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                                                                    EXHIBIT 10.4

                              EMPLOYMENT AGREEMENT


                              ANTEX BIOLOGICS INC.



        THIS EMPLOYMENT AGREEMENT (the "Agreement"), made as of May 1, 1998 is
entered into by Antex Biologics Inc., a Delaware corporation with its principal
place of business at 300 Professional Drive, Gaithersburg, Maryland 20879 (the
"Company"), and Gregory C. Zakarian, residing at 6633 Shalestone Court, Clifton,
Virginia 20124 (the "Employee").

                                   WITNESSETH:

        WHEREAS, the Company desires to employ the Employee, and the Employee
desires to be employed by the Company;

        NOW THEREFORE, in consideration of the mutual covenants and promises
contained herein, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged by the parties hereto, the parties
agree as follows:

        1.   Term of Employment. The Company hereby agrees to employ the
Employee, and the Employee hereby accepts employment with the Company, upon the
terms set forth in this Agreement, for the period commencing on May 1, 1998 (the
"Commencement Date") and ending on April 30, 2001 (such period, as it may be
extended, the "Employment Period"), unless sooner terminated in accordance with
the provisions of Section 4 hereof. Upon the third anniversary of the
Commencement Date and upon every third anniversary of the Commencement Date
thereafter, the term of the Employment Period shall be extended automatically
for three (3) additional years unless, at least twelve (12) months prior to such
anniversary, the Company shall have delivered to the Employee or, at least six
(6) months prior to such anniversary, the Employee shall have delivered to the
Company, written notice that the term of the Employee's employment hereunder
will not be extended.

        2.   Title; Capacity. The Employee shall serve as Vice President and
Chief Financial Officer or in such other position as the Company or its Board of
Directors (the "Board") may determine from time to time. The Employee shall be
based at the Company's headquarters in Gaithersburg, Maryland, or such place or
places in the continental United States as the Board shall determine and is
reasonable and acceptable to the Employee. The Employee shall be subject to the
supervision of, and shall have such authority as is delegated to him by, the
Board or such officer of the Company as may be designated by the Board.

        The Employee hereby accepts such employment and agrees to undertake the
duties and responsibilities inherent in such position and such other duties and
responsibilities as


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the Board or its designee shall from time to time reasonably assign to him. The
Employee agrees to devote his entire business time, attention and energies to
the business and interests of the Company during the Employment Period. He shall
not engage in any other business activity, except as may be approved by the
Company which approval shall not be unreasonably withheld. The Employee agrees
to abide by the rules, regulations, instructions, personnel practices and
policies of the Company and any changes therein which may be adopted from time
to time by the Company. The Employee acknowledges receipt of copies of all such
rules and policies committed to writing as of the date of this Agreement.

        3.    Compensation and Benefits.

              3.1 Salary. The Company shall pay the Employee, in semi-monthly
installments on the 15th and month-end or on the last working day of such month,
an annual base salary (the "Annual Base Salary") of One Hundred Fifty Thousand
Dollars ($150,000) for the period commencing on the Commencement Date.
Thereafter, upon each anniversary of the Commencement Date (including the first
anniversary thereof), following an annual review by the Board, the Board may
adjust the Employee's Annual Base Salary as it determines in its sole
discretion; provided, however, that the Board of Directors shall not reduce the
Annual Base Salary.

              3.2 Fringe Benefits. The Employee shall be entitled to
participate in all bonus, stock option, benefit and insurance programs that the
Company establishes and makes available to its employees, if any, to the extent
that Employee's position, tenure, salary, age, health and other qualifications
make him eligible to participate. The Employee shall be entitled to twenty (20)
days paid vacation per year, to be taken at such times as may be approved by the
Board or its designee.

