatened against or affecting the Corporation, at law or in equity or
before or by any federal, provincial, municipal or other governmental department, commission, board or agency, domestic or foreign, which could in any way result in a Material Adverse Effect on the Corporation or which questions the validity of the
issuance of the Shares or of any action taken or to be taken by the Corporation pursuant to or in connection with this Subscription Agreement;

(o) CIBC Mellon Trust Company, at its principal offices in the cities of Vancouver and Toronto has been duly appointed transfer agent and registrar for the common shares of the Corporation;



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(p) neither the Corporation nor its subsidiaries, in a manner that would be materially
adverse to the Corporation or its subsidiaries, is in violation of its constating documents or in default in the performance or observance of any material obligation, agreement, covenant or condition contained in any contract, indenture, trust,
deed, mortgage, loan agreement, note, lease or other agreement or instrument to which it is a party or by which it or its property may be bound;

(q) the Corporation has filed all documents required to be filed with the Regulatory Authorities and the Exchange and such documents have been filed within the times prescribed; the Disclosure Documents
contain no untrue statement of a material fact (as defined under Applicable Securities Laws) as at the date thereof nor do they omit to state a material fact which, at the date thereof, was required to have been stated or was necessary to prevent a
statement that was made from being false or misleading in the circumstances in which it was made and were prepared in accordance with and complied with Applicable Securities Laws;

(r) the Corporation is, and at the Closing Time, will be a reporting issuer (or equivalent) in all of the provinces of Canada, and the
Corporation is not, and at the Closing Time will not be, in default of any of the requirements of the Applicable Securities Laws;

(s) the common shares of the Corporation are, and at the Closing Time will be, listed and posted for trading on the Exchange and the Corporation is not, and at the Closing Time will not be, in default of
any of the listing requirements of the Exchange;

(t) none of the holders of common shares of the Corporation or the directors
or officers of the Corporation or any associate or affiliate of any of the foregoing had, has or to the knowledge of the Corporation intends to have, any material interest, direct or indirect, in any material transaction including the Business
Combination, or any proposed material transaction with the Corporation which, as the case may be, materially affects, is material to or will materially affect the Corporation, except as disclosed in the Disclosure Documents and except for
Dr. Pieter Cullis, who holds approximately 70,000 shares of Protiva;

(u) except as set forth in the subscription
agreement proposed to be made by Roche Finance Ltd. (Roche) and as set forth herein, no person, firm or corporation has any agreement, option, right or privilege, whether pre-emptive, contractual or otherwise, capable of becoming
an agreement for the purchase, acquisition, subscription for or issuance of any of the unissued shares or other securities of the Corporation, other than rights issued under the Corporations share incentive plans or pursuant to the Business
Combination;

(v) neither the Corporation nor any of its subsidiaries, as applicable, is in default in the performance or in
breach of any of their obligations pursuant to any existing contract, document or agreement between the Corporation or any of its subsidiaries and the Subscriber, no representation or warranty of the Corporation or any of its subsidiaries set forth
in any of such contracts, documents or agreements was untrue in any respect when made, and neither the Corporation nor any of its subsidiaries, as applicable, has committed any fraud or material misstatement or omission of fact that is required to
be stated or disclosed pursuant to such contracts, documents or agreements;

(w) [Reserved]

(x) the audited financial statements of the Corporation for its fiscal years ended December 31, 2006 and 2005, the unaudited
financial statements of the Corporation for the interim nine month period ended September 30, 2007, and any other financial statements to be filed by the Corporation on www.sedar.com including the notes thereto, (collectively the
Financial Statements) are and will be true and correct in every material respect and present fairly and accurately the financial position and results of the operations of the Corporation for the periods then ended and the
Financial Statements have been prepared in accordance with Canadian generally accepted accounting principles applied on a consistent basis;

(y) except as described in the Financial Statements, there are no material liabilities of the Corporation, whether direct, indirect, absolute, contingent or otherwise;



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(z) since December 31, 2006, no material change (as defined under Applicable Securities
Laws) (actual, anticipated, proposed or prospective, whether financial or otherwise) in the business, prospects, financial condition or results of operations of the Corporation or the right or capacity of the Corporation to carry on its business or
the capital of the Corporation has occurred with respect to which the requisite material change report has not been filed and no such report has been filed on a confidential basis;

(aa) each of the Corporation and its subsidiaries has duly and on a timely basis filed all tax returns required to be filed by it, has
paid all taxes due and payable by it and have paid all assessments and re-assessments and all other taxes, governmental charges, penalties, interest and other fines due and payable by it and which are claimed by any governmental authority to be due
and owing, and adequate provision has been made for taxes payable for any completed fiscal period for which tax returns are not yet required to be filed;

(bb) there are no agreements, waivers or other arrangements providing for an extension of time with respect to the filing of any tax return or payment of any tax, governmental charge or deficiency by the
Corporation or any of its subsidiaries; there are no actions, suits or proceedings threatened or pending against the Corporation or any of its subsidiaries in respect of taxes, governmental charges or assessments and there are no matters under
discussion with any governmental authority relating to taxes, governmental charges or assessments asserted by any such authority;

(cc) the Corporation is not an investment company under the U.S. Investment Company Act of 1940, as amended, and, for as long as the Subscriber owns any shares purchased under this
Subscription Agreement, the Corporation shall take all actions necessary to ensure that it not an investment company under the U.S. Investment Company Act of 1940, as amended;

(dd) the execution and delivery of this Subscription Agreement, the fulfilment of the terms hereof by the Corporation, and the issuance,
sale and delivery of the Shares at the Closing Time:

(i) do not require the consent, approval, authorization, registration or
qualification of or with any governmental authority, stock exchange, Regulatory Authority or other third party, except:

(A)
such as have been obtained or will be obtained prior to the Closing Time; and

(B) such as may be required (and will be
obtained as provided herein) under Applicable Securities Laws; and

(ii) do not and will not result in a breach of or default
under, and do not and will not create a state of facts which, after notice or lapse of time or both, will result in a breach of or default under, and do not and will not conflict with:

(A) any of the terms, conditions or provisions of the articles or notice of articles of the Corporation, or resolutions of the
shareholders, directors, or any committee of directors of the Corporation, respectively, or any material indenture, agreement or instrument to which the Corporation is a party or by which either of them is contractually bound; or

(B) any laws of Canada or the Province of British Columbia or any judgment, order or decree of any governmental body, agency or court
having jurisdiction over the Corporation;

(iii) have been duly authorized by all necessary corporate action on the part of the
Corporation and upon such execution and delivery of this Subscription Agreement by the Corporation this Subscription Agreement shall constitute a valid and binding obligation of the Corporation enforceable against the Corporation in accordance with
its terms except as enforcement thereof may be limited by bankruptcy, insolvency, reorganization, moratorium and



