**EXHIBIT
      10.15**





**REVOCATION
      OF ASSIGNMENT**







THIS
      REVOCATION (the “Revocation of Assignment”) to the ASSIGNMENT AGREEMENT (the
“Assignment”) is effective as of the 1 st day of
      June 2005 (“Effective Date”) by and between FIRST COVENTRY CORPORATION, a
      Delaware corporation having offices at 99 Derby Street, Suite 200, Hingham,
      MA
      02043 (“ FIRST
      COVENTRY ”),
      and
      PATHOGENICS CORPORATION, a Delaware corporation having offices at 99 Derby
      Street, Suite 200, Hingham, MA 02043 (“PATHOGENICS”).





WHEREAS,
      on May 25, 2005 PATHOGENICS entered into a certain license agreement for
      Chloroquine patents and patent applications between PATHOGENICS (as exclusive,
      worldwide Licensee) and Alpha Research Group, LLC and Jodi A. Nelson
      (collectively, the Licensors), a copy of which is attached hereto as Exhibit
      A
      (“License Agreement”);





WHEREAS,
      on May 25, 2005 the PATHOGENICS board of directors resolved by unanimous written
      consent of its disinterested directors to purchase three-thousand (3,000) shares
      representing one-hundred percent (100%) of the authorized common stock (the
      Shares) of FIRST COVENTRY, a copy of which is attached hereto as Exhibit B
      (“Unanimous Consent”);





WHEREAS,
      on May 25, 2005 pursuant to the Unanimous Consent PATHOGENICS issued a note
      and
      security agreement in the amount of $20,000 at 8% APR to William K. Mackey
      and
      William L. Sklar, which grants a security interest in the Shares, a copy of
      which is attached hereto as Exhibit C (“Note and Security
      Agreement”);





WHEREAS,
      on May 25, 2005 PATHOGENICS Assigned to FIRST COVENTRY all of PATHOGENICS’
rights and obligations under the License Agreement against its receipt of the
      Shares, a copy of which is attached hereto as Exhibit D (“Assignment”). The
      Unanimous Consent, the Investment Agreement, and the Note and Security Agreement
      are silent as to the nature of the consideration PATHOGENICS conveys to FIRST
      COVENTRY in return for the Shares. Accordingly, PATHOGENICS and FIRST COVENTRY
      both desire to revoke the Assignment as consideration for the Shares of FIRST
      COVENTRY, and substitute in its place $20,000 worth of shares of common stock
      of
      PATHOGENICS in consideration for the Shares of FIRST COVENTRY;





WHEREAS,
      on June 1, 2005 pursuant to the Unanimous Consent PATHOGENICS entered into
      the
      Investment Agreement with FIRST COVENTRY, thereby buying the Shares and making
      FIRST COVENTRY the wholly owned subsidiary of PATHOGENICS, a copy of which
      is
      attached hereto as Exhibit E. The Investment Agreement requires that PATHOGENICS
      acquire the Shares for its own account and for investment purposes only, within
      the meaning of the Securities Act of 1933 (the Act), with no intention of
      assigning any participation or interest therein, and not with a view to the
      distribution thereof. Furthermore, PATHOGENICS may not transfer or assign its
      rights under the Investment Agreement, and that the assignment and
      transferability of the Shares is restricted. As a result, PATHOGENICS’ granting
      of a security interest in the Shares by the Note and Security Agreement was
      ineffective. Accordingly, PATHOGENICS and FIRST COVENTRY both desire to amend
      the Investment Agreement to allow PATHOGENICS to freely grant a security
      interest in the Shares, and give full force and effect to the granting of a
      security interest in the Shares by the Note and Security Agreement;




-1-





NOW,
      THEREFORE, in consideration of the foregoing premises and the mutual covenants
      and agreements hereinafter set forth, and for other good and valuable
      consideration described below, the receipt and sufficiency of which are hereby
      acknowledged, the Parties hereto agree as follows:





1.  FIRST
      COVENTRY and PATHOGENICS hereby revoke, rescind and cancel the Assignment to
      FIRST COVENTRY of all of PATHOGENICS’ rights and obligations under the License
      Agreement thereby restoring the Parties to their pre-Assignment status.





2.  FIRST
      COVENTRY hereby assigns, transfers, conveys and relinquishes exclusively to
      PATHOGENICS, its lawful successors and assigns, all of FIRST COVENTRY’s rights
      and obligations under the Assignment and License Agreement.





