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Exhibit 10.318

***Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

CERTAIN MATERIAL (INDICATED BY AN ASTERISK) HAS BEEN OMITTED FROM THIS DOCUMENT
PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT. THE OMITTED MATERIAL HAS BEEN
FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

AMENDMENT NO. 3 TO
AGREEMENT

        This Amendment No. 3 ("Amendment No. 3") is entered effective April 1,
2002 (the "Amendment Effective Date") pursuant to and amending that certain
Agreement (as defined below) between Gen-Probe Incorporated, a Delaware
corporation ("Gen-Probe") and Chiron Corporation, a Delaware corporation
("Chiron"), on behalf of itself and its Affiliates. Capitalized terms used but
not defined herein shall have the meanings set forth in the Agreement.

Recitals

        A. The parties entered into the Agreement as of June 11, 1998 pursuant
to which, among other things, the parties described their respective rights and
obligations with respect to production planning and inventory management
processes. The Agreement was amended by the following: (i) June 11, 1998
Collaboration Agreement, (ii) June 11, 1998 Supplemental letter agreement,
(iii) June 26, 1998 Addendum to Collaboration Agreement, (iv) June 30, 1998
Supplemental letter agreement, (v) June 30, 1998 Consent, (vi) December 1, 1998
letter agreement re American Red Cross revenues, (vii) December 7, 1999 First
amendment to Collaboration Agreement, (viii) February 1, 2000 Second amendment
to Collaboration Agreement, (ix) June 7, 2001 Supplemental agreement no. 1
(Customer training and Support), (x) October 30, 2001 Confidentiality and Joint
Interest Agreement, (xi) April 4, 2001 Agreement re Arbitration. In addition,
the parties entered into that certain Definitive Written Settlement Agreement
dated December 4, 2001 (the "Settlement Agreement").

        B. The parties have discussed a proposed revision to and clarification
of their respective rights and obligations with respect to production planning
and inventory management processes, and have agreed to make certain additional
changes to the Agreement in connection therewith, in accordance with the
provisions of this Amendment No. 3.

        C. By this Amendment No. 3, the parties desire to revise and clarify
their respective rights and obligations, as described herein, applicable to all
Blood Screening Assays, including one or more Future Blood Screening Assays to
be conducted by the Blood Screening Instruments to be developed under the terms
of the Agreement.

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Agreement

        NOW, THEREFORE, for and in consideration of the mutual covenants and
agreements set forth in this Amendment No. 3, the parties agree as follows:

        1.    Definitions.    

        1.1  "Agreement" means that certain Agreement entered into as of
June 11, 1998 by and between Gen-Probe Incorporated, a Delaware corporation with
a principal place of business at 10210 Genetic Center Drive, San Diego CA 92121
and Chiron Corporation, a Delaware corporation, with a place of business at 4560
Horton Street, Emeryville, CA 94608, on behalf of itself and its Affiliates, as
amended by the amendments referenced in Recital A above.

        1.2  "Settlement Agreement" means that certain Definitive Written
Settlement Agreement dated December 5, 2001 executed by and between Chiron
Corporation and Gen-Probe Incorporated.

        1.3  "Supplemental Agreement" means that certain Supplemental Agreement
No. 2 dated December 5, 2001 executed by and between Chiron Corporation and
Gen-Probe Incorporated.

        1.4    The following definitions shall be added to the Agreement, for
the purpose of the amendments made by this Amendment No. 3, by adding the
following subsections to Section 1 of the Agreement:

        "1.60  "Customer" means the Third Party to whom Blood Screening Assays
are sold, transferred or otherwise conveyed by Chiron, its Affiliates or the
Major Distributor.

        1.61 "Forecast" means the twelve-month rolling forecast of Chiron's
estimated purchase requirements of Blood Screening Assays over the period
covered by the forecast, as set forth in Section 6.3.1 of the Agreement, as
amended pursuant to this Amendment No. 3.

        1.62 "Lot" means each of Gen-Probe's manufacturing lots of Blood
Screening Assays.

        1.63 "Purchase Order" means the binding purchase order of Blood
Screening Assays delivered in accordance with the provisions of Section 6.3.3 of
the Agreement, as amended pursuant to this Amendment No. 3."

        2.    Forecasts And Orders.    Section 6.3 of the Agreement and its
associated subsections are hereby deleted and replaced in their entirety with
the following:

        "6.3 Forecasts and Orders.