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other laws relating to or affecting the rights of creditors generally and except as limited by the application of equitable principles when equitable remedies are sought, and by the fact that
rights to indemnity, contribution and waiver, and the ability to sever unenforceable terms, may be limited by applicable law;

(ee) there is no person, firm or corporation acting or purporting to act for the Corporation entitled to any brokerage or finders
fee in connection with this Subscription Agreement or any of the transactions contemplated hereunder;

(ff) all Shares to be
issued under this Subscription Agreement have been or before the Closing Time will be duly authorized for issuance and, when certificates for such securities are countersigned by the Corporations transfer agent and registrar and issued,
delivered and paid for, will be validly issued, fully paid and non-assessable common shares of the Corporation registered in the names of the holders thereof, free and clear of all voting restrictions, trade restrictions (except as may be imposed by
operation of Applicable Securities Laws), liens, charges or encumbrances of any kind whatsoever, and all statements made in the Disclosure Documents describing such securities are and, at the respective times of filing thereof, will be accurate;

(gg) the definitive form of certificate for the common shares of the Corporation is in proper form under the laws of British
Columbia and complies with the requirements of the Exchange and the articles of the Corporation;

(hh) no Regulatory Authority
has issued any order preventing or suspending trading in any securities of the Corporation or prohibiting the issue and sale of the Shares, no such proceedings for such purpose are pending or, to the knowledge of the Corporation, threatened;

(ii) no representation and warranty or other statement made by the Corporation in this Subscription Agreement contains any
untrue statement or omits to state a material fact that is required to be stated or that is necessary to make any statement not misleading in light of the circumstances in which it was made; and

(jj) as at the date of acceptance of this subscription, the representations and warranties made by Protiva in the Tekmira-Protiva Share
Purchase Agreement are true and correct and, as at the Closing Time, the representations and warranties made by Protiva in the Tekmira-Protiva Share Purchase Agreement are true and correct (in both cases, as if such representations and warranties
were given by the Corporation herein) except as affected by transactions, changes, conditions, events or circumstances contemplated or permitted by the Tekmira-Protiva Share Purchase Agreement, in both cases without any amendment, supplement,
modification, waiver or consent by any party to the Tekmira-Protiva Share Purchase Agreement of any provision of the Tekmira-Protiva Share Purchase Agreement, except as may be consented to by the Subscriber, acting reasonably and without undue
delay, and the Tekmira-Protiva Share Purchase Agreement is in full force and effect and has not been amended, supplemented or modified in any manner or way whatsoever and no provision, exhibit or schedule thereof has been waived or any breach
thereof consented to, except as may be consented to by the Subscriber, acting reasonably and without undue delay.

Acknowledgements,
Representations, Warranties and Covenants of the Subscriber

6. [Reserved]

7. The Subscriber acknowledges that the Offering, of which this Subscription Agreement forms a part, is not subject to a minimum subscription level and as such, upon acceptance by the Corporation in
accordance with the terms and conditions of this Subscription Agreement, subscription funds will be immediately available for use by the Corporation. The Subscriber further acknowledges that the Corporation may complete additional financings in the
future which may have a dilutive effect on existing shareholders at such time, including a Subscriber hereunder.



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8. The Subscriber acknowledges, represents, warrants and covenants to the Corporation that:

(a) it has been independently advised as to the restrictions with respect to trading in the Shares imposed by applicable securities
regulatory legislation, confirms that no representation has been made to it by or on behalf of the Corporation with respect thereto, acknowledges that it is aware of the characteristics of the Shares, the risks relating to an investment therein and
of the fact that it may not be able to resell the Shares except in accordance with limited exemptions under applicable securities legislation and regulatory policy until expiry of the applicable restriction period and compliance with the other
requirements of applicable law, and it agrees that any certificates representing the Shares may bear the following legends:

UNLESS PERMITTED UNDER SECURITIES LEGISLATION, THE HOLDER OF THESE SECURITIES MUST NOT TRADE THE SECURITIES BEFORE <INSERT
DATE THAT IS FOUR (4) MONTHS AND ONE (1) DAY AFTER CLOSING DATE>.

THE SECURITIES REPRESENTED BY THIS
CERTIFICATE ARE LISTED ON THE TORONTO STOCK EXCHANGE; HOWEVER, THE SAID SECURITIES CANNOT BE TRADED THROUGH THE FACILITIES OF SUCH EXCHANGE SINCE THEY ARE NOT FREELY TRANSFERABLE, AND CONSEQUENTLY ANY CERTIFICATE REPRESENTING SUCH SECURITIES IS NOT
GOOD DELIVERY IN SETTLEMENT OF TRANSACTIONS ON THE TORONTO STOCK EXCHANGE.

(b) it has not received or
been provided with, nor has it requested, nor does it have any need to receive, any prospectus or offering memorandum, or any other document (other than financial statements, interim financial statements or any other document, the content of which
is prescribed by statute or regulation) describing the business and affairs of the Corporation which has been prepared for delivery to, and review by, prospective purchasers in order to assist it in making an investment decision in respect of the
Shares;

(c) it has not become aware of any advertisement in printed media of general and regular paid circulation (or other
printed public media), radio, television or telecommunications or other form of advertisement (including electronic display) with respect to the distribution of the Shares;

(d) it has relied solely upon information publicly available on SEDAR relating to the Corporation and the representations and warranties contained within this Subscription Agreement and other existing and
proposed agreements by and among the Subscriber, the Corporation, Alnylam and Protiva, and not upon any verbal or other written representation as to fact or otherwise made by or on behalf of the Corporation;

(e) it acknowledges that:

(i) it is not resident in British Columbia;

(ii) no securities commission or
similar regulatory authority has reviewed or passed on the merits of the Shares;

(iii) there is no government or other
insurance covering the Shares;

(iv) there are risks associated with the purchase of the Shares;

(v) there are restrictions on the Subscribers ability to resell the Shares and it is the responsibility of the Subscriber to find
out what those restrictions are and to comply with them before selling any of the Shares; and



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(vi) the Corporation has advised the Subscriber that the Corporation is relying on an
exemption from the requirements to provide the Subscriber with a prospectus and to sell the Shares through a Person registered to sell securities under the Securities Act (British Columbia) and, as a consequence of acquiring the Shares
pursuant to this exemption, certain protections, rights and remedies provided by the Securities Act (British Columbia), including statutory rights of rescission or damages, will not be available to the Subscriber;

(f) it is aware that none of the Shares have been nor will be registered under the United States Securities Act of 1933, as amended
(U.S. Securities Act) and that these Shares may not be offered or sold in the United States without registration under the U.S. Securities Act or compliance with requirements of an exemption from registration;