3.  PATHOGENICS
      assumes, and agrees to pay and perform, all unperformed obligations of FIRST
      COVENTRY under the Assignment and License Agreement. PATHOGENICS agrees that
      by
      executing and delivering this Agreement PATHOGENICS shall become the sole
      existing party amongst them to the License Agreement and agrees to be bound
      by
      all of the terms and provisions of the License Agreement.





4.  In
      furtherance of this Agreement, FIRST COVENTRY hereby acknowledges that, from
      the
      Effective Date forward, PATHOGENICS has succeeded to all of FIRST COVENTRY’s
      rights, obligations, title, and standing in relation to the License Agreement,
      to institute and prosecute all suits and proceedings, to take all actions that
      PATHOGENICS, in its sole discretion, may deem necessary or proper to collect,
      assert, or enforce any claim, right, or title of any kind under the License
      Agreement, whether arising before or after the Effective Date, to defend and
      compromise any and all such actions, suits, or proceedings relating to such
      transferred and assigned rights, title, interest, and benefits, and to do all
      other such acts and things in relation thereto as PATHOGENICS in its sole
      discretion deems advisable.





5.  FIRST
      COVENTRY and PATHOGENICS agree to amend the Investment Agreement to allow
      PATHOGENICS’ grant of a security interest in the Shares in accordance with the
      terms of the Note and Security Agreement, and allow their unrestricted
      assignment or transfer in the event of PATHOGENICS’ default thereon, a copy of
      which is attached hereto as Exhibit F (the “First Amendment to the Investment
      Agreement”).





6.  PATHOGENICS
      agrees to amend the Investment Agreement to instruct its transfer agent on
      the
      first anniversary of the effective date of the Investment Agreement, June 1,
      2006, to issue FIRST COVENTRY $20,000 worth of its common stock, the value
      of
      which is attributed by the Parties to be $0.029 per share on the effective
      date
      of the Investment Agreement, June 1, 2005, for a total of 689,655 shares of
      the
      PATHOGENICS’ common stock, together with an appropriate instruction and opinion
      of counsel directing the delivery of these shares of common stock without any
      restrictive legends pursuant to Rule 144 under the 1933 Act.




-2-





7.  FIRST
      COVENTRY represents and warrants that, to the best of FIRST COVENTRY’s
      knowledge, upon consummation of this Agreement, PATHOGENICS shall have good
      and
      marketable title to the License Agreement, free and clear of any and all liens,
      mortgages, encumbrances, pledges, security interests, licenses, or charges
      of
      any nature whatsoever.





8.  This
      Agreement shall inure to the benefit of, and be binding upon, the parties hereto
      together with their respective legal representatives, successors and
      assigns.





9.  This
      Agreement shall be governed by and construed in accordance with the laws of
      the
      Commonwealth of Massachusetts (excluding conflicts of law rules) and of the
      United States of America.





10.  This
      Agreement merges and supersedes all prior and contemporaneous agreements,
      assurances, representations, and communications between or among the parties
      hereto concerning the matters set forth herein.





11.  If
      a
      dispute arises out of or relates to this Agreement, or a breach thereof, and
      if
      the dispute cannot be settled through negotiation, the parties agree to first
      try in good faith to settle the dispute by mediation administered by the
      American Arbitration Association under its Commercial Mediation Rules before
      resorting to arbitration, litigation, or some other dispute resolution
      procedure.





12.  Any
      claim
      or controversy arising out of or relating to this Agreement, or the breach
      thereof, that cannot be settled through mediation shall be settled by
      arbitration administered by the American Arbitration Association under its
      Commercial Arbitration Rules, and judgment o the award rendered by the
      arbitrator may be entered in any court having jurisdiction thereof.





IN
      WITNESS WHEREOF, the parties hereto have executed this Agreement the day and
      year first written below.




FIRST
                  COVENTRYCORPORATION
              
              PATHOGENICS,
                  INC.By:/s/
                  Frederic P. Zotos
              
              By:/s/
                  Frederic P. ZotosName:
                  Frederic P. Zotos, Esq.
              
              Name:
                  Frederic P. Zotos, Esq.Title:
                  President & CEO
              
              Title:
                  President & CEODate:
                  March 20, 2006
              
              Date:
                  March 20, 2006-3-