<PAGE>

     THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
     AMENDED, OR ANY STATE SECURITIES LAWS. IT HAS BEEN ACQUIRED SOLELY FOR
     INVESTMENT AND NOT WITH A VIEW TO, OR IN CONNECTION WITH, THE SALE OR
     DISTRIBUTION THEREOF. THE WARRANT REPRESENTED BY THIS INSTRUMENT MAY NOT
     BE SOLD, TRANSFERRED, OR OTHERWISE DISPOSED OF BY THE HOLDER EXCEPT
     PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT FILED UNDER THE
     SECURITIES ACT OF 1933, AS AMENDED, WITH RESPECT THERETO OR IN
     ACCORDANCE WITH AN OPINION OF COUNSEL IN FORM AND SUBSTANCE SATISFACTORY
     TO THE ISSUER THAN AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE.

No.1                                WARRANT                   September 8, 2000
                  To Purchase 1,000,000 Shares of Common Stock of
                      Prion Developmental Laboratories, Inc.

     1.   NUMBER OF SHARES; EXERCISE PRICE; TERM. This certifies that, in
partial consideration of entering into that certain Investment Agreement
dated September 8, 2000 by and between BioLabs, Inc. ("BioLabs") and Prion
Developmental Laboratories, Inc. (the "Company") and Efoora Inc. and the
additional agreements contemplated therein, BioLabs is entitled, upon the
terms and subject to the conditions hereinafter set forth, at any time after
September 8, 2000 and at or prior to 11:59 p.m. Central Time, on a date which
is eighteen (18) months from the date hereof (the "Expiration Time"), but not
thereafter, to acquire from the Company, in whole or in part, from time to
time, up to 1,000,000 fully paid and nonassessable shares (the "Shares") of
common stock, $.00001 par value, of the Company ("Common Stock") at a
purchase of $.40 per Share. Such number of Shares, type of security and
Exercise Price are subject to adjustment as provided herein, and all
references to "Common Stock" and "Exercise Price" herein shall be deemed to
include any such adjustment or series of adjustments.

     2.   EXERCISE OF WARRANT. The purchase rights exercisable by BioLabs
pursuant to this Warrant shall be exercisable in accordance with paragraphs
2(a) or 2(b) below, as the case may be.

     (a)  CASH EXERCISE. The purchase rights represented by this Warrant are
          exercisable by BioLabs, in whole or in part, at any time, or from
          time to time, subsequent to the date hereof, by the surrender of
          this Warrant and the Notice of Exercise annexed hereto, all duly
          completed and executed on behalf of BioLabs, at the office of the
          Company in Buffalo Grove, Illinois (or such other office or agency
          of the Company as it may designate by notice in writing to BioLabs
          at the address of BioLabs appearing on the books of the Company).
          Payment of the Exercise Price for the Shares thereby purchased
          shall be made by cash, certified or cashier's check or wire
          transfer payable to the order of the Company, at 10:00 a.m.,
          Central Standard Time, on the day following surrender of this
          Warrant and the Notice of Exercise, in an amount equal to the
          purchase price of the Shares thereby purchased. Thereupon, BioLabs
          as the holder of this Warrant, shall be entitled to


                                     - 1 -
<PAGE>

          receive from the Company a stock certificate in proper form
          representing the number of Shares so purchased, and a new Warrant
          in substantially identical form and dated as of such exercise for
          the purchase of that number of Shares equal to the difference, if
          any, between the number of Shares subject hereto and the number of
          Shares as to which this Warrant is so exercised.