(g) if the Subscriber is a resident of the United States or is a U.S. Person (as defined in Regulation S promulgated under the U.S.
Securities Act), the Subscriber has concurrently executed and delivered a certificate in the form attached as Schedule A hereto;

(h) it undertakes and agrees that it will not offer, sell or otherwise dispose of any of the Shares in the United States unless the
Corporation has consented to such offer, disposition or sale and such Shares are registered under the U.S. Securities Act and the securities laws of all applicable states of the United States or an exemption from such registration requirements is
available, and further that it will not resell any of the Shares in any jurisdiction, except in accordance with the provisions of applicable securities legislation, regulations, rules, policies and orders and stock exchange rules;

(i) the Subscriber is duly incorporated and is validly subsisting under the laws of its jurisdiction of incorporation and has all
requisite legal and corporate power and authority to execute and deliver this Subscription Agreement, to subscribe for the Shares as contemplated herein and to carry out and perform its obligations under the terms of this Subscription Agreement;

(j) this Subscription Agreement has been duly and validly authorized, executed and delivered by and constitutes a legal,
valid, binding and enforceable obligation of the Subscriber;

(k) it acknowledges that no representation has been made to it:

(i) as to the future value or price of the Shares;

(ii) that any Person will resell or repurchase the Shares; or;

(iii) that any
Person will refund the purchase price of the Shares;

(l) it has such knowledge in financial and business affairs as to be
capable of evaluating the merits and risks of its investment and it is able to bear the economic risk of loss of its investment;

(m) it understands that the Shares are being offered for sale only on a private placement basis and that the sale and delivery
of the Shares is conditional upon such sale being exempt from the requirements as to the filing of a prospectus or the preparation of an offering memorandum in prescribed form or upon the issuance of such orders, consents or approvals as may be
required to permit such sale without the requirement of filing a prospectus or delivering an offering memorandum in prescribed form and that certain protections, rights and remedies provided by applicable securities legislation, in connection with
the filing of a prospectus may not be available to the Subscriber;

(n) if required by applicable securities legislation,
regulations, rules, policies or orders or by any securities commission, stock exchange, other regulatory authority or the Corporation, the Subscriber will execute, deliver, file and otherwise assist the Corporation in filing, such reports,
undertakings and other documents with respect to the issue of the Shares as may be required;



- 10 -



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(o) the entering into of this Subscription Agreement and the transactions contemplated
hereby will not result in a violation of any of the terms or provisions of any law applicable to the Subscriber, or any of the Subscribers constating documents, or any agreement to which the Subscriber is a party or by which it is bound;

(p) the Subscriber acknowledges that it has obtained independent legal advice with respect to its subscription for Shares and
accordingly, has been independently advised as to the meanings of all terms contained herein relevant to the Subscriber for the purposes of giving representations, warranties and covenants under this Subscription Agreement;

(q) the information provided by the Subscriber under the heading Subscription and Subscriber Information is true and correct
in all material respects and will be true and correct as of the Closing Date;

(r) it does not act jointly or in concert with
any other Subscriber under the Offering for the purposes of the acquisition of the Shares;

(s) it will not resell the Shares,
except in accordance with the provisions of Applicable Securities Laws and Exchange rules, if applicable, in the future;

(t)
the delivery of this Subscription Agreement, the acceptance hereof by the Corporation and the issuance of the Shares to the Subscriber complies with all applicable laws of the Subscribers jurisdiction of residence and domicile and will not
cause the Corporation or any of its officers or directors to become subject to or require any disclosure, prospectus or other reporting requirement;

(u) the Corporation may complete additional financings in the future in order to develop the business of the Corporation and to fund its ongoing development; that there is no assurance that such
financings will be available and, if available, on reasonable terms; any such future financings may have a dilutive effect on current securityholders, including the Subscriber; that if such future financings are not available, the Corporation may be
unable to fund its ongoing development and the lack of capital resources may result in the failure of its business venture;

(v) there is no Person acting or purporting to act on behalf of the Subscriber in connection with the transactions contemplated herein who
is entitled to any brokerage or finders fee. If any such Person establishes a claim that any fee or other compensation is payable in connection with this subscription for the Shares, the Subscriber covenants to indemnify and hold harmless the
Corporation with respect thereto and with respect to all costs reasonably incurred in the defence thereof.

Covenants of the Corporation

9. The Corporation hereby covenants and agrees with the Subscriber, which covenants and agreements shall survive the Closing Time for the
benefit of the Subscriber, as follows:

(a) the Corporation will maintain its status as a reporting issuer (or
equivalent) in, and not in default of any requirement of the Applicable Securities Laws for a period of at least 48 months after the Closing Date, unless the common shares of the Corporation held by the Subscriber are sold, transferred or otherwise
disposed of in a transaction that results in the Corporation ceasing to be a reporting issuer (or equivalent);

(b)
the Corporation, or its successor, will remain a valid and subsisting corporation duly incorporated and in good standing under the laws of the jurisdiction in which it was incorporated, continued or amalgamated for a period of at least 48 months
after the Closing Date, unless the common shares of the Corporation held by the Subscriber are sold, transferred or otherwise disposed of in a transaction that results in the Corporation ceasing to be a valid and subsisting corporation;

(c) the Corporation will maintain the listing of the common shares of the Corporation on the Exchange or an alternative North American
stock exchange or automated quotation system for a period of



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at least 48 months after the Closing Date, unless the common shares of the Corporation held by the Subscriber are sold, transferred or otherwise disposed of in a transaction that results in the
Corporations common shares no longer being listed;

(d) forthwith after the Closing, the Corporation will file such forms
and documents as may be required under the Applicable Securities Laws of the Province of British Columbia relating to the Offering;

(e) the Corporation will perform and carry out all of the acts and things to be completed by it as provided in this Subscription Agreement; and

