AGREEMENT AND PLAN OF MERGER

Exhibit 2.1

AGREEMENT AND PLAN OF MERGER

THIS AGREEMENT AND PLAN OF MERGER (hereinafter referred to as this “Agreement”) dated as of October 17, 2005, is made and entered into by and between Vyrex Corporation, a Nevada corporation (the “Parent”) and Vyrex (Delaware) Corporation, a Delaware corporation (the “Subsidiary”).

RECITALS

A. The Parent is a corporation organized and existing under the laws of the State of Nevada.

B. The Subsidiary is a corporation organized and existing under the laws of the State of Delaware and is a wholly-owned subsidiary of the Parent.

C. The Parent and the Subsidiary and their respective Boards of Directors deem it advisable and to the advantage, welfare, and best interests of the corporations and their respective stockholders to merge Parent with and into Subsidiary pursuant to the provisions of Nevada Revised Statutes (the “NRS”) and the Delaware General Corporation Law (the “DGCL”) upon the terms and conditions hereinafter set forth.

NOW THEREFORE, in consideration of the premises, the mutual covenants herein contained and other good and valuable consideration the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree that the Parent shall be merged into the Subsidiary (the “Merger”) upon the terms and conditions hereinafter set forth.

ARTICLE I

PRINCIPAL TERMS OF THE MERGER

1.1 Merger. On the Effective Date (as defined in Section 4.1 hereof), the Parent shall be merged into the Subsidiary, the separate existence of the Parent shall cease and the Subsidiary (following the Merger referred to as the “Surviving Corporation”) shall operate under the name “Vyrex Corporation” by virtue of, and shall be governed by, the laws of the State of Delaware. The address of the registered office of the Surviving Corporation in the State of Delaware will be 2711 Centerville Road, Suite 400, City of Wilmington, County of Newcastle, and the registered agent in charge thereof shall be Corporation Service Company.

1.2 Certificate of Incorporation of the Surviving Corporation. The Certificate of Incorporation of the Surviving Corporation shall be the Certificate of Incorporation of the Subsidiary as in effect on the date hereof without change unless and until amended in accordance with applicable law.

1.3 Bylaws of the Surviving Corporation. The Bylaws of the Surviving Corporation shall be the Bylaws of the Subsidiary as in effect on the date hereof without change unless and until amended or repealed in accordance with applicable law.

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1.4 Directors and Officers. At the Effective Date of the Merger, the directors and officers of the Subsidiary in office at the Effective Date of the Merger shall become the directors and officers, respectively, of the Surviving Corporation, each of such directors and officers to hold office, subject to the applicable provisions of the Certificate of Incorporation and Bylaws of the Surviving Corporation and the DGCL, until his or her successor is duly elected or appointed and qualified.

ARTICLE II

CONVERSION, CERTIFICATES AND PLANS

2.1 Conversion of Shares. At the Effective Date of the Merger, each of the following transactions shall be deemed to occur simultaneously:

(a) Common Stock. Each share of the Parent’s common stock, $0.001 par value per share (the “Parent’s Common Stock”), issued and outstanding immediately prior to the Effective Date of the Merger (except for those shares of the Parent’s Common Stock with respect to which the holders thereof duly exercise their dissenters’ rights under the NRS), by virtue of the Merger and without any action on the part of the holder thereof, shall be converted into and become one validly issued, fully paid and nonassessable share of the Surviving Corporation’s common stock, $0.0001 par value per share (the “Surviving Corporation’s Common Stock”) multiplied by the Conversion Ratio (as defined below). Any holder’s fractional share of the Surviving Corporation’s Common Stock resulting from the foregoing conversion shall be rounded up to the next whole number. The “Conversion Ratio” shall be a fraction the numerator of which is 12 and the denominator of which is 100.