        6.3.1    Forecasts.

        (a)  On or before the first (1st) day of each calendar month during the
term of this Agreement, Chiron shall provide to Gen-Probe a Forecast, covering
the period commencing the calendar month immediately succeeding the month in
which the Forecast is delivered (for example, on January 1, Chiron will deliver
a rolling twelve (12) month Forecast commencing February 1), showing Chiron's
estimated purchase requirements over the period covered by the Forecast. The
Forecast shall include purchase requirements, at the following level of detail:

        (i)    for the first (1st), second (2nd) and third (3rd) calendar months
covered by the Forecast, the Forecast shall specify the Blood Screening Assays
by packaging configuration, including kit size and/or catalogue part number, and
associated quantities for purchase from Gen-Probe by Chiron in such three-month
period;

        (ii)    for the fourth (4th), fifth (5th) and sixth (6th) calendar
months covered by the Forecast, the Forecast shall specify the Blood Screening
Assays and ancillary

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materials, by labeling requirement detailed according to the provisions of
Schedule A.1, attached hereto, and associated quantities that Chiron expects to
order from Gen-Probe by Chiron in such period; and

        (iii)    for the seventh (7th) through twelfth (12th) calendar months
covered by the Forecast, the Forecast shall specify the estimated purchase
requirements, by test, and associated quantities that Chiron expects to order
from Gen-Probe by Chiron in such period.

        (iv)    Subject to the additional provisions set forth in subparagraph
(v) below, in each Forecast delivered, Chiron may not (A) amend the quantities
of Blood Screening Assays from the quantities specified for the first (1st),
second (2nd) and third (3rd) calendar months in the immediately preceding
Forecast; (B) amend the quantities of Blood Screening Assays specified in the
Forecast for the fourth (4th), fifth (5th) and sixth (6th) calendar months in
the immediately preceding Forecast to an amount that is less than [***] nor more
than [***] of the amount forecasted when the month being amended was the sixth
(6th) calendar month; (C) amend the quantities of Blood Screening Assays
specified in the Forecast for the seventh (7th) calendar month in the
immediately preceding Forecast as it transitions to the sixth (6th) calendar
month in the delivered Forecast to an amount that is less than [***] nor more
than [***] of the quantity of Blood Screening Assays specified in the previous
Forecast when the month in question was the seventh (7th) calendar month; or
(D) amend the quantities of Blood Screening Assays specified in the Forecast for
the eighth (8th) calendar month in the immediately preceding Forecast as it
transitions to the seventh (7th) calendar month in the delivered Forecast to an
amount that is less than [***] nor more than [***] of the quantity of Blood
Screening Assays specified in the previous Forecast when the month in question
was the eighth (8th) calendar month. For example, on January 1, Chiron will
deliver a Forecast in which February is the first (1st) calendar month and
September is the eighth (8th) calendar month of the Forecast. If Chiron
estimates in such Forecast that in August, the seventh (7th) calendar month, it
will require [***] tests, Chiron may not decrease its Forecast below [***] tests
nor increase it above [***] tests as that month transitions to the sixth (6th)
calendar month in the next Forecast. Similarly, if Chiron estimates in a
Forecast that in September, the eighth (8th) calendar month, it will require
[***] tests, then in the subsequent Forecast Chiron may not decrease its
Forecast below [***] tests nor increase it above [***] tests when that month
transitions to the seventh (7th) calendar month. For purpose of the convenience
of reference hereafter, the Forecast delivered in which the applicable calendar
month is the eighth (8th) month is referred to as the "original Forecast"; and
the quantity as forecast in any subsequent Forecast, amended as permitted under
this Section (i.e. the Forecast delivered in which the applicable month
transitions to the next lower month, such as from the eighth (8th) month to the
seventh (7th)), is referred to as the "amended Forecast."

        (v)    Notwithstanding the provisions of subparagraph (iv) above, the
parties acknowledge that Gen-Probe incurs substantial expense ramping up
production and otherwise preparing to meet quantities forecasted by Chiron, even
in periods commencing the seventh (7th) calendar month and beyond in the
then-current Forecast. Therefore, the parties agree that Chiron may not reduce
the Forecast down under subparagraph (iv)(B) and (C), above, in the aggregate to
an amount that is less than [***] of the highest quantity of Blood Screening
Assays specified in any Forecast. (For example, on January 1, Chiron will
deliver a Forecast in which

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February 1 is the first (1st) month and September is the eighth (8th) month of
the Forecast. If Chiron estimates in such Forecast that in September it will
require [***] tests, then Chiron may not amend the Forecast, at any time or in
the aggregate, to an amount that is less than [***] tests deliverable in
September. In addition, if, in the subsequent Forecast when the month in
question transitions from the eighth (8th) to the seventh (7th) month, Chiron
increases the Forecast of the month in question from [***] tests to [***] tests,
then Chiron may not amend the Forecast to an amount that is less than [***]
tests deliverable in September (i.e. [***]). Similarly, if in the next Forecast,
when the month in question transitions from the seventh (7th) to the sixth (6th)
month, Chiron further increases the Forecast to [***] tests, then Chiron may not
amend the Forecast to an amount that is less than [***] tests deliverable in
September (i.e. [***]).)