(f) during the 48 month period following the Closing Date, and provided the Subscriber holds at least 2% of the common shares of the
Corporation on a non-diluted basis, the Corporation will not issue any securities (including any common shares or any debt or other securities of any kind convertible into common shares) of any type or class to any person (the Proposed
Recipient) unless the Corporation has offered to the Subscriber in accordance with the provisions of this Section (f), the right to purchase the Subscribers Pro Rata Share of such issuance (Pre-emptive Rights) for
a per security consideration, payable solely in cash, equal to the per security consideration to be paid by the Proposed Recipient and otherwise on the same terms and conditions as are offered to the Proposed Recipient. The Corporation shall not be
obligated to offer to the Subscriber any portion of such issuance above the Subscribers Pro Rata Share. The Subscriber shall not be obliged to purchase any securities offered pursuant to this Section (f). The restrictions under this Section
(f) shall not apply to (a) any issuance of securities in connection with any share split, share dividend or other similar event; (b) any issuance of securities in connection with the Corporations share incentive plans;
(c) any issuance of securities in connection with a shareholder rights plan; (d) any issuance of securities pursuant to the acquisition of another person (as defined by applicable corporate legislation) by the Corporation as approved by
the board of directors of the Corporation by take-over bid, arrangement, consolidation, merger, purchase of assets, or other reorganization in which the Corporation acquires, in a single transaction or series of related transactions, all or
substantially all assets of such other person, or 50% or more of the equity ownership or voting power of such other person; and (e) any other financing completed in connection with or conditional on the completion of the Business Combination.
Pro Rata Share means, with respect to the Subscriber, the proportion that the number of common shares of the Corporation held by the Subscriber bears to the aggregate total issued and outstanding number of common shares of the
Corporation immediately prior to such issuance. The Corporation shall provide to the Subscriber prior written notice containing the relevant particulars of any proposed issuance (which may provide a range of prices at which shares will be issued) to
which such Pre-emptive Rights apply (Issuance Notice) and the Subscriber shall, within 5 days of receipt of such Issuance Notice (24 hours in the case of a proposed bought deal financing as described under Part 7 of National
Instrument 44-101  Short Form Prospectus Distributions, or any successor rule or policy), provide to the Corporation written notice of whether it intends to exercise its Pre-emptive Rights.

Closing

10. The Subscriber agrees to
deliver to the Corporation, not later than 5:00 p.m. (Vancouver time) on the business day prior to the Closing Date either (a) a certified cheque or bank draft payable to Tekmira Pharmaceuticals Corporation for the Aggregate Subscription Amount
subscribed for under this Subscription Agreement, or (b) funds in the Aggregate Subscription Amount by way of wire transfer to the account of

or payment of the same amount in such other manner as is acceptable to the Corporation.

11. The sale of the Shares pursuant to this
Subscription Agreement will be completed at the offices of Lang Michener LLP, the Corporations counsel, in Vancouver, British Columbia at the Closing Time, at which time certificates representing the Shares will be available against payment of
the Aggregate Subscription Amount for delivery to the Subscriber as the Subscriber shall instruct.

12. The parties hereto agree that their
obligations under this Subscription Agreement are conditional upon:



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(a) the receipt of Exchange approval of (i) the Offering and (ii) the listing of
the Shares on the Exchange, on or before May 30, 2008, in a manner consistent with the Exchanges letter to counsel for the Corporation dated March 19, 2008;

(b) [Reserved]

(c) the prior or concurrent completion of the proposed
business combination between the Corporation and Protiva, as announced on March 30, 2008 (Business Combination) in accordance with the terms and conditions of the Tekmira-Protiva Share Purchase Agreement, without any amendment,
supplement, modification, waiver or consent by any party to the Tekmira-Protiva Share Purchase Agreement of any provision of the Tekmira-Protiva Share Purchase Agreement or the rights or obligations thereof, except as may be consented to by the
Subscriber, acting reasonably and without undue delay;

(d) the Corporation and the Subscriber having negotiated, obtained all
requisite corporate, governmental and third party approvals, and duly executing and delivering:

(i) an amendment and
restatement of the License and Collaboration Agreement effective January 8, 2007 between the Subscriber and the Corporation (as the assignee of Inex Pharmaceuticals Corporation) to account for, among other things, the Business Combination and
the sale of the Shares pursuant to this Subscription Agreement; and

(ii) an amendment and restatement of the Cross License
Agreement effective August 14, 2007 between the Subscriber and Protiva to account for, among other things, the Business Combination and the sale of the Shares pursuant to this Subscription Agreement;

(e) the Subscriber, the Corporation and Protiva having negotiated, obtained all requisite governmental and third party approvals, and
having duly executed and delivered a licence agreement on terms and conditions satisfactory to the Subscriber in its sole and absolute discretion;

(f) the Subscriber and Roche (or any affiliate thereof) having negotiated, obtained all requisite governmental and third party approvals, and having duly executed and delivered an amendment of the License
Agreement dated July 9, 2007 between the Subscriber and an affiliate of Roche on terms and conditions satisfactory to the Subscriber in its sole and absolute discretion;

(g) the dismissal of the litigation between and among the Corporation, Protiva and other named defendants and third parties pending in the British Columbia Supreme Court as Court File No. S-061992 as
contemplated by the form of consent dismissal order attached as Appendix D to the Tekmira-Protiva Share Purchase Agreement, including the entry of such order in such form, and without any of the parties entering into any written agreement,
acknowledgment, waiver, consent or other binding obligation among some or all of such parties concerning the claims raised in such litigation or the intellectual property owned or controlled by any such party that is not approved by the Subscriber
prior to the Closing Time;

(h) receipt by the Subscriber of the First Amendment and Conditional Termination of Loan and
Security Agreement between the Subscriber and the Corporation dated March 28, 2008;

(i) the representations and warranties of
each party herein and the representations and warranties made by each of the Corporation and Protiva in the Tekmira-Protiva Share Purchase Agreement being true and correct both as of the execution of this Subscription Agreement and as of the Closing
Time, provided that for the purposes of this §12(i) the truthfulness and correctness of such representations and warranties will be determined without the benefit of any materiality qualification, including any Material Adverse Affect
qualification, forming part of or otherwise qualifying such representations and warranties, and the covenants of each party herein have been complied with to the extent applicable prior to the Closing Time, except as affected by transactions,
changes, conditions, events or circumstances contemplated or permitted by the Tekmira-Protiva Share Purchase Agreement or for breaches of representations and warranties which individually or in the aggregate do not have a Material Adverse Effect on
the breaching party and would



- 13 -



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not reasonably be expected to have a Material Adverse Effect on the breaching party immediately following the Closing Time;

(j) the receipt by the Subscriber of a favourable legal opinion dated the Closing Date from legal counsel for the Corporation, in form and
substance satisfactory to the Subscriber, acting reasonably, with respect to the following:

(i) the
incorporation, continuance, amalgamation or organization and the existence of the Corporation and each subsidiary under the laws of its jurisdiction of incorporation, continuance, amalgamation or organization, as applicable and is current and
up-to-date with all material filings required to be made by it under such jurisdictions;

(ii) the authorized
and issued share capital of the Corporation;

(iii) the number of shares of Protiva and each other subsidiary
of which the Corporation is the sole registered holder;

(iv) the attributes of the Shares being consistent in
all material respects with their description hereof;

(v) the Corporation having all requisite corporate power
and authority under the laws of its jurisdiction of incorporation, continuance, amalgamation or organization to carry on its business as conducted by it and to own, lease and operate its property and assets in all jurisdictions in which such
business is conducted;

(vi) the Corporation and subsidiary being qualified to carry on business and own or
lease and operate its property and assets under the laws of its jurisdiction of incorporation, amalgamation or organization and in all jurisdictions in which such business is now conducted;