              3.3 Reimbursement of Expenses. The Company shall reimburse the
Employee for all reasonable travel, entertainment and other expenses incurred or
paid by the Employee in connection with, or related to, the performance of his
duties, responsibilities or services under this Agreement, upon presentation by
the Employee of documentation, expense statements, vouchers and/or such other
supporting information as the Company may request; provided, however, that the
amount available for such travel, entertainment and other expenses may be fixed
in advance by the Board.

              3.4 Bonus. The Employer shall, subject to approval of the Board,
pay to the Employee an appropriate bonus (the "Bonus") with respect to each
completed year of employment. The Bonus shall be paid to Employee in one lump
sum on or prior to January 31 of each year for the one-year period of
employment, or portion thereof, ending on the preceding December 31.

        4.    Employment Termination. The employment of the Employee by the
Company pursuant to this Agreement shall terminate upon the occurrence of any of
the following:

              4.1 Expiration of the Employment Period in accordance with
Section 1 hereof and if the term is not extended in accordance with Section 1
hereof, then the provisions of Section 4.4 hereof shall apply;



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              4.2 At the election of the Company, for cause, immediately upon
written notice by the Company to the Employee. For the purposes of this Section
4.2, cause for termination shall be deemed to exist upon (a) a good faith
finding by the Company of failure of the Employee to perform his assigned duties
for the Company, dishonesty, gross negligence or misconduct, or (b) the
conviction of the Employee of, or the entry of a pleading of guilty or nolo
contendere by the Employee to, any crime involving moral turpitude or any
felony;

              4.3 Upon the death or ninety (90) days after the disability of the
Employee. As used in this Agreement, the term "disability" shall mean the
inability of the Employee, due to a physical or mental disability, for a period
of ninety (90) days, whether or not consecutive, during any three hundred sixty
(360)-day period to perform the services contemplated under this Agreement. A
determination of disability shall be made by a physician satisfactory to both
the Employee and the Company, provided that if the Employee and the Company do
not agree on a physician, the Employee and the Company shall each select a
physician and these two together shall select a third physician, whose
determination as to disability shall be binding on all parties;

              4.4 At the election of the Company, upon not less than twelve (12)
months' prior written notice of termination to the Employee. At the option of
the Company and in lieu of such notice, the Company may pay to Employee an
amount equal to (i) twelve (12) months' salary computed on the basis of the then
current Annual Base Salary plus (ii) any bonus to which Employee is entitled. If
the Company elects to pay such amount in lieu of notice it shall, at the expense
of the Company, continue Employee's participation in all benefits programs
including but not limited to medical, dental and life insurance programs
provided by the Company to the Employee under Section 3.2 hereof on the date on
which such amount is paid (the "Payment Date") until a date twelve (12) months
after the Payment Date. In the event Employee's termination is related to a
"change of control" and occurs within one (1) year of such change of control the
notice or salary in lieu of notice and participation in the benefits program
will be for twelve (12) months. In the event that Employee commences employment
or self-employment during the period the Company is making payments as a result
of a change of control then the salary payment maybe reduced by the amount the
Employee receives through employment or self-employment and the benefits will
terminate on the date Employee becomes eligible to participate in the benefits
program pursuant to employment or self-employment. The exercise of stock options
and any modifications to the exercise period will be in accordance with the
Company's Amended and Restated Stock Option Plan.

              4.5 At the election of the Employee, upon not less than six (6)
months prior written notice of termination to the Company.

        5.    Effect of Termination.

              5.1 Termination for Cause or at Election of Either Party. In the
event the Employee's employment is terminated for cause pursuant to Section 4.2
hereof, or at the election of the Employee pursuant to Section 4.5 hereof, the
Company shall pay to the Employee the compensation and benefits otherwise
payable to him under Section 3 hereof through the last day of his actual
employment by the Company.


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              5.2 Termination for Death or Disability. If the Employee's
employment is terminated by death or because of disability pursuant to Section
4.3 hereof, the Company shall pay to the estate of the Employee or to the
Employee, as the case may be, the compensation which would otherwise be payable
to the Employee up to the end of the month in which the termination of his
employment because of death or disability occurs.

