<PAGE>

                                                                   Exhibit 10.80

                        [Calypte Biomedical Letterhead]

                                November 14, 2000

William Boeger
Box 2706
Sun Valley, ID 83353

         Re:      Extension of Your Consulting Agreement With Calypte
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Dear Bill:

         Upon your signature at the end of this letter where indicated, this
letter will be a binding amendment to extend (the "EXTENSION") the Consulting
Agreement between Calypte Biomedical Corporation ("CALYPTE") and you dated as of
October 18, 1999 (the "CONSULTING AGREEMENT"), with respect to your provision of
service as a consultant to Calypte as provided in this letter (the services
described in Section 1 hereof are referred to herein as the "SERVICES"). This
Extension shall be effective as of October 18, 2000 (the "EFFECTIVE DATE"). With
the exception of the sections amended in their entirety below, all other
sections of the Agreement will remain in effect until the termination of this
Extension.

         1.       SERVICES.


                  (a)   BASIC RETAINED SERVICES. Subject to the terms and
conditions of this Agreement, you hereby are retained by Calypte as a consultant
to Calypte from the Effective Date until terminated as provided herein, to
provide the following Services:



                        (i)     FULL-TIME CONSULTING SERVICES THROUGH NOVEMBER
30, 1999. This Section is not applicable for the term of the Extension.



                        (ii)    PART-TIME CONSULTING SERVICES FROM OCTOBER 18,
2000 THROUGH OCTOBER 18, 2001. During the period commencing with October 18,
2000 through and including October 18, 2001 (the "PART-TIME PERIOD"), you will
provide, on a part-time basis for an aggregate of one day of Services per
calendar month Services relating to certain strategic matters, including but not
limited to assisting Calypte with the distribution of its products to China,
assisting Calypte with its ongoing relationship with and investment in Pepgen
Corporation and with other matters as may be requested from time to time during
the term hereof orally or in writing by the President, Chief Executive Officer
or the Chairman of Calypte.
<PAGE>

William Boeger
November 14, 2000
Page 2


                  (b)   ADDITIONAL SERVICES. During the period of this
Extension, you will render such days of Services beyond such one day minimum set
forth in Section 2(b)(ii) hereof (the "ADDITIONAL SERVICES"), as you may agree
with Calypte upon Calypte's reasonable and good faith request to you, in each
case with respect to Calypte's business, as may be requested from time to time
during the term hereof orally or in writing by the Board or by the President,
Chief Executive Officer or the Chairman of Calypte.

                  (c) - (g) No Change. These Sections shall remain in effect as
set forth in the Consulting Agreement until the termination of this Extension.


         2.       COMPENSATION, EXPENSE REIMBURSEMENT; CESSATION OF VESTING OF
STOCK OPTION.

                  (a)   RETAINER FOR SERVICES. Calypte will pay you a retainer,
in cash, at the beginning of each calendar month for twelve months commencing
with the month of October, 2000 in the amount of five hundred dollars ($500.00)
per month.

                  (b)   NO CHANGE. This Section shall remain in effect as set
forth in the Consulting Agreement until the termination of this Extension.

                  (c)   EXPENSE REIMBURSEMENT; LODGING AND AUTOMOBILE; CESSATION
OF HEALTH INSURANCE. Calypte will reimburse you for all reasonable, ordinary and
necessary travel and entertainment expenses incurred by you in conjunction with
your services to Calypte hereunder. Any such expense will be consistent with
Calypte's then-standard reimbursement policy, and, as applicable, travel policy,
and will be made as to a given expense only if you have submitted commercially
customary support documentation to Calypte therefor. If you so request, Calypte
will provide non-monetary assistance to you to arrange for continuing coverage
under Calypte's healthcare insurance for you and your family consistent with
Calypte's standard policies for healthcare insurance coverage for former
employees and with federal COBRA guidelines. In addition, on the Effective Date,
Calypte will cease its reimbursements to you for the amount of premiums you pay
during the term hereof for healthcare insurance for you and your family to the
extent you are not covered for such healthcare insurance under a Calypte
healthcare insurance plan pursuant to Calypte's standard policies for healthcare
insurance coverage for former employees.

                  (d)   CESSATION OF VESTING OF STOCK OPTION. Pursuant to
Section 8 of the Employment Agreement dated as of October 28, 1998 between you
and Calypte (the "EMPLOYMENT AGREEMENT"), that Section 7(d) of your Employment
Agreement, which was amended pursuant to Section 2(d) of your Consulting
Agreement, hereby is further amended to read as follows, effective as of the day
before the Effective Date; except as herein amended, neither your Employment
Agreement nor such options referred to in said section are amended:
<PAGE>


William Boeger
November 14, 2000
Page 3

                  "The Executive may voluntarily terminate his employment at any
         time beginning July 1, 1999, in which event he shall receive severance
         pay equal to six months of his then current salary. If in connection
         with the Executive's voluntary termination of employment hereunder, the
         Executive and the Company enter into a written agreement under which
         the Executive is to render consulting services to the Company, then
         from and after the date of such voluntary termination, vesting
         (exerciseability) of Executive's currently outstanding incentive stock
         option from the Company which was originally granted to Executive on
         October 27, 1998, for a total of 600,000 shares of Common Stock of the
         Company, originally vesting over a 24-month period beginning October
         27, 1998, at the rate of 25,000 shares per month, will not cease and
         such option is hereby amended to provide that it shall continue after
         such termination date to vest (become exerciseable) at the rate of five
         thousand (5,000) shares at the end of each monthly anniversary of the
         date of such termination, through the earlier of the date of
         termination of such consulting agreement or the twelfth (12th) monthly
         anniversary of the date of such termination. Following the twelfth
         (12th) monthly anniversary of the date of such termination, the vesting
         of such option shall cease, even if Executive continues to render
         consulting services. In addition, if in connection with any other
         Calypte stock option plan or grant, other than a plan or grant provided
         to directors of Calypte, Executive has any obligation that requires
         Executive to exercise an option to purchase Calypte stock within a
         specific period of time, such period of time will not begin until the
         date of termination of the Extension to the Consulting Agreement with
         Calypte dated as of October 18, 2000."

         Sections 3 - 6. NO CHANGE These Sections shall remain in effect as set
forth in the Consulting Agreement until the termination of this Extension.

         7.       TERM OF SERVICE; TERMINATION; EFFECT OF TERMINATION.

                  (a)   TERM OF SERVICE; TERMINATION. This Extension is for a
period of twelve (12) months from and after the Effective Date, subject to
earlier termination as provided in Section 7(b) hereof.

                  (b)   NO CHANGE. This Section shall remain in effect as set
forth in the Consulting Agreement until the termination of this Extension.


         Sections 8 & 9. NO CHANGE. These Sections shall remain in effect as
set forth in the Consulting Agreement until the termination of this Extension.


<PAGE>

William Boeger
November 14, 2000
Page 4


         We look forward to continuing to work with you, as a consultant, as
part of our team for the success of Calypte.

                                              Sincerely,

                                              /s/ NANCY KATZ
                                              ----------------------------------
                                              Nancy Katz
                                              President, Chief Executive Officer
                                              and Chief Financial Officer

ACCEPTED AND AGREED:

       /s/ WILLIAM BOEGER
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           William Boeger
Date signed:  November 30, 2000