        (b)    Commencing in the first full month following the Amendment
Effective Date, the parties shall meet monthly, on or before the twenty-second
(22nd) day of each calendar month, to review the previous month's performance
and the current Forecast and production plan for the purpose of making
production planning and inventory management decisions necessary to meet
Customer supply needs in a cost-efficient manner. Such production planning
meetings shall be attended by qualified members of each party, and shall be
sponsored by Chiron's Director of Global Supply Chain Management and Gen-Probe's
Vice-President of Manufacturing—Blood Products. The parties shall implement a
standing agenda in the form set forth in Schedule A.2, attached hereto, and may
consider such additional information as is agreed upon by both parties.

        (c)    In the event that any disagreement arises between the parties
pursuant to the obligations imposed in this Section 6.3.1, the parties shall
submit such dispute first to a discussion between responsible managers, and if
they cannot agree, then to the Supervisory Board for resolution as soon as is
reasonably achievable. In the event that the Supervisory Board is (i) unable to
resolve the issue at its next meeting, or (ii) is unable or unwilling to meet
within the thirty (30) day period after submittal of the issue to the
Supervisory Board, then the issue shall be referred by the parties for
resolution in accordance with the terms of Article 13 herein.

        6.3.2    Purchase Obligation.

        (a)  Chiron shall be required to purchase, in the respective month, the
quantity of Blood Screening Assays, by part number, specified in each Forecast
for the first (1st), second (2nd) and third (3rd) calendar months covered by
each Forecast. If any Forecast fails to conform to with the provisions of
Section 6.3.1, considered in the aggregate, then for purposes of determining
Chiron's purchase obligation under this Section 6.3.2(a) such non-conforming
Forecast shall be revised to comply with such provisions of Section 6.3.1.

        (b)  Notwithstanding anything in this Agreement to the contrary, the
expiration or sooner termination of this Agreement, other than a termination by
Chiron for default of Gen-Probe in accordance with the provisions of
Section 11.2.1 and subject to the provisions of Section 15.2 governing force
majeure events, shall not operate to extinguish Chiron's obligation to purchase
the quantity of Blood Screening Assays specified in accordance with
Section 6.3.1 through the eighth (8th) calendar month covered by the Forecast in
effect as of the effective date of expiration or sooner termination.

        (c)  In the event that any disagreement arises between the parties
pursuant to the obligations imposed in this Section 6.3.2, the parties shall
submit such dispute first to a discussion between responsible managers, and if
they cannot agree, then to the Supervisory Board for resolution as soon as is
reasonably achievable. In the event that the

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Supervisory Board is (i) unable to resolve the issue at its next meeting, or
(ii) is unable or unwilling to meet within the thirty (30) day period after
submittal of the issue to the Supervisory Board, then the issue shall be
referred by the parties for resolution in accordance with the terms of
Article 13 herein.

        6.3.3    Purchase Orders.

        (a)  Chiron shall submit to Gen-Probe a binding Purchase Order on or
before the fifth (5th) day of each calendar month during the term hereof
covering the Blood Screening Assays forecasted by Chiron for the third (3rd)
calendar month covered by the then-current Forecast (for example, on January 5,
Chiron will submit a Purchase Order for Blood Screening Assays to be delivered
in April). Each Purchase Order shall be in writing and reasonably similar to the
sample Purchase Order attached hereto as Schedule A.3. Each Purchase Order shall
specify the quantity of Blood Screening Assays ordered (by packaging
configuration, including kit size and/or catalogue part number), the place of
delivery, the requested delivery date, and such other information as Gen-Probe
reasonably requests. Chiron may not request a delivery date for any Blood
Screening Assays that is less than eighty-five (85) days or more than
ninety-five (95) days after the date of the applicable Purchase Order (for
example, a Purchase Order submitted to Gen-Probe on January 5 may only specify a
delivery date between the first and the tenth of April).

        (b)  Purchase Orders submitted to Gen-Probe by Chiron shall be binding
on Gen-Probe as to that quantity of Blood Screening Assays set forth in the
then-current Forecast for such calendar month. If the quantity of any Blood
Screening Assays ordered by Chiron for any calendar month exceeds the quantity
of such Blood Screening Assays set forth in the then-current Forecast for such
month, then Gen-Probe shall use Commercially Reasonable Efforts to deliver the
amount of Blood Screening Assays in excess of the forecasted amount. Gen-Probe
shall provide Chiron with written notice of the anticipated delivery date for
such additional Blood Screening Assays.

        (c)  In the event that any Purchase Order received from Chiron herein
fails to order Blood Screening Assays of the types and in the amounts specified
in the then-current Forecast for the applicable calendar month, Gen-Probe shall
have the right to reject such Purchase Order(s). Gen-Probe shall notify Chiron
in writing within ten (10) days of receipt of such Purchase Order(s). If not
rejected by Gen-Probe within ten (10) days of receipt, such Purchase Order(s)
shall be deemed accepted by Gen-Probe. In the event that Gen-Probe rejects a
purchase order Chiron shall have 5 days to correct the purchase order and
resubmit it to Gen-Probe.