              5.3 Survival. The provisions of Sections 6 and 7 hereof shall
survive the termination of this Agreement.

        6.    Non-Competition.

              (a)   During the Employment Period and for a period of two (2)
years after the termination or expiration thereof, the Employee will not
directly or indirectly:

              (i)   as an individual proprietor, partner, stockholder, officer,
                    employee, director, joint venturer, investor, lender, or in
                    any other capacity whatsoever (other than as the holder of
                    not more than one percent (1%) of the total outstanding sock
                    of a publicly held company), engage in the business of
                    developing, producing, marketing or selling products of the
                    kind or type developed or being developed, produced,
                    marketed or sold by the Company while the Employee was
                    employed by the Company; or

              (ii)  recruit, solicit, or induce, or attempt to induce, any
                    employee or employees of the Company to terminate their
                    employment with, or otherwise cease their relationship with,
                    the Company; or

              (iii)     solicit, divert or take away, or attempt to divert or to
                        take away, the business or patronage of any of the 
                        clients, customers or accounts, or prospective clients,
                        customers or accounts, of the Company which were 
                        contacted, solicited or served by the Employee while 
                        employed by the Company.

              (b)   If any restriction set forth in this Section 6 is found by
any court of competent jurisdiction to be unenforceable because it extends for
too long a period of time or over too great a range of activities or in too
broad a geographic area, it shall be interpreted to extend only over the maximum
period of time, range of activities or geographic area as to which it may be
enforceable.

              (c)   The restrictions contained in this Section 6 are necessary
for the protection of the business and goodwill of the Company and are
considered by the Employee to be reasonable for such purpose. The Employee
agrees that any breach of this Section 6 will cause the Company substantial and
irrevocable damage and therefore, in the event of any such breach, in addition
to such other remedies which may be available, the Company shall have the right
to seek specific performance and injunctive relief.

        7.    Proprietary Information and Development.

              7.1 Proprietary Information.


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              (a)  Employee agrees that all information and know-how, whether or
not in writing, or a private, secret or confidential nature concerning the
Company's business or financial affairs (collectively, "Proprietary
Information") is and shall be the exclusive property of the Company. By way of
illustration, but not limitation, Proprietary Information may include
inventions, products, processes, methods, techniques, formulas, compositions,
compounds, projects, developments, plans, research data, clinical data,
financial data, personnel data, computer programs, and customer and supplier
lists. Employee will not disclose any Proprietary Information to others outside
the Company or use the same for any unauthorized purposes without written
approval by an officer of the Company, either during or after his employment,
unless and until such Proprietary Information has become public knowledge
without fault by the Employee.

              (b)  Employee agrees that all files, letters, memoranda, reports,
records, data, sketches, drawings, laboratory notebooks, program listings, or
other written, photographic, or other tangible material containing Proprietary
Information, whether created by the Employee or others, which shall come into
his custody or possession, shall be and are the exclusive property of the
Company to be used by the Employee only in the performance of his duties for the
Company.

              (c)  Employee agrees that his obligation not to disclose or use
information, know-how and records of the types set forth in paragraphs (a) and
(b) above, also extends to such types of information, know-how, records and
tangible property of customers of the Company or suppliers to the Company or
other third parties who may have disclosed or entrusted the same to the Company
or to the Employee in the course of the Company's business.

              7.2  Developments.

              (a)  Employee will make full and prompt disclosure to the Company
of all inventions, improvements, discoveries, methods, developments, software,
and works of authorship, whether patentable or not, which are created, made,
conceived or reduced to practice by the Employee or under his direction or
jointly with others during his employment by the Company, whether or not during
normal working hours or on the premises of the Company (all of which are
collectively referred to in this Agreement as "Developments").