     (b)  CASHLESS EXERCISE OF WARRANT. In addition to and without limiting
          the rights of BioLabs under the terms hereof, at BioLabs' option
          this Warrant may be exercised during the term specified above by
          being exchanged in whole or in part prior to its expiration for a
          number of Shares having an aggregate fair market value on the date
          on such exercise equal to the difference between (x) the fair
          market value of the Shares designated as being exercised by BioLabs
          on the date of the exercise and (y) the aggregate Exercise Price
          for such shares in effect at such times. The following diagram
          illustrates how many Shares would then be issued upon exercise
          pursuant to this Section 3:

          Let:        FMV = Fair market value per Share at date of exercise.
                      PSP = Per Share Exercise Price at date of exercise.
                      N   = Number of Shares desired to be exercised.
                      X   = Number of Shares issued after exercise.

          Therefore:  X   = (FMV)(N)A(PSP)(N)
                           -----------------
                                  FMV

Upon any such exercise, the number of Shares purchasable upon exercise of
this Warrant shall be reduced by such designated number of Shares and, if a
balance of purchasable Shares remains after such exercise, the Company shall
execute and deliver to BioLabs a new warrant for such balance of Shares.

     No payment of any cash or other consideration to the Company shall be
required from BioLabs in connection with any exercise of this Warrant by
exchange pursuant to this Section 2(b) or otherwise. Such exchange shall be
effective upon the date of receipt by the Company of the original Warrant
surrendered for cancellation and a written request from BioLabs that the
exchange pursuant to this section be made, or at such later date as may be
specified in such request. No fractional shares arising out of the above
formula for determining the number of shares issuable in such exchange shall
be issued, and the Company shall in lieu thereof make payment to BioLabs of
cash in the amount of such fraction multiplied by the fair market value to a
Share on the date of the exchange.

     If this Warrant expires at any time when the fair market value per Share
is equal to or greater than the Exercise Price, then, in the absence of
notice from BioLabs to the Company indicating otherwise, the Warrant shall be
deemed exercised pursuant to this Section 2(b); provided, that BioLabs shall,
before payment hereunder is made to BioLabs, surrender the original Warrant
for cancellation and submit a written request, dated as of the date of such
deemed exchange, that the exchange pursuant to this Section be made.


                                     - 2 -
<PAGE>

     For the purposes of this Warrant, the "fair market value" of any number
of Shares shall mean:

     (a)  if the Shares are listed on any stock exchange or quotation system,
          the average of the closing price of the Shares on such exchange or
          quotation system for the ten trading days immediately proceeding the
          date of exercise; or

     (b)  if the Shares are not listed on any stock exchange or quotation
          system, the fair market value of the Shares as determined in good
          faith by the board of directors of the Company.

     3.   ISSUANCE OF SHARES. Certificates for Shares purchased hereunder
shall be delivered to BioLabs promptly after the date on which this Warrant
shall have been exercised in accordance with the terms hereof. The Company
hereby represents and warrants that all Shares that may be issued upon the
exercise of this Warrant will, upon such exercise, be duly and validly
authorized and issued, fully paid and nonassessable and free from all taxes,
liens and charges in respect of the issuance thereof (other than liens or
charges created by or imposed upon BioLabs as the holder of the Warrant or
taxes in respect of any transfer occurring contemporaneously or otherwise
specified herein). The Company agrees that the Shares so issued shall be and
shall for all purposes be deemed to have been issued to BioLabs as the record
owner of such Shares as of the close of business on the date on which this
Warrant shall have been exercised or converted in accordance with the terms
hereof.

     4.   NO FRACTIONAL SHARES OR SCRIP. No fractional Shares or scrip
representing fractional Shares shall be issued upon the exercise of this
Warrant. In lieu of any fractional Share to which BioLabs as the holder would
otherwise be entitled, BioLabs shall be entitled, at its option, to receive
either (i) a cash payment equal to the excess of fair market value for such
fractional Share above the Exercise Price for such fractional share (as
determined in good faith by the Company) or (ii) a whole Share if BioLabs
tenders the Exercise Price for one whole share.

     5.   NO RIGHTS AS SHAREHOLDER. This Warrant does not entitle BioLabs as
a holder hereof to any voting rights or other rights as a shareholder of the
Company prior to the exercise hereof.