(vii) all necessary corporate action having been taken by the Corporation to authorize the execution and delivery of the
Subscription Agreement;

(viii) the corporate power and capacity of the Corporation to enter into and perform,
and the authorization, execution and delivery of, this Agreement and the enforceability of this Subscription Agreement, except (i) as enforcement thereof may be limited by bankruptcy, insolvency, reorganization, moratorium or similar laws
affecting the rights of creditors generally, (ii) as limited by the application of equitable principles when equitable remedies are sought, (iii) that rights to indemnity and contribution may be limited under applicable law, (iv) that
provisions that attempt to sever any provision of which is prohibited or unenforceable under applicable law without affecting the enforceability or validity of the remainder of the agreement would be determined only in the discretion of the court,
and (v) other standard qualifications;

(ix) the Shares having been duly and validly authorized, issued
and are outstanding as fully paid and non-assessable common shares of the Corporation, and if and when issued in accordance with this Subscription Agreement;

(xii) no consent, approval, authorization, order, registration or qualification of, or filing, registration or recording with, any court, regulatory body or government agency or body under the laws of the
applicable jurisdictions and the laws of Canada being required for the consummation by the Corporation of the transactions contemplated by this Subscription Agreement, except for those which are disclosed to the Subscriber or may be required under
the Securities Laws or the rules of the Exchange and have been obtained on or prior to the Closing Time;

(xiii) that the execution and delivery of this Agreement and the performance of the Corporations obligations
hereunder and the issuance, sale and delivery of the Shares do not and will not



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result in a breach of or default under, and do not and will not create a state of facts which, after notice or lapse of time or both, will result in a breach of or default under, and do not and
will not conflict with:

(A) any of the terms, conditions or provisions of the articles or by-laws of the
Corporation, or any resolution of their respective directors (or committees of directors) or shareholders;

(B)
any Laws of British Columbia, Canada or Securities Laws applicable to the Corporation; or

(C) to
counsels knowledge, any mortgage, hypothec, note, indenture, contract, agreement (written or oral), instrument, concession, lease, licence, claim, application or other document to which the Corporation is a party or is subject or by which the
Corporation or any of its assets is bound or, any applicable law or would give rise to the acceleration or maturity of any indebtedness or other material liabilities or obligations under any of the foregoing or which would materially adversely
affect the consummation of the Offering;

(xiv) issuance and sale of the Shares to the Subscriber in accordance
with the Subscription Agreements are exempt from the prospectus and registration requirements of applicable Securities Laws and no prospectus will be required to be filed, other than specified forms accompanied by requisite filing fees, no other
documents will be required to be filed, no proceeding taken and no approval, permit, consent or authorization of the securities commissions will be required to be obtained under Applicable Securities Laws to permit such issuance and/or sale;

(xv) that based on letters received from the Exchange, the Shares have been conditionally approved for listing
on the Exchange, subject only to compliance with the customary standard listing conditions;

(xvi) that the
form of the certificate representing the common shares of the Corporation is in compliance with the requirements of the Business Corporations Act (British Columbia);

(xvii) that CIBC Mellon Trust Company has been duly appointed as the registrar and transfer agent of the Corporation;

(xviii) subject to the usual qualifications, that except as disclosed to the Subscriber, to such
counsels knowledge, there is no action, suit, proceeding or inquiry before any court, governmental agency or body, to which the Corporation or any of its subsidiary is a party or to which its property is subject which in any way would
materially and adversely affect the Corporation; and

(xx) such other matters as the Subscriber may reasonably
request; and

(k) [Reserved].

13. The Corporation shall be entitled to rely on delivery of a facsimile copy or electronic copy of executed subscriptions, and acceptance by the Corporation of such facsimile subscriptions shall be
legally effective to create a valid and binding agreement between the Subscriber and the Corporation in accordance with the terms hereof.

Privacy Legislation

14. The Subscriber
acknowledges and consents to the fact that the Corporation is collecting the Subscribers (and any beneficial purchaser for which the Subscriber is contracting hereunder) personal information (as that term is defined under applicable privacy
legislation, including, without limitation, the Personal Information Protection and Electronic Documents Act (Canada) and any other applicable similar replacement or supplemental provincial or federal legislation or laws in effect from time
to time) for the purpose of completing the Subscribers



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subscription. The Subscriber acknowledges and consents to the Corporation retaining the personal information for so long as permitted or required by applicable law. The Subscriber further
acknowledges and consents to the fact that the Corporation may be required by Securities Laws, stock exchange rules and/or Investment Dealers Association of Canada rules to provide regulatory authorities any personal information provided by the
Subscriber respecting itself. In addition to the foregoing, the Subscriber agrees and acknowledges that the Corporation may use and disclose the Subscribers personal information, as follows:

(a) for use and disclosure to the Corporations transfer agent and registrar;

(b) disclosure to securities regulatory authorities (including the Exchange) and other regulatory bodies with jurisdiction with respect to
reports of trade and similar regulatory filings;

(c) disclosure to a governmental or other authority (including the Exchange)
to which the disclosure is required by court order or subpoena compelling such disclosure and where there is no reasonable alternative to such disclosure;

(d) disclosure to professional advisers of the Corporation in connection with the performance of their professional services; or

(e) disclosure to a court determining the rights of the parties under this Subscription Agreement.

Notices

15. Any notice, direction or
other instrument required or permitted to be given to any party hereto shall be in writing and shall be sufficiently given if delivered personally, or transmitted by facsimile tested prior to transmission to such party, as follows:



| |  |                                  |  |                                     |  |                        
| |  | -------------------------------- |  | ----------------------------------- |  | -----------------------
| |  | (a)                              |  | in the case of the Corporation, to:
| |  |                                 
| |  |                                  |  | Tekmira Pharmaceuticals Corporation
| |  |                                  |  | 200  8900 Glenlyon Parkway        
| |  |                                  |  | Burnaby, British Columbia V5J 5J8  
| |  |                                  | 
| |  |                                  |  | Attention:                          |  | Ian C. Mortimer        
| |  |                                  |  |                                     |  | Chief Financial Officer
| |  |                                  |  | Fax:                                |  | (604) 419-3201         
| | 
| |  | with a copy to:                 
| |  |                                 
| |  |                                  |  | Lang Michener LLP                  
| |  |                                  |  | 1500 Royal Centre,                 
| |  |                                  |  | P.O. Box 11117                     
| |  |                                  |  | 1055 West Georgia Street           
| |  |                                  |  | Vancouver, British Columbia        
| |  |                                  |  | V6E 4N7                             |  |                        
| |  |                                  | 
| |  |                                  |  | Attention:                          |  | Leo Raffin             
| |  |                                  |  | Fax:                                |  | (604) 685-7084         
| | 
| |  | and, up to the Closing Time, to:
| |  |                                 
| |  |                                  |  | Protiva Biotherapeutics Inc.       
| |  |                                  |  | 100  3480 Gilmore Way             
| |  |                                  |  | Burnaby, British Columbia V6G 4W7  