              (b)  Employee agrees to assign and does hereby assign to the
Company (or any person or entity designated by the Company) all his right,
title and interest in and to all Developments and all related patents, patent
applications, copyrights and copyright applications. However, this Section 7.2
(b) shall not apply to Developments which do not related to the present or
planned business or research and development of the Company and which are made
and conceived by the Employee not during normal working hours, not on the
Company's premises and not using the Company's tools, devices, equipment or
Proprietary Information.

              (c)  Employee agrees to cooperate fully with the Company, both
during and after his employment with the Company, with respect to the
procurement, maintenance and enforcement of copyrights and patents (both in the
United States and foreign countries) relating to Developments. Employee shall
sign all papers, including, without limitation,


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copyright applications, patent applications, declarations, oaths, formal
assignments, assignment of priority rights, and powers of attorney, which the
Company may deem necessary or desirable in order to protect its rights and
interests in any Development.

              7.3  Other Agreements. Employee hereby represents that he is not
bound by the terms of any agreement with any previous employer or other party to
refrain from using or disclosing any trade secret or confidential or proprietary
information in the course of his employment with the Company or to refrain from
competing, directly or indirectly, with the business of such previous employer
or any other party. Employee further represents that his performance of all
terms of this Agreement and as an employee of the Company does not and will not
breach any agreement to keep in confidence proprietary information, knowledge or
data acquired by him in confidence or in trust prior to his employment with the
Company.

        8.    Prior Agreements. This Agreement supersedes an Employment
Agreement dated as of May 1, 1995 by and between the Employer and Employee (the
"Prior Agreement") and, as of the date hereof, the Prior Agreement shall be of
no further force and effect.

        9.    Notices. All notices required or permitted under this Agreement
shall be in writing and shall be deemed effective upon personal delivery or upon
deposit in the United States Post Office, by registered or certified mail,
postage prepaid, addressed to the other party at the address shown above, or at
such other address or addresses as either party shall designate to the other in
accordance with this Section 9.

        10.   Pronouns. Whenever the context may require, any pronouns used in
this Agreement shall include the corresponding masculine, feminine or neuter
forms, and the singular forms of nouns and pronouns shall include the plural,
and vice versa.

        11.   Entire Agreement. This Agreement constitutes the entire agreement
between the parties and supersedes all prior agreements and understandings,
whether written or oral, relating to the subject matter of this Agreement.

        12.   Amendment. This Agreement may be amended or modified only by a
written instrument executed by both the Company and the Employee.

        13.   Governing Law. This Agreement shall be construed, interpreted and
enforced in accordance with the laws of the State of Maryland.

        14.   Successors and Assigns. This Agreement shall be binding upon and
inure to the benefit of both parties and their respective successors and
assigns, including any corporation with which or into which the Company may be
merged to which may succeed to its assets or business, provided, however, that
the obligations of the Employee are personal and shall not be assigned by him.


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        15.   Miscellaneous.

              15.1  No delay or omission by the Company in exercising any right
under this Agreement shall operate as a waiver of that or any other right. A
waiver or consent given by the Company on any one occasion shall be effective
only in that instance and shall not be construed as a bar or waiver of any right
on any other occasion.

              15.2  The captions of the sections of this Agreement are for
convenience of reference only and in no way define, limit of affect the scope or
substance of any section of this Agreement.

              15.3  In case any provision of this Agreement shall be invalid,
illegal or otherwise unenforceable, the validity, legality and enforceability of
the remaining provisions shall in no way be affected or impaired thereby.

        IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the day and year set forth above.

                                      ANTEX BIOLOGICS INC.


                                      by     /s/V. M. Esposito, Ph.D.
                                           -------------------------------------
                                              V. M. Esposito, Ph.D.
                                              President and CEO
                                              Chairman of the Board of Directors


                                      Employee


                                             /s/Gregory C. Zakarian
                                           -------------------------------------
                                              Gregory C. Zakarian