     6.   CHARGES, TAXES AND EXPENSES. Certificates for Shares issued upon
exercise of this Warrant shall be issued in the name of BioLabs as the holder
of this Warrant. Issuance of certificates for Shares upon the exercise of
this Warrant shall be made without charge to BioLabs for any issue or
transfer tax or other incidental expense in respect of the issuance of such
certificates, all of which taxes and expenses shall be paid by the Company.

     7.   NO TRANSFER. This Warrant and any rights hereunder shall be
assignable and transferable by BioLabs as the holder hereof, in whole or in
part, subject to any applicable securities laws.

     8.   EXCHANGE AND REGISTRY OF WARRANT. This Warrant is exchangeable,
upon the surrender hereof by BioLabs as the registered holder at the
aboveAmentioned office or agency of the Company, for a new Warrant on
substantially identical form and dated as of such exchange.


                                     - 3 -
<PAGE>

The Company shall maintain at the aboveAmentioned office or agency a registry
showing the name and address of BioLabs as the registered holder of this
Warrant. This Warrant may be surrendered for exchange or exercise, in
accordance with its terms, at the office of the Company, and the Company
shall be entitled to rely in all respects, prior to written notice to the
contrary, upon such registry.

     9.   LOSS, THEFT, DESTRUCTION OR MUTILATION OF WARRANT. Upon receipt by
the Company of evidence reasonably satisfactory to it of the loss, theft,
destruction or mutilation of this Warrant, and in the case of loss, theft or
destruction, of indemnity or security reasonably satisfactory to it, and upon
reimbursement to the Company of all reasonable expenses incidental thereto,
and upon surrender and cancellation of this Warrant, if mutilated, the
Company will make and deliver a new Warrant of like tenor and dated as of
such cancellation and reissuance, in lieu of this Warrant.

     10.  RESERVATION OF COMMON STOCK. The Company will at all times reserve
and keep available, solely for issuance, sale and delivery upon the exercise
of this Warrant, such number of Shares, equal to the number of such Shares
purchasable upon the exercise of this Warrant. All such Shares shall be duly
authorized and, when issued upon exercise of this Warrant in accordance with
the terms hereof, will be validly issued and fully paid and nonassessable,
with no liability on the part of BioLabs. Such Shares will not be subject to
any preemptive rights.

     11.  LISTING ON SECURITIES EXCHANGES, ETC. The Company will maintain the
listing of all Shares issuable or issued from time to time upon exercise of
this Warrant on each securities exchange or market or trading system on which
any shares of Common Stock are then or at any time thereafter listed or
traded, if any, but only to the extent and for such period of time as such
shares of Common Stock are so listed.

     12.  SATURDAYS, SUNDAYS, HOLIDAYS, ETC. If the last or appointed day for
the taking of any action or the expiration of any right required or granted
herein shall be a Saturday or a Sunday or shall be a legal holiday, then such
action may be taken or such right may be exercised on the next succeeding day
not a Saturday or a Sunday or a legal holiday.

     13.  ADJUSTMENTS.

          (a)  Subdivision or Combination of Shares. In the event of a stock
               split, reverse stock split, stock dividend, reorganization or
               recapitalization affecting the number of shares of Common Stock
               outstanding, the Exercise Price of the Shares shall be
               proportionately revised so as to fairly and equitably preserve
               the conversion rights of the Warrant, as follows.

               (i)    (A) If the Company shall issue, after the date hereof,
                          any Additional Stock (as defined below) without
                          consideration or for a consideration per share less
                          than the Exercise Price in effect immediately prior
                          to the issuance of such Additional Stock, such
                          Exercise Price shall forthwith be adjusted to a
                          price equal to the consideration per share at which
                          such shares of Additional Stock were so issued.