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| |  |                                  |  |                                     |  |                                      
| |  | -------------------------------- |  | ----------------------------------- |  | -------------------------------------
| |  |                                  |  | Attention:                          |  | Mark Murray                          
| |  |                                  |  |                                     |  | President and Chief Executive Officer
| |  |                                  | 
| |  |                                  |  | Fax:                                |  | (604) 630-5063                       
| | 
| |  | and, up to the Closing Time, to:
| |  |                                 
| |  |                                  |  | Farris, Vaughan, Wills & Murphy LLP
| |  |                                  |  | 2500 - 700 West Georgia Street     
| |  |                                  |  | Pacific Centre South               
| |  |                                  |  | Vancouver, British Columbia V7Y 1B3
| |  |                                  | 
| |  |                                  |  | Attention:                          |  | R. Hector MacKay-Dunn, Q.C.          
| |  |                                  |  | Fax:                                |  | (604) 661-1730                       

(b) in the case of the
Subscriber, at the address specified on the face page hereof.

Any such notice, direction or other instrument, if delivered personally, shall
be deemed to have been given and received on the day on which it was delivered, provided that if such day is not a business day then the notice, direction or other instrument shall be deemed to have been given and received on the first business day
next following such day and if transmitted by fax, shall be deemed to have been given and received on the day of its transmission, provided that if such day is not a business day or if it is transmitted or received after the end of normal business
hours then the notice, direction or other instrument shall be deemed to have been given and received on the first business day next following the day of such transmission.

Any party hereto may change its address for service from time to time by notice given to each of the other parties hereto in accordance with the foregoing provisions.

General

16. The Corporation agrees that
the representations, warranties and covenants of the Corporation herein will be true and correct both as of the acceptance of this Subscription Agreement and as of the Closing Time and will survive the completion of the issuance of the Shares for a
period of two years thereafter. The representations, warranties and covenants of the Corporation herein are made with the intent that they be relied upon by the Subscriber in making its investment decision and the Corporation agrees to indemnify the
Subscriber against all losses, claims, costs, expenses and damages or liabilities which it may suffer or incur which are caused or arise from an inaccuracy or breach thereof by the Corporation of its representations and warranties herein and
reliance thereon by the Subscriber.

17. The Subscriber agrees that the representations, warranties and covenants of the Subscriber herein
will be true and correct both as of the execution of this Subscription Agreement and as of the Closing Time and will survive the completion of the issuance of the Shares for a period of two years thereafter. The representations, warranties and
covenants of the Subscriber herein are made with the intent that they be relied upon by the Corporation in determining the eligibility of a purchaser of Shares and the Subscriber agrees to indemnify the Corporation against all losses, claims, costs,
expenses and damages or liabilities which it may suffer or incur which are caused or arise from an inaccuracy or breach thereof by the Subscriber of its representations and warranties herein and reliance thereon by the Corporation. The Subscriber
undertakes to immediately notify (i) the Corporation at Tekmira Pharmaceuticals Corporation, 200  8900 Glenlyon Parkway, Burnaby, B.C., V5J 5J8, Attention: Ian C. Mortimer, Chief Financial Officer (Fax Number: (604) 419-3201) and
Lang Michener LLP, 1500 Royal Centre, P.O. Box 11117, 1055 West Georgia Street, Vancouver, B.C., V6E 4N7, Attention: Leo Raffin, (Fax Number: (604) 685-7084) and (ii) and Protiva Biotherapeutics Inc., 100  3480 Gilmore Way, Burnaby,
B.C. V6G 4W7, Attention: Mark Murray, President and Chief Executive Officer (Fax Number: (604) 630-5103) and Farris, Vaughan, Wills & Murphy LLP, 2500  700 West Georgia Street, Vancouver, B.C. V7Y 1B3, Attention: R. Hector
MacKay-Dunn,



- 17 -



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Q.C., (Fax Number: (604) 661-9349), of any material change in any statement or other information relating to the Subscriber set forth herein which takes place prior to the Closing Time.

18. The Subscriber acknowledges and agrees that all costs incurred by the Subscriber (including any fees and disbursements of any special
counsel retained by the Subscriber) relating to the sale of the Shares to the Subscriber shall be borne by the Subscriber.

19. The Subscriber
acknowledges that upon a subscription being accepted by the Corporation, the Corporation will, subject to the terms and conditions set out herein, issue to the Subscriber certificates evidencing the Subscribers ownership of the Shares.

20. The terms and provisions of this Subscription Agreement shall be binding upon and enure to the benefit of the Subscriber and the
Corporation and their respective heirs, executors, administrators, successors and assigns.

21. The contract arising out of this Subscription
Agreement and all documents relating thereto shall be governed by and construed in accordance with the laws of the Province of British Columbia and the federal laws of Canada applicable therein. The parties irrevocably attorn to the exclusive
jurisdiction of the courts of the Province of British Columbia. Time shall be of the essence hereof.

22. Neither party to this Subscription
Agreement may assign all or part of its interest in or to this Subscription Agreement without the consent in writing of the other party hereto.

23. This Subscription Agreement represents the entire agreement of the parties hereto relating to the subject matter hereof and there are no
representations, covenants or other agreements relating to the subject matter hereof except as stated or referred to herein. Neither this Subscription Agreement nor any provision hereof shall be modified, changed, discharged or terminated except by
an instrument in writing signed by the party against whom any waiver, change, discharge or termination is sought.

24. In this Subscription
Agreement (including attachments), references to $ or Cdn. $ are to Canadian dollars, and references to US$ are to United States dollars.



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25. The Corporation hereby accepts the subscription for Shares as set forth on the face page of this
Subscription Agreement on the terms and conditions contained in the Subscription Agreement (including all applicable Schedules) this 28th day of March, 2008.



TEKMIRA PHARMACEUTICALS CORPORATIONPer:

/S/ TIMOTHY M. RUANEAuthorized Signing Officer




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SCHEDULE A

UNITED STATES SUBSCRIBERS REPRESENTATION LETTER

This Representation Letter is being
delivered in connection with the execution and delivery of the Subscription Agreement of the undersigned subscriber (the Subscriber) in connection with the purchase of Shares of the Corporation. Capitalized terms used herein and not
defined herein shall have the meanings ascribed thereto in the Subscription Agreement. The Subscriber represents, warrants and covenants (which representations, warranties and covenants shall survive the Closing Date) on its own behalf and, if
applicable, on behalf of any beneficial purchaser for whom the Subscriber is contracting hereunder to and with the Corporation and acknowledges that the Corporation is relying thereon that:

(a) The Subscriber is purchasing the Shares as principal for its own account and not for the benefit of any other Person and it is a
accredited investor as that term is defined in Rule 501(a) of Regulation D (U.S. Accredited Investor); or subscribing for the Shares as agent for a beneficial principal disclosed on the execution page of this Subscription
Agreement, and the Subscriber is an agent or trustee and each disclosed principal for whom it is acting as a U.S. Accredited Investor and is purchasing as principal for its own account and not for the benefit of any other Person; and the Subscriber
has initialled the category of U.S. Accredited Investor applicable to the Subscriber and any beneficial principal below.