        (d)  In the event that any disagreement arises between the parties
pursuant to the obligations imposed in this Section 6.3.3, the parties shall
submit such dispute first to a discussion between responsible managers, and if
they cannot agree, then to the Supervisory Board for resolution as soon as is
reasonably achievable. In the event that the Supervisory Board is (i) unable to
resolve the issue at its next meeting, or (ii) is unable or unwilling to meet
within the thirty (30) day period after submittal of the issue to the
Supervisory Board, then the issue shall be referred by the parties for
resolution in accordance with the terms of Article 13 herein.

        (e)  In the event of a conflict between the terms and conditions of any
Purchase Order and this Agreement, the terms and conditions of this Agreement
shall prevail.

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        6.3.4    Inventory.

        (a)  The parties agree that the amount of inventory sufficient to ensure
uninterrupted testing by Customers in the event of a disruption of supply of
Blood Screening Assays from Gen-Probe is a minimum of (5) months' forward demand
for such Blood Screening Assays, as determined by the most current Forecast.
Accordingly, Chiron shall purchase and maintain a minimum of a five (5) months
inventory of Blood Screening Assays based on the latest Chiron Forecast. The
five (5) months inventory will be maintained at Chiron's warehousing facilities
(which facilities are set forth in Schedule A.4 attached hereto). As Chiron
develops greater visibility of customer inventory, Chiron has the right to
reduce its inventory by including the inventory held at the customer sites.
However, Chiron must ensure that the inventory level held by Chiron (taking into
account up to five months' inventory that Chiron can show is held by each
customer) is sufficient to always supply each customer with a minimum of
5 months' supply. Prior to reducing their inventory, Chiron must submit their
inventory plan to the Supervisory Board for review and approval.

        (b)  Notwithstanding the foregoing, Gen-Probe shall maintain sufficient
inventory of raw materials and work in progress as necessary to meet the
production requirements for Chiron's commitments for the first through eighth
months of Chiron's most current Forecast.

        (c)  Each party shall give an independent certified public accounting
firm selected by the other party access to the applicable records (and the
applicable records of any Affiliate or Major Distributor) for the purpose of
permitting the audit, at the auditing party's expense and in accordance with
Section 7.3 of this Agreement, of compliance with this Section 6.3.4.

        6.3.5    Supply Obligation.

        (a)  Gen-Probe shall be required to supply in any given month the
quantity of Blood Screening Assays ordered by Chiron pursuant to a Purchase
Order as to that quantity of Blood Screening Assays set forth in the
then-current Forecast for such month, as the forecasted demand may be amended as
permitted in Section 6.3.1(a)(iv) above. If Gen-Probe becomes aware of any fact
indicating that Gen-Probe may be unable to meet Chiron's forecasted demand as
specified in the original Forecast as to any Blood Screening Assay or indicating
that Gen-Probe may be unable to meet Chiron's forecasted demand as specified in
an amended Forecast permitted under Section 6.3.1(a)(iv), Gen-Probe shall
promptly provide written notice of such fact to Chiron's Director of Global
Supply Chain Management and Gen-Probe's Vice-President of Manufacturing—Blood
Products. Chiron's Director of Global Supply Chain Management and Gen-Probe's
Vice-President of Manufacturing—Blood Products shall meet and attempt to agree
upon a resolution, including exploring ways to meet such increased demand. If
the parties cannot agree on such a resolution, then the issue will be referred
to the Supervisory Board for resolution no later than the latter of (i) thirty
(30) days after such referral, or (ii) the next regularly scheduled Supervisory
Board meeting. If the Supervisory Board fails to resolve the issue, the parties
may invoke the provisions of Article 13 herein. The failure of Gen-Probe to
supply that quantity of Blood Screening Assays in a Chiron Purchase Order in
excess of Chiron's forecasted demand as specified in the then-current Forecast
or amended Forecast, as permitted under Section 6.3.1(a)(iv) for such month,
shall not trigger the Chiron manufacturing rights set forth in Section 3.2.4(b)
of the Agreement.

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        (b)  Gen-Probe shall ensure that the expiration date for Blood Screening
Assays supplied to Chiron shall be no earlier than (i) eleven (11) months after
the date of delivery into warehouse inventory if designated for export; and
(ii) eight (8) months after the date of delivery into warehouse inventory if
designated for delivery in the United States. This provision only applies to
Lots of Blood Screening Assays manufactured after the Amendment Effective Date
(i.e., Lot 13 and beyond).

        (c)  The minimum expiration dating requirement set forth in
Section 6.3.5(b) exclude [***] and [***]. The parties will set dating
requirements for these products on or prior to June 30, 2002.