                                     - 4 -
<PAGE>

                      (B) If the Company shall issue any Additional Stock
                          without consideration or for a consideration per
                          share less than the Exercise Price in effect
                          immediately prior to the issuance of such Additional
                          Stock, such Exercise Price shall forthwith (except as
                          otherwise provided in this clause (i)) be adjusted to
                          a price equal to the quotient obtained by dividing
                          the total computed under clause (x) below by the
                          total computed under clause (y) below as follows:

                          (x) an amount equal to the sum of:

                              (1) the aggregate purchase price of the Shares,
                                  plus;

                              (2) the aggregate consideration, if any,
                                  received by the Company for all Additional
                                  Stock issued on or after the date hereof;

                          (y) an amount equal to the sum of:

                              (1) the aggregate purchase price of the Shares
                                  divided by the Exercise Price in effect on
                                  the date hereof (or such higher or lower
                                  Exercise Price as results from the
                                  application of subsections (iii) and (iv));

                              (2) the number of shares of Additional Stock
                                  issued since the date hereof (increased or
                                  decreased to the extent that the number of
                                  such shares of Additional Stock shall have
                                  been increased or decreased as the result
                                  of the application of subsections (iii)
                                  and (iv));

                          provided, however, that the foregoing calculation
                          shall not take into account shares deemed issued
                          pursuant to subsection (i)(F) on account of
                          options, rights or convertible or exchangeable
                          securities (or the actual or deemed consideration
                          therefor), except to the extent (i) such options,
                          rights or convertible securities have been
                          exercised or converted, or (ii) the consideration
                          to be paid upon such exercise, conversion or
                          exchange per share of underlying Common Stock is
                          less than or equal to the per share consideration
                          for the Additional Stock which has given rise to
                          the Exercise Price adjustment being calculated.

                      (C) No adjustment of the Exercise Price shall be made
                          in an amount less than one cent per share;
                          provided, that any adjustments which are not
                          required to be made by reason of this sentence
                          shall be carried forward and shall be either taken
                          into account in any subsequent adjustment made
                          prior to three (3) years from the date of the event
                          giving rise to the adjustment being carried
                          forward, or

                                     - 5 -
<PAGE>

                          shall be made at the end of three (3) years from
                          the date of the event giving rise to the adjustment
                          being carried forward. Except to the limited extent
                          provided for in subsections (F)(3) and (F)(4), no
                          adjustment of the Exercise Price pursuant to this
                          subsection (i) shall have the effect of increasing
                          the Exercise Price above the Exercise Price in
                          effect immediately prior to such adjustment.

                      (D) In the case of the issuance of Common Stock for
                          cash, the consideration shall be deemed to be the
                          amount of cash paid therefor before deducting any
                          reasonable discounts, commissions or other expenses
                          allowed, paid or incurred by the Company for any
                          underwriting or otherwise in connection with the
                          issuance and sale thereof.

                      (E) In the case of the issuance of the Common Stock for
                          a consideration in whole or in part other than
                          cash, the consideration other than cash shall be
                          deemed to be the fair value thereof as reasonably
                          determined by the Board of Directors in good faith
                          irrespective of any accounting treatment.

                      (F) In the case of the issuance (whether before, on or
                          after the commencement date) of options to purchase
                          or rights to subscribe for Common Stock, securities
                          by their terms convertible into or exchangeable for
                          Common Stock or options to purchase or rights to
                          subscribe for such convertible or exchangeable
                          securities, the following provisions shall apply
                          for all purposes of subsections (i) and (ii):

                          1. The aggregate maximum number of shares of Common
                             Stock deliverable upon exercise (assuming the
                             satisfaction of any conditions to
                             exercisability, including without limitation,
                             the passage of time, but without taking into
                             account potential antidilution adjustments) of
                             such options to purchase or rights to subscribe
                             for Common Stock shall be deemed to have been
                             issued at the time such options or rights were
                             issued and for a consideration equal to the
                             consideration (determined in the manner provided
                             in subsections (i)(D) and (i)(E)), if any,
                             received by the Company upon the issuance of
                             such options or rights plus the minimum exercise
                             price provided in such options or rights
                             (without taking into account potential
                             antidilution adjustments) for the Common Stock
                             covered thereby.