(b) Options. Each option to acquire shares of the Parent’s Common Sock outstanding immediately prior to the Effective Date of the Merger shall, by virtue of the Merger and without any action on the part of the holder thereof, be converted into and become an equivalent option to acquire, upon the same terms and conditions, the number of shares of the Surviving Corporation’s Common Stock, which is equal to the number of shares of the Parent’s Common Stock that the optionee would have received had the optionee exercised such option in full immediately prior to the Effective Date of the Merger (whether or not such option was then exercisable) multiplied by the Conversion Ratio and the exercise price per share under each of said options shall be equal to the exercise price per share thereunder immediately prior to the Effective Date of the Merger divided by the Conversion Ratio, unless otherwise provided in the instrument granting such option.

(c) Warrants. Each warrant to acquire shares of the Parent’s Common Stock outstanding immediately prior to the Effective Date of the Merger shall, by virtue of the Merger and without any action on the part of the holder thereof, be converted into and become a warrant to acquire, upon the same terms and conditions, the number of shares of the Surviving Corporation’s Common Stock which is equal to the number of shares of the Parent’s Common Stock that the warrant holder would have received had the warrant holder exercised such warrant in full immediately prior to the Effective Date of the Merger (whether or not such warrant was then exercisable) multiplied by the Conversion Ratio and the exercise price per share under each of said warrants shall be equal to the exercise price per share thereunder

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immediately prior to the Effective Date of the Merger divided by the Conversion Ratio, unless otherwise provided in the instrument granting such warrant.

(d) Other Rights. Any other right, by contract or otherwise, to acquire shares of the Parent’s Common Stock outstanding immediately prior to the Effective Date of the Merger shall, by virtue of the Merger and without any action on the part of the holder thereof, be converted into and become a right to acquire, upon the same terms and conditions, the number of shares of the Surviving Corporation’s Common Stock which is equal to the number of shares of the Parent’s Common Stock that the right holder would have received had the right holder exercised such right in full immediately prior to the Effective Date of the Merger (whether or not such right was then exercisable) multiplied by the Conversion Ratio and the exercise price per share under each of said rights shall be equal to the exercise price per share thereunder immediately prior to the Effective Date of the Merger divided by the Conversion Ratio, unless otherwise provided in the agreement granting such right.

(e) Each share of the Subsidiary’s Common Stock issued and outstanding immediately prior to the Effective Date of the Merger and held by the Parent shall be canceled without any consideration being issued or paid therefor.

2.2 Stock Certificates. After the Effective Date of the Merger, each certificate theretofore representing issued and outstanding shares of the Parent’s Common Stock will thereafter be deemed to represent the number of shares of the Surviving Corporation’s Common Stock equal to the number of shares shown on the face of such certificate multiplied by the Conversion Ratio. The holders of outstanding certificates theretofore representing the Parent’s Common Stock will not be required to surrender such certificates to the Parent.

2.3 Employee Benefit and Compensation Plans. At the Effective Date of the Merger, each employee benefit plan, incentive compensation plan and other similar plans to which the Parent is then a party shall be assumed by, and continue to be the plan of, the Surviving Corporation. To the extent any employee benefit plan, incentive compensation plan or other similar plan of the Parent provides for the issuance or purchase of, or otherwise relates to, the Parent’s Common Stock, after the Effective Date of the Merger such plan shall be deemed to provide for the issuance or purchase of, or otherwise relate to, the Surviving Corporation’s Common Stock (with all share amounts and purchase or exercise prices being appropriately adjusted by the Conversion Ratio).