        6.3.6    Warehouse/Distribution Support for Order Processing. During the
term that Gen-Probe provides warehousing support under Section 6.4.4 of this
Agreement, Gen-Probe will provide reasonable staff support to Chiron, such staff
to be responsible for order packing and processing in connection with the sales
of Blood Screening Assays by Chiron. As of the Amendment Effective Date, such
support is estimated to be [***]. Changes to the number of Gen-Probe full-time
equivalent employees necessary to support order packing and processing shall
have no effect on this Agreement, but Gen-Probe will give Chiron reasonable
notice of such changes. Such employee(s) shall be responsible for (i) completing
order processing (including order packing and confirmations of shipment to
Chiron), (ii) maintaining files for special customer requirements, if any, and a
history of shipments for Chiron, (iii) maintaining familiarity with part numbers
and master lot requirements for Blood Screening Assays, and (iv) communicating
regularly with Chiron on Purchase Orders and shipments, recording/reporting
status of shipments, problem fact finding, and resolution of order and/or
shipment problems."

        3.    Delivery. Section 6.4.1 of the Agreement is hereby deleted and
replaced in its entirety by the following:

        "6.4.1    Delivery.

        (a)  For so long as Gen-Probe provides the warehousing support under
Section 6.4.4, all Blood Screening Assays purchased by Chiron under this
Agreement shall be transferred to the warehouse location more particularly
described in Section 6.4.4 without shipping charges to Chiron. Chiron shall be
responsible for the cost of shipment out of such warehouse facility to any other
location, including to Chiron Customers.

        (b)  At such time as Gen-Probe no longer provides the warehousing
support under Section 6.4.4, all Blood Screening Assays purchased by Chiron
under this Agreement shall be shipped f.o.b. place of manufacture to such
location as designated by Chiron in the applicable Purchase Order. Chiron shall
have the right to select the carrier.

        (c)  Chiron shall be responsible for all freight, insurance charges,
taxes, import and export duties, inspection fees and other charges applicable to
the sale and transport of Blood Screening Assays purchased by Chiron (i) for
transfer out of the warehouse to Customers, during the period that Gen-Probe
provides the warehousing support under Section 6.4.4 and (ii) to such location
designated by Chiron in the applicable Purchase Order, at such time as Gen-Probe
no longer provides the warehousing support under Section 6.4.4. Gen-Probe shall,
to the extent possible, charge such expenses to Chiron's carrier accounts or
pre-pay such charges. When Gen-Probe pre-pays such charges, it shall invoice
such charges to Chiron in reasonable detail, specifying the Blood Screening
Assays to which such charges apply. Chiron shall pay all such invoices within
thirty (30) days of date of invoice.

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        (d)  When Blood Screening Assays are shipped from the Gen-Probe
warehouse, the dry ice fee of [***] for each shipping box containing frozen
material is a freight charge to be prepaid by Gen-Probe, and for which Gen-Probe
shall invoice Chiron. The dry ice fee, as well as the other charges enumerated
in Sections 6.4.1(a) and (c) above shall be deducted from the gross sales price
of Blood Screening Assays as set forth in Section 1.46 herein."

        4.    Warehousing. The following new Section 6.4.4 is hereby added to
the end of Section 6.4 of the Agreement:

        "6.4.4    Warehousing.

        (a)  Gen-Probe shall provide warehouse capability for Blood Screening
Assays after sale to Chiron, in accordance with the provisions of this
Section 6.4.4. Chiron may notify Gen-Probe in writing at any time after June 30,
2002 or earlier upon the breach by Gen-Probe of any of its obligations under
this Section 6.4.4, of its intention to assume the warehousing function
internally. Such notice shall indicate a date not less than 30 days after the
date of such notice on which Chiron will assume the warehousing function.
Gen-Probe may notify Chiron in writing on or before November 1 of any year
during the term hereof of its decision to terminate its provision of the
warehouse capabilities described in this Section 6.4.4 and inventory management
described in Section 6.4.5, effective January 1 of the immediately succeeding
year."

        (b)  Gen-Probe shall provide adequate warehouse storage at its Willow
Court facility for all Blood Screening Assays purchased by Chiron prior to
delivery of such Blood Screening Assays to Chiron or Chiron's Customer. Such
storage services shall include, as applicable based on the type of Blood
Screening Assay, frozen, refrigerated, and ambient physical storage space.
Gen-Probe shall maintain appropriate safety and security systems for such
storage space, including monitoring of frozen and cold facilities and providing
appropriate backup systems, in accordance with applicable state and federal
regulations.

        (c)  Gen-Probe shall maintain frozen inventoried Blood Screening Assays
in core-packs, unless otherwise agreed by the parties in writing.

        (d)  During the period in which Gen-Probe is providing warehousing
storage services to Chiron under this Section 6.4.4, Gen-Probe shall segregate,
as appropriate, any Blood Screening Assays being warehoused for Chiron pursuant
to this Section 6.4.4 and identify such Blood Screening Assays as Chiron's
property. Except as otherwise permitted in this Agreement, Gen-Probe shall not,
and shall not permit any third party to, sell, assign, pledge, encumber, dispose
of, or suffer a lien or encumbrance upon or against any interest in the Blood
Screening Assays held by Gen-Probe pursuant to this Section 6.4.4.