                          2. The aggregate maximum number of shares of Common
                             Stock deliverable upon conversion of or in
                             exchange (assuming the satisfaction of any
                             conditions to convertibility or exchangeability,
                             including, without


                                     - 6 -
<PAGE>

                             limitation, the passage of time, but without
                             taking into account potential antidilution
                             adjustments) for any such convertible or
                             exchangeable securities or upon the exercise of
                             options to purchase or rights to subscribe for
                             such convertible or exchangeable securities and
                             subsequent conversion or exchange thereof shall
                             be deemed to have been issued at the time such
                             securities were issued or such options or rights
                             were issued and for a consideration equal to the
                             consideration, if any, received by the Company
                             for any such securities and related options or
                             rights (excluding any cash received on account
                             of accrued interest or accrued dividends), plus
                             the minimum additional consideration, if any, to
                             be received by the Company (without taking into
                             account potential antidilution adjustments) upon
                             the conversion or exchange of such securities or
                             the exercise of any related options or rights
                             (the consideration in each case to be determined
                             in the manner provided in subsections (i)(D) and
                             (i)(E)).

                          3. In the event of any change in the number of
                             shares of Common Stock deliverable or in the
                             consideration payable to the Company upon
                             exercise of such options or rights or upon
                             conversion of or in exchange for such
                             convertible or exchangeable securities,
                             including, but not limited to, a change
                             resulting from the antidilution provisions
                             thereof, the Exercise Price, to the extent in
                             any way affected by or computed using such
                             options, rights or securities, shall be
                             recomputed to reflect such change, but no
                             further adjustment shall be made for the actual
                             issuance of Common Stock or any payment of such
                             consideration upon the exercise of any such
                             options or rights or the conversion or exchange
                             of such securities.

                          4. Upon the expiration of any such option or
                             rights, the termination of any such rights to
                             convert or exchange or the expiration of any
                             options or rights related to such convertible or
                             exchangeable securities, the Exercise Price, to
                             the extent in any way affected by or computed
                             using such options, rights or securities or
                             options or rights related to such securities,
                             shall be recomputed to reflect the issuance of
                             only the number of shares of Common Stock (and
                             convertible or exchangeable securities which
                             remain in effect) actually issued upon the
                             exercise of such options or rights, upon the
                             conversion or exchange of such securities or
                             upon the exercise of the options or rights
                             related to such securities.


                                     - 7 -
<PAGE>

                          5. The number of shares of Common Stock deemed
                             issued and the consideration deemed paid
                             therefor pursuant to subsections (i)(F)(1) and
                             (2) shall be appropriately adjusted to reflect
                             any change, termination or expiration of the
                             type described in either subsection (i)(F)(3) or
                             (4).

               (ii)   "Additional Stock" shall mean any shares of Common Stock
                      issued (or deemed to have been issued pursuant to
                      subsection (i)(F)) by the Company after the commencement
                      date other than:

                      (A) Common Stock issued pursuant to a transaction
                          described in subsection (iii) hereof;

                      (B) Shares of Common Stock issuable or issued to
                          officers, directors, employees, consultants,
                          vendors, or other persons with important business
                          relationships with, the Company directly or
                          pursuant to a stock option plan, or restricted
                          stock plan, a stock purchase agreement or similar
                          plan or arrangement approved by the Board of
                          Directors of the Company; provided, however, the
                          issuance of such shares shall be in an amount not
                          to exceed ten percent (10%) of the Common Stock of
                          the Company outstanding from time to time, on a
                          Fully Diluted Basis;

                      (C) the Warrant, any other Warrant issued to BioLabs,
                          or the Shares;

                      (D) shares of Common Stock issued as a dividend or
                          distribution on the Warrants or the Shares; or

                      (E) shares of Common Stock issued as consideration in a
                          merger or acquisition for which the vote of BioLabs
                          is obtained.