ARTICLE III

TRANSFER AND CONVEYANCE OF ASSETS AND ASSUMPTION OF LIABILITIES

3.1 Effects of the Merger. At the Effective Date of the Merger, the Merger shall have the effects specified in the NRS, the DGCL and this Agreement. Without limiting the generality of the foregoing, and subject thereto, at the Effective Date of the Merger, the Surviving Corporation shall possess all the rights, privileges, powers and franchises, of a public as well as a private nature, and shall be subject to all the restrictions, disabilities and duties of each of the parties to this Agreement; the rights, privileges, powers and franchises of the Parent and the Subsidiary, and all property, real, personal and mixed, and all debts due to

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each of them on whatever account, shall be vested in the Surviving Corporation; and all property, rights, privileges, powers and franchises, and all and every other interest shall be thereafter the property of the Surviving Corporation, as they were of the respective constituent entities, and the title to any real estate whether by deed or otherwise vested in the Parent and the Subsidiary or either of them, shall not revert to be in any way impaired by reason of the Merger; but all rights of creditors and all liens upon any property of the parties hereto, shall be preserved unimpaired, and all debts, liabilities and duties of the respective constituent entities shall thenceforth attach to the Surviving Corporation, and may be enforced against it to the same extent as if said debts, liabilities and duties had been incurred or contracted by it.

3.2 Additional Actions. If, at any time after the Effective Date of the Merger, the Surviving Corporation shall consider or be advised that any further assignments or assurances in law or any other acts are necessary or desirable (a) to vest, perfect or confirm, of record or otherwise, in the Surviving Corporation, title to and possession of any property or right of the Parent acquired or to be acquired by reason of, or as a result of, the Merger, or (b) otherwise to carry out the purposes of this Agreement, the Parent and its proper officers and directors shall be deemed to have granted to the Surviving Corporation an irrevocable power of attorney to execute and deliver all such proper deeds, assignments and assurances in law and to do all acts necessary or proper to vest, perfect or confirm title to and possession of such property or rights in the Surviving Corporation and otherwise to carry out the purposes of this Agreement. The proper officers and directors of the Surviving Corporation are fully authorized in the name of the Parent or otherwise to take any and all such action.

ARTICLE IV

APPROVAL BY STOCKHOLDERS; AMENDMENT; EFFECTIVE DATE

4.1 Approval. This Agreement and the Merger contemplated hereby are subject to approval by the requisite vote of stockholders in accordance with the NRS and the DGCL. As promptly as practicable after approval of this Agreement by stockholders in accordance with applicable law, duly authorized officers of the respective parties shall make and execute Articles of Merger and a Certificate of Merger and shall cause such documents to be filed with the Secretary of State of Nevada and the Secretary of State of Delaware, respectively, in accordance with the laws of the States of Nevada and Delaware. The effective date (the “Effective Date”) of the Merger shall be the date on which the Merger becomes effective under the laws of Nevada or the date on which the Merger becomes effective under the laws of Delaware, whichever occurs later.

4.2 Amendments. The Board of Directors of the Parent may amend this Agreement at any time prior to the Effective Date, provided that an amendment made subsequent to the approval of the Merger by the stockholders of the Parent shall not (a) alter or change the amount or kind of shares to be received in exchange for or on conversion of all or any of the shares of the Parent’s Common Stock, (b) alter or change any term of the Certificate of Incorporation of the Subsidiary, or (c) alter or change any of the terms and conditions of this Agreement if such alteration or change would adversely affect the holders of the Parent’s Common Stock.

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ARTICLE V

MISCELLANEOUS

5.1 Termination. This Agreement may be terminated and the Merger abandoned at any time prior to the filing of this Agreement with the Secretary of State of Nevada and the Secretary of State of Delaware, whether before or after stockholder approval of this Agreement, by the consent of the Boards of Directors of the Parent and the Subsidiary.

5.2 Counterparts. This Agreement may be executed in any number of counterparts, each of which shall be considered to be an original instrument.

5.3 Descriptive Headings. The descriptive headings are for convenience of reference only and shall not control or affect the meaning or construction of any provision of this Agreement.

5.4 Governing Law. This Agreement shall be construed in accordance with the laws of the State of Delaware, except to the extent the laws of the State of Nevada shall apply to the Merger where mandated by the NRS.

IN WITNESS WHEREOF, the undersigned officers of each of the parties to this Agreement, pursuant to authority duly given by their respective Boards of Directors, have caused this Agreement to be duly executed on the date set forth above.

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