        (e)  Gen-Probe shall provide Chiron with information regarding all
transfers to Chiron, and Chiron shall track and maintain inventory in Chiron's
accounting system for all Blood Screening Assays held by Gen-Probe under this
Section 6.4.4. The parties shall cooperate in good faith in the performance of a
periodic inventory reconciliation between Chiron's records and a physical count
to be conducted on all Blood Screening Assays held by Gen-Probe pursuant to this
Section 6.4.4. Such reconciliation shall be conducted once every other month,
unless otherwise agreed to by the parties in writing. In the event that such
reconciliation identifies discrepancies, the parties shall investigate in good
faith the causes of such discrepancies. Each party shall rectify, at its
expense, any discrepancies identified which result from such party's failure to
act in accordance with the terms of this Agreement or reasonable business
practices. If a discrepancy cannot be attributed to either party, then Gen-Probe
shall rectify such discrepancy at its expense.

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        (f)    For so long as Gen-Probe provides warehousing support under this
Section 6.4.4 and for as long thereafter as necessary to cover claims resulting
from such warehousing support, Chiron shall maintain: (1) product liability and
general commercial liability insurance having a limit of not less than[***]; and
(2) property damage insurance at replacement value for the Blood Screening
Assays located at Gen-Probe's warehousing facility, pursuant to one or more
insurance policies with reputable insurance carriers. Chiron hereby waives
subrogation for the benefit of Gen-Probe with respect to the physical loss of
such Blood Screening Assays, except for losses due to the negligence of
Gen-Probe or a breach of Gen-Probe's obligations under this Section 6.4.4.
Chiron shall not cause or permit such insurance to be cancelled or modified to
materially reduce its scope or limits of coverage for so long as Gen-Probe is
providing warehousing support described in Section 6.4.4 or thereafter as
provided above.

        (g)  For so long as Gen-Probe provides warehousing support under this
Section 6.4.4 and for so long thereafter as necessary to cover claims resulting
from such warehousing support, Gen-Probe shall maintain commercial general
liability insurance in the amount of [***], including bailee's legal liability,
and Chiron shall be designated as an "additional insured" as respects its rights
under this Section 6.4.4. Gen-Probe shall maintain such other types of
insurance, with appropriate limits of liability, that are usual and customary
for the nature of Gen-Probe's warehousing operations pursuant to this
Section 6.4.4. Gen-Probe shall not cause or permit such insurance to be
cancelled or modified to materially reduce its scope or limits of coverage for
so long as Gen-Probe is providing warehousing support described in Section 6.4.4
or thereafter as provided above.

        (h)  Chiron shall be permitted reasonable access to Blood Screening
Assays held by Gen-Probe pursuant to this Section 6.4.4 during Gen-Probe's
normal business hours and upon reasonable notice to Gen-Probe. Chiron shall
retain the right to remove from Gen-Probe's warehouse facility all or any
portion of the Blood Screening Assays held by Gen-Probe pursuant to this
Section 6.4.4, upon reasonable advance notice to Gen-Probe.

        (i)    Gen-Probe shall have the right to require Chiron to dispose of,
or otherwise remove from Gen-Probe's warehousing facility, any and all Blood
Screening Assays stored by Gen-Probe pursuant to this Section 6.4.4 of which the
expiration date has passed.

        (j)    Except for any losses resulting from the negligence of Gen-Probe
or a breach of Gen-Probe's obligations under this Section 6.4.4, Chiron shall
bear all risk of loss or damage with respect to the Blood Screening Assays once
purchased by Chiron, whether located at Gen-Probe's warehousing facility or
elsewhere.

        (k)  Gen-Probe agreed in Supplemental Agreement to provide the warehouse
capabilities described in this Section 6.4.4 and inventory management described
in Section 6.4.5 for a period commencing on January 1, 2001 through December 31,
2001, and further agreed in the Settlement Agreement to extend the provision of
those services through December 31, 2002, subject to the right of Gen-Probe to
increase the charge for those services as limited by the CPI described in
Section 6.4.5(e).

        5.    Insurance Certificates.    

        5.1  Unless previously provided to Gen-Probe by Chiron, concurrent with
the execution of this Amendment No. 3, Chiron shall deliver to Gen-Probe
certificates evidencing the insurance referred to in Section 6.4.4(g) of the
Agreement, as amended by this Amendment No. 3.

        5.2  Unless previously provided to Chiron by Gen-Probe, concurrent with
the execution of this Amendment No. 3, Gen-Probe shall deliver to Chiron
certificates evidencing the insurance referred to in Section 6.4.4(h) of the
Agreement, as amended by this Amendment No. 3.