               (iii)  In the event the Company should at any time or from
                      time to time after the date hereof fix a record date
                      for the effectuation of a split or subdivision of the
                      outstanding shares of Common Stock or the determination
                      of holders of Common Stock entitled to receive a
                      dividend or other distribution payable in additional
                      shares of Common Stock or other securities or rights
                      convertible into, or entitling BioLabs thereof to
                      receive directly or indirectly, additional shares of
                      Common Stock (hereinafter referred to as "Common Stock
                      Equivalents") without payment of any consideration by
                      such holder for the additional shares of Common Stock
                      or the Common Stock Equivalents (including the
                      additional shares of Common Stock issuable upon
                      conversion or exercise thereof), then, as of such
                      record date (or the date of such dividend distribution,
                      split or subdivision if no record date is fixed), the
                      Exercise Price shall be appropriately decreased so that


                                     - 8 -
<PAGE>

                      the number of Warrant Shares issuable on exercise of
                      the Warrant shall be increased in proportion to such
                      increase of the aggregate number of shares of Common
                      Stock outstanding and those issuable with respect to
                      Common Stock Equivalents, with the number of shares
                      issuable with respect to Common Stock Equivalents
                      determined from time to time in the manner provided for
                      deemed issuances in subsection (i)(F).

               (iv)   If the number of shares of Common Stock outstanding at
                      any time after the date hereof is decreased by a
                      combination of the outstanding shares of Common Stock,
                      then, following the record date of such combination (or
                      the date of such decrease in the outstanding shares of
                      Common Stock if no record date is fixed), the Exercise
                      Price, as the case may be, shall be appropriately
                      increased so that the number of shares of Common Stock
                      issuable on exercise of the Warrant shall be decreased
                      in proportion to such decrease in outstanding shares.

          (b)  OTHER DISTRIBUTIONS. In the event the Company shall declare a
               dividend or distribution payable in securities of other
               persons, evidences of indebtedness issued by the Company or
               other persons, assets (excluding cash dividends) or options or
               rights not referred to in subsection (a)(iii), then, in each
               such case for the purpose of this subsection (b), BioLabs
               shall be entitled to a proportionate share of any such
               distribution as though he were BioLabs of the number of shares
               of Common Stock of the Company into which the Warrant is
               convertible as of the record date fixed for the determination
               of BioLabs of Common Stock of the Company entitled to receive
               such dividend or distribution (or the date of such
               distribution if no record date is fixed).

          (c)  RECAPITALIZATIONS. If, at any time or from time to time, there
               shall be a recapitalization of the Common Stock (other than a
               subdivision, combination or merger or sale of assets
               transaction provided for elsewhere in this Section 5),
               provision shall be made so that BioLabs shall thereafter be
               entitled to receive upon exercise of the Warrant the number of
               shares of stock or other securities or property of the Company
               or otherwise, to which a holder of Common Stock deliverable
               upon exercise would have been entitled on such
               recapitalization. In any such case, appropriate adjustment
               shall be made in the application of the provisions of this
               Section 5 with respect to the rights of BioLabs after the
               recapitalization to the end that the provisions of this
               Section 5 (including adjustment of the Exercise Price then in
               effect and the number of shares purchasable upon exercise of
               the Warrant) shall be applicable after that event as nearly
               equivalent as may be practicable.

          (d)  NO IMPAIRMENT. The Company will not, by amendment of its
               charter or through any reorganization, recapitalization,
               transfer of assets, consolidation, merger, dissolution, issue
               or sale of securities or any other voluntary action, avoid or
               seek to avoid the observance or performance of any of the
               terms to be observed or performed hereunder by the Company,
               but will at all times in good faith assist in the carrying out
               of all the provisions of this Section 5 and in the taking of
               all such


                                     - 9 -
<PAGE>

               action as may be necessary or appropriate in order to protect
               the conversion rights of BioLabs against impairment.