(b)
The provisions of paragraph (a) of this Representation Letter will be true and correct both as of the date of execution of this Subscription Agreement and as of the Closing Date.

(c) The Subscriber has not purchased the Shares as a result of any form of general solicitation or general advertising (as those terms are
used in Regulation D), including advertisements, articles, notices or other communications published in any newspaper, magazine or similar media or broadcast over radio, or television, or any seminar or meeting whose attendees have been invited by
general solicitation or general advertising.

(d) The Corporation has provided the Subscriber with the opportunity to ask
questions and receive answers concerning the terms and conditions of the Offering and the Subscriber has had access to such information concerning the Corporation as it has considered necessary or appropriate in connection with its investment
decision to acquire the Shares.

(e) The Subscriber understands and acknowledges that none of the Shares have been or will be
registered under the U.S. Securities Act or the securities laws of any state, and that the Shares are being offered and sold to a limited number of U.S. Accredited Investors in transactions not requiring registration under the U.S. Securities Act;
accordingly, the Shares will be restricted securities within the meaning of Rule 144(a)(3) of the U.S. Securities Act.

(f) The Subscriber, and each beneficial principal, if any, is acquiring the Shares for investment purposes only and not with a view to any resale, distribution or other disposition of the Shares in
violation of the United States securities laws.

(g) The Subscriber understands that if it (or any beneficial purchaser on
whose behalf it is acting) decides to offer, sell or otherwise transfer any of the Shares, they may be offered, sold or otherwise transferred only (i) to the Corporation, (ii) outside the United States in compliance with Rule 904 of
Regulation S, (iii) in compliance with the exemption from registration under the U.S. Securities Act provided by Rule 144 or Rule 144A thereunder, if available, and in compliance with any applicable state securities laws, or
(iv) in a transaction that does not require registration under the U.S. Securities Act or any applicable state laws and regulations governing the offer and sale of securities and it has prior to such transfer furnished to the Corporation an
opinion of counsel of recognized standing in form and substance satisfactory to the Corporation, and covenants that it will not offer or sell such securities except as set out above.



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(h) The Subscriber understands that upon the original issuance thereof, and until such time
as the same is no longer required under applicable requirements of the U.S. Securities Act or applicable state securities laws, certificates representing the Shares and all certificates issued in exchange therefore or in substitution thereof, shall
bear the following legends:

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE UNITED STATES
SECURITIES ACT OF 1933, AS AMENDED (THE U.S. SECURITIES ACT) OR ANY STATE SECURITIES LAWS, AND MAY BE OFFERED, SOLD OR OTHERWISE TRANSFERRED ONLY (A) TO THE CORPORATION (B) OUTSIDE THE UNITED STATES IN COMPLIANCE WITH
RULE 904 OF REGULATION S UNDER THE U.S. SECURITIES ACT, (C) IN COMPLIANCE WITH THE EXEMPTION FROM REGISTRATION UNDER THE U.S. SECURITIES ACT PROVIDED BY RULE 144 OR 144A THEREUNDER, IF AVAILABLE, AND IN COMPLIANCE WITH ANY APPLICABLE
STATE SECURITIES LAWS, OR (D) IN A TRANSACTION THAT DOES NOT REQUIRE REGISTRATION UNDER THE U.S. SECURITIES ACT OR ANY APPLICABLE STATE LAWS AND REGULATIONS GOVERNING THE OFFER AND SALE OF SECURITIES AND IT HAS PRIOR TO SUCH TRANSFER FURNISHED
TO THE CORPORATION AN OPINION OF COUNSEL OF RECOGNIZED STANDING IN FORM AND SUBSTANCE SATISFACTORY TO THE CORPORATION.

THE PRESENCE OF THIS LEGEND MAY IMPAIR THE ABILITY OF THE HOLDER HEREOF TO EFFECT GOOD DELIVERY OF THE SECURITIES
REPRESENTED HEREBY ON A CANADIAN STOCK EXCHANGE. A CERTIFICATE WITHOUT A LEGEND MAY BE OBTAINED FROM THE REGISTRAR AND TRANSFER AGENT OF THE CORPORATION IN CONNECTION WITH A SALE OF THE SECURITIES REPRESENTED HEREBY AT A TIME WHEN THE CORPORATION IS
A FOREIGN ISSUER AS DEFINED IN REGULATION S UNDER THE U.S. SECURITIES ACT, UPON DELIVERY OF THIS CERTIFICATE, AN EXECUTED DECLARATION AND, IF REQUESTED BY THE CORPORATION OR THE TRANSFER AGENT, AN OPINION OF COUNSEL OF RECOGNIZED
STANDING, EACH IN FORM SATISFACTORY TO THE TRANSFER AGENT OF THE CORPORATION AND THE CORPORATION, TO THE EFFECT THAT SUCH SALE OF THE SECURITIES REPRESENTED HEREBY IS BEING MADE IN COMPLIANCE WITH RULE 904 OF REGULATION S UNDER THE U.S.
SECURITIES ACT.;

provided, that if the securities are being sold outside the United States in compliance with the requirements of
Rule 904 of Regulation S at a time when the Corporation is a foreign issuer as defined in Regulation S at the time of sale, the legends set forth above may be removed by providing an executed declaration to the registrar and
transfer agent of the Corporation, in substantially the forms set forth as Exhibit A-1 hereto (or in such other forms as the Corporation may prescribe from time to time) and, if requested by the Corporation or the transfer agent, an opinion of
counsel of recognized standing in form and substance satisfactory to the Corporation and the transfer agent to the effect that such sale is being made in compliance with Rule 904 of Regulation S; and provided, further, that, if any Shares, if any,
are being sold otherwise than in accordance with Regulation S and other than to the Corporation, the legend may be removed by delivery to the registrar and transfer agent and the Corporation of an opinion of counsel, of recognized standing
reasonably satisfactory to the Corporation, that such legend is no longer required under applicable requirements of the U.S. Securities Act or state securities laws.

(i) The Subscriber understands that the Corporation is under no obligation to remain a foreign issuer (as defined in Regulation S) and may not be a foreign issuer at a time when
the Subscriber wishes to transfer the Shares. The Subscriber further understands and acknowledges that the loss of the



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Corporations foreign issuer status would impede Subscribers ability to remove the restrictive U.S. legends from the Securities in connection with a resale outside the United States.