9

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        6.    Inventory Management. The following new Section 6.4.5 is hereby
added to the end of Section 6.4, following newly added Section 6.4.4:

        "6.4.5    Inventory Management: For so long as Gen-Probe is providing
the warehousing support services described under Section 6.4.4, the following
additional provisions shall apply:

        (a)    Gen-Probe will provide necessary staff support to Chiron, such
staff to be responsible, as described below, for inventory management and
shipping of Blood Screening Assays from Gen-Probe's San Diego facilities as
required under this Agreement. As of the Amendment Effective Date, such
necessary staff is estimated to be [***] employees. Changes in the number of
full-time equivalent employees necessary to support inventory management shall
have no effect on this Agreement, but Gen-Probe will give Chiron reasonable
notice of such changes.

        (b)    Gen-Probe shall, through the services of the support staff
designated under Section 6.4.5(a) above, provide the following services to
Chiron:

        (i)    Inventory management of all inventory, including reagents, Blood
Screening Instruments and parts, packing and shipping materials, etc.;

        (ii)    Packing of kitted components, including verification of all
kitted components to work order, transfer of kitted components into shipping
containers, application of dry ice, gel packs, etc. as required and final
assembly and quality control of shipping containers;

        (iii)    Arrangement of and handling transfer to freight forwarders of
all shipments of reagents, ancillaries (TTU, TTC, sealing cards, etc.) and Blood
Screening Instruments, using Chiron's carrier accounts for freight charges;

        (iv)    Entry of all appropriate system transactions to process
shipments, including material issue transactions, printing and application of
shipping labels and packing slips;

        (v)    Completion of shipping paperwork, including freight bills and/or
SLI's, dangerous goods forms and maintenance of records; and

        (vi)    Interaction with carriers, including pre-arranging pick-ups,
faxing of paperwork to carriers and Chiron to reserve appropriate space on
flights, loading carrier upon arrival, forwarding all paperwork to appropriate
finance and record-keeping personnel, performing any post-shipment follow-up to
ensure timely delivery, informing interested parties of results, and
investigating any post-shipment problems such as flight delays, orders canceled
prior to pick-up, product returns, etc.

        (c)  Gen-Probe will be responsible for arranging direct shipments to
Customers located in the United States. With respect to shipments outside the
United States, Gen-Probe shall only be responsible for arranging shipments to
Chiron's primary foreign distribution points (where such Chiron distribution
points exist), not to exceed one such distribution point per country.

        (d)  When Chiron desires that Blood Screening Assays be shipped to a
Customer out of Chiron's inventory held by Gen-Probe under Section 6.4.4, Chiron
will provide Gen-Probe with a shipping request. Each shipping request shall be
in writing and in a form mutually agreeable to Chiron and Gen-Probe. Gen-Probe
will use Commercially Reasonable Efforts to ship Blood Screening Assays so that
the Blood Screening Assays will arrive at the designated Customer location by
the delivery date set forth in such request, at Chiron's expense. Gen-Probe will
give special attention to emergency orders,

10

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but shall not be in breach of such obligation if Gen-Probe has used Commercially
Reasonable Efforts to expedite shipment for such emergency orders.

        (e)  Chiron shall pay to Gen-Probe a monthly fee of [***] for the
warehousing services rendered by Gen-Probe pursuant to Section 6.4.4 and the
inventory management services described in this Section 6.4.5. Gen-Probe shall
have the right to invoice Chiron, and payment to Chiron will be due on the fifth
(5th) day of each month. Gen-Probe shall have the right to increase such monthly
fee once in each twelve (12) month period, provided, that (i) the increase for
the period January 1 through December 31, 2002 shall not exceed an amount equal
to [***] multiplied by a fraction (1) the numerator of which is the index number
in the Consumer Price Index for the Standard Metropolitan Statistical Area (or
equivalent) that then includes San Diego, California, as published by the U.S.
Department of Labor or other authoritative federal government agency, for
October 1, 2001 and (2) the denominator of which is said index number for
October 1, 2000 and (ii) increases in such monthly fees for periods subsequent
to December 31, 2002 shall be limited in this same fashion. Payments that are
past-due under this Section shall bear a late payment charge at the lesser of
the London Interbank Offered Rate (LIBOR) or the highest rate permitted by
applicable law."

        (f)    Promptly following any termination of the provision of
warehousing support services described under Section 6.4.4, the parties will
meet to consider the reduced inventory management, packing and shipping needs of
Chiron, and amend this Section 6.4.5 accordingly."

        7.    Safety Stocks. Section 6.12 (Safety Stocks) is hereby deleted and
replaced, in its entirety, as follows:

        "6.12    Safety Stocks.    

        (a)  The Supervisory Board will from time-to-time review and establish
the appropriate level of Safety Stocks for the Blood Screening Assays. The
parties agree that the appropriate level of Safety Stock for the Initial Blood
Screening Assay as of the Amendment Effective Date is reflected in the five
month inventory requirement described in Section 6.3.4 above.

        (b)  With respect to any Initial Blood Screening Assay or Future Blood
Screening Assay, the objective of the parties is to share equally the aggregate
cost of maintaining safety stocks of raw components, work in progress, and
finished goods as required by CBER."