          (e)  CERTIFICATES AS TO ADJUSTMENTS.

               (i) Upon the occurrence of each adjustment or readjustment of
                   the Exercise Price pursuant to this Section 5, the
                   Company, at its expense, shall promptly compute such
                   adjustment or readjustment in accordance with the terms
                   hereof and prepare and furnish to BioLabs a certificate
                   setting forth such adjustment or readjustment and showing
                   in detail the facts upon which such adjustment or
                   readjustment is based. The Company shall, upon the written
                   request at any time of BioLabs, furnish or cause to be
                   furnished to Holder a like certificate setting forth (A)
                   such adjustment and readjustment, (B) the Exercise Price
                   at the time in effect, and (C) the number of Shares and
                   the amount, if any, of other property which at the time
                   would be received upon the conversion of the Warrant.

          (f)  NOTICE OF RECORD DATE. In the event of any taking by the
               Company of a record of BioLabs of any class of securities for
               the purpose of determining BioLabs thereof who are entitled to
               receive any dividend (other than a cash dividend) or other
               distribution, any right to subscribe for, purchase or
               otherwise acquire any shares of stock of any class or any
               other securities or property, or to receive any other right,
               the Company shall mail to BioLabs, at least twenty (20) days
               prior to the date specified therein, a notice specifying the
               date on which any such record is to be taken for the purpose
               of such dividend, distribution or right and the amount and
               character of such dividend, distribution or right.

     14.  NOTICE OF ADJUSTMENTS; NOTICES. Whenever the Exercise Price or
number or type of securities issuable hereunder shall be adjusted pursuant to
Section 13 hereof, the Company shall issue and provide to BioLabs as the
holder of this Warrant a certificate signed by an officer of the Company
setting forth, in reasonable detail, the event requiring the adjustment, the
amount of the adjustment, the method by which such adjustment was calculated
and the Exercise Price and number of Shares purchasable hereunder after
giving effect to such adjustment.

     15.  GOVERNING LAW. This Warrant shall be binding upon any successors or
assigns of the Company. This Warrant shall constitute a contract under the
laws of Illinois and for all purposes shall be construed in accordance with
and governed by the laws of said state, without giving effect to the conflict
of laws principles.

     16.  AMENDMENTS. This Warrant may be amended and the observance of any
term of this Warrant may be waived only with the written consent of the
Company and BioLabs as the holder hereof.

     17.  NOTICE. All notices hereunder shall be in writing and shall be
effective (a) on the day on which delivered if delivered personally or
transmitted by telex or telegram or telecopier with evidence of receipt, (b)
one (1) business day after the date on which the same is delivered to a
nationally recognized overnight courier service with evidence of receipt, or
(c) five (5) business


                                     - 10 -
<PAGE>

days after the date on which the same is deposited, postage prepaid, in the
U.S. mail, sent by certified or registered mail, return receipt requested,
and addressed to the party to be notified at the address indicated below for
the Company, or at the address for BioLabs as the holder set forth in the
registry maintained by the Company pursuant to Section 8, or at such other
address and/or telecopy or telex number and/or to the attention of such other
person as the Company or BioLabs as the holder may designate by ten (10) day
advance written notice.

     18.  ENTIRE AGREEMENT. This Warrant and the forms attached hereto
contain the entire agreement between the parties with respect to the subject
matter hereof and supersede all prior and contemporaneous arrangements or
undertakings with respect thereto.

     IN WITNESS WHEREOF, Prion Developmental Laboratories, Inc. has caused
this Warrant to be executed by its duly authorized officer.

Dated: September 8, 2000          PRION DEVELOPMENTAL LABORATORIES, INC.

                                  By: /s/ DAVID S. GROSKY
                                      ______________________________________

                                  Name: ____________________________________

                                  Title: ___________________________________


                                  Address: 1000 Asbury Drive, Suite 7
                                           Buffalo Grove, IL 60089


                                     - 11 -