(j) The Subscriber understands that the Corporation is not obligated to file and has no present intention of filing with the
U.S. Securities and Exchange Commission or with any state securities administrator any registration statement in respect of resales of the Shares in the United States.

(k) The Subscriber understands and agrees that the financial statements of the Corporation have been prepared in accordance with Canadian generally accepted accounting principles, which differ in some
respects from United States generally accepted accounting principles, and thus may not be comparable to financial statements of United States companies.

(l) The Subscriber understands and agrees that there may be material tax consequences to it of an acquisition, holding or disposition of the Shares. The Corporation gives no opinion and makes no
representation with respect to the tax consequences to the Subscriber under United States, state, local or foreign tax law of its acquisition, holding or disposition of such securities, and the Subscriber acknowledges that it is solely responsible
for determining the tax consequences to its investment.

(m) The Subscriber hereby represents and warrants that the Subscriber
(and, if the Subscriber is acting on behalf of a beneficial purchaser, such beneficial purchase) is a U.S. Accredited Investor as a result of satisfying the requirements of the paragraphs below to which the Subscriber has affixed his or her initials
(the line identified as BP is to be initialled by the undersigned if the beneficial purchaser, if any, satisfies the requirements of the corresponding paragraph).



|     |  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|---- |  | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|     |  | A natural person whose individual net worth, or joint net worth with that persons spouse, at the time of his purchase exceeds US$1,000,000;                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|(BP) | 
|     | 
|     |  | Any natural person who had an individual income in excess of US$200,000 in each of the two most recent years or joint income with that persons spouse in excess
of US$300,000 in each of those years and has a reasonable expectation of reaching the same income level in the current year;                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|(BP) | 
|     | 
|     |  | Any entity in which all of the equity owners are U.S. Accredited Investors;                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|(BP) | 
|     | 
|(BP) |  | Any bank as defined in Section 3(a)(2) of the U.S. Securities Act or any savings and loan association or other institution as defined in Section 3(a)(5)(A) of
the U.S. Securities Act whether acting in its individual or fiduciary capacity; any broker or dealer registered pursuant to Section 15 of the Securities Exchange Act of 1934; any insurance company as defined in Section 2(a)(13) of the U.S.
Securities Act; any investment company registered under the Investment Company Act of 1940 or a business development company as defined in Section 2(a)(48) of that Act; any Small Business Investment Company licensed by the U.S. Small Business
Administration under Section 301(c) or (d) of the Small Business Investment Act of 1958; any plan established and maintained by a state, its political subdivisions, or any agency or instrumentality of a state or its political subdivisions, for the
benefit of its employees, if such plan has total assets in excess of US$5,000,000; any employee benefit plan within the meaning of the Employee Retirement Income Security Act of 1974, if the investment decision is made by a plan fiduciary, as
defined in Section 3(21) of such Act, which is either a bank, savings and loan association, insurance company, or registered investment adviser, or if the employee benefit plan has total assets in excess of US$5,000,000, or, if a self-directed plan,
with investment decisions made solely by persons that are U.S. Accredited Investors;
|    
|     | 
|     |  | Any private business development company as defined in Section 202(a)(22) of the Investments Advisers Act of 1940;                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|(BP) | 



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|     |  |                                                                                                                                                                                                                                                                                                                                                                                      
|---- |  | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|     |  | Any organization described in section 501(c)(3) of the Internal Revenue Code, corporation, Massachusetts or similar business trust, or partnership not formed for the
specific purpose of acquiring the Purchased Securities, with total assets in excess of US$5,000,000;                                                                                                           
|(BP) | 
|     | 
|     |  | Any director or executive officer of the Corporation;                                                                                                                                                                                                                                                                                                                                
|(BP) | 
|     | 
|(BP) |  | Any trust with total assets in excess of US$5,000,000, not formed for the specific purpose of acquiring the Purchased Securities, whose purchase is directed by a
sophisticated person, being defined as a person who has such knowledge and experience in financial and business matters that he or she is capable of evaluating the merits and risks of the prospective investment.
|    

DATED at
 this day of , 2008.



By:Name:Title:




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EXHIBIT A-1

FORM OF DECLARATION FOR REMOVAL OF LEGEND



|        |  |                                                                                           
|------- |  | ------------------------------------------------------------------------------------------
|TO:     |  | Tekmira Pharmaceuticals Corporation                                                       
|        | 
|AND TO: |  | The registrar and transfer agent for the securities of Tekmira Pharmaceuticals Corporation

The undersigned (A) acknowledges that the sale of the securities of Tekmira Pharmaceuticals Corporation (the Corporation) to which this declaration relates is being made in reliance on
Rule 904 of Regulation S under the United States Securities Act of 1933, as amended (the U.S. Securities Act) and (B) certifies that (1) the undersigned is not an affiliate of the Corporation as that term is
defined in Rule 405 under the U.S. Securities Act, a distributor or an affiliate of distributor, (2) the offer of such securities was not made to a person in the United States and either (a) at the time the buy
order was originated, the buyer was outside the United States, or the seller and any person acting on its behalf reasonably believed that the buyer was outside the United States or (b) the transaction was executed on or through the facilities
of a designated offshore securities market (as defined in Rule 902 of the U.S. Securities Act) and neither the seller nor any person acting on its behalf knows that the transaction has been prearranged with a buyer in the United States,
(3) neither the seller nor any affiliate of the seller nor any person acting on their behalf has engaged or will engage in any directed selling efforts in the United States in connection with the offer and sale of such securities,
(4) the sale is bona fide and not for the purpose of washing-off the resale restrictions imposed because the securities are restricted securities as that term is described in Rule 144(a)(3) under the U.S. Securities
Act, (5) the seller does not intend to replace such securities sold in reliance on Rule 904 of the U.S. Securities Act with fungible unrestricted securities, and (6) the contemplated sale is not a transaction, or part of a series of
transactions, which, although in technical compliance with Regulation S, is part of a plan or scheme to evade the registration provisions of the U.S. Securities Act. Unless otherwise specified, terms set forth above in quotation marks have the
meanings given to them by Regulation S promulgated under the U.S. Securities Act.



|       |  | 
|------ |  | 
|DATED: |  | 



By:Name:Title:




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AFFIRMATION BY SELLERS BROKER-DEALER

We have read the foregoing representations of our customer,
 (the Seller) dated
, with regard to the sale, for such Sellers account, of the
 represented by certificate number
 of the Corporation described therein, and we hereby affirm that, to the
best of our knowledge and belief, the facts set forth therein are full, true and correct.



|             |  |                   
|------------ |  | ------------------
|            
|Name of Firm
|             | 
|By:          |  |                   
|             |  | Authorized officer



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