        8.    Scope of Amendment No. 3. The parties hereto agree that the
Forecasts and Orders provisions set forth in Section 2 of this Amendment No. 3
address the rights and obligations of each party with respect to Lot 13 and
subsequent Lots. Except as expressly stated herein, nothing in Section 2 of this
Amendment No. 3 shall apply in any respect to the rights or obligations of the
parties with respect to Lots 1-12. Accordingly, and for ease of implementation,
the parties agree that the Forecast and Orders provisions set forth in Section 2
will apply commencing with and applying to the Forecast due April 1, 2002 from
Chiron (covering the 12 months ending April 30, 2003). Notwithstanding the
above, the Order Processing provisions of new Section 6.3.6 shall govern the
rights and obligations of each party from and after the Amendment Effective
Date. Except as set forth in this Section 8, from and after the Amendment
Effective Date, this Amendment No. 3 shall apply in all respects to the
Agreement.

        9.    Limited Terms Applicable to [***]. The parties agree to equally
share the "variable manufacturing cost" of those portions of [***] held in
inventory by Gen-Probe and Chiron that are unsold, not retained for R&D or other
internal purpose by either party and scrapped due to product expiration, net of
the aggregate purchase price previously paid by Chiron to Gen-Probe for expired

11

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units held in Chiron's inventory. For the purpose of this Amendment No. 3, [***]
will be used as the "variable manufacturing cost" to value scrap material. To
the extent necessary to avoid product outdating and if requested by Chiron,
Gen-Probe agrees to re-label, at Gen-Probe's expense and in accordance with all
international and domestic labeling requirements, such Blood Screening Assays in
[***] that may be relabeled with twenty-four (24) month expiration dates.

        10.    Effect of Amendment No. 3 on Supplemental Agreement. As of the
Amendment Effective Date, the Supplemental Agreement shall terminate in all
respects. Each party's obligations under such Supplemental Agreement shall
terminate as of such date; provided, however, that such termination shall not
act to bar claims under the terms of the Supplemental Agreement that arose prior
to such Amendment Effective Date.

        11.    No Other Amendment. Except as is expressly set forth in this
Amendment No. 3, all other terms and conditions of the Agreement and the
Settlement Agreement are hereby ratified and shall continue in full force and
effect.

        12.    Counterparts. This Amendment No. 3 may be executed in
counterparts, each of which shall be deemed an original, and all of which
together shall constitute one and same instrument.

        IN WITNESS WHEREOF, the parties have caused this Amendment No. 3 to be
executed as of April 1, 2002 and the persons signing below warrant that they are
duly authorized to sign for and on behalf of the respective parties.

Gen-Probe:   Chiron:
GEN-PROBE INCORPORATED,
 
CHIRON CORPORATION a Delaware corporation   a Delaware corporation
By /s/  HENRY L. NORDHOFF      
 
By /s/ WILLIAM G. GREEN

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Henry L. Nordhoff  

--------------------------------------------------------------------------------

William G. Green President and Chief Executive Officer   Senior Vice President
and President, Blood Testing [SEAL]
[which reads:
APPROVED
Bowen
Legal Dept]    

12

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Schedule A.1

Labeling Requirements

Part Number

--------------------------------------------------------------------------------

  Description

--------------------------------------------------------------------------------

  Label Options

--------------------------------------------------------------------------------

[***]   [***]   [***]

13

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Schedule A.2

Standing Agenda for Production Planning Meetings

Purpose:

        Review Forecast and production plan and make the appropriate production
planning and inventory management decisions to meet Customer supply needs in a
cost efficient manner.

Agenda:

        —    Review previous month performance

        —    Shipments

        —    Inventory

        —    Production

        —    Delivery

        —    Review current Forecast and production plan

        —    [***]

        —    Timing/feasibility for next production?

        —    "What If analysis"—Risk and risk management discussion

        —    Outstanding issues [***]

        —    Review Plan and Key Decisions.

14

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Schedule A.3

Sample Purchase Order

15

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    CHIRON Purchase order   Supplier:
P.O. # 45059813
Order Date: 21-May-2002
Buyer: Mary Semeniuk
Phone #: 510-923-6010
Fax #: 510-923-3340
 
GEN-PROBE INCORPORATED
10210 GENETIC CENTER DRIVE
SAN DIEGO CA 92121
Vendor Contact: SHERYL STILES
Phone #: 858-410-8984
Fax #: 800-288-3141

        A copy of this purchase order was faxed to Sheryl Stiles at Gen-Probe.

Equal Opportunity Contract Clause (EOC)
Chiron Corporation is committed to the provisions outlined in the Equal
Opportunity Clauses of Executive Order 11246, (60-1.4), Section 503 of the
Rehabilitation Act of 1973, (60-741.5), and, Section 402 of the Vietnam Veterans
Readjustment Act of 1974, (60-250.4), As well as any other regulations
pertaining to these orders.

        Please fax a copy of the packing list to Erica Artis at Chiron Corp at
510-923-2786.

Item #

--------------------------------------------------------------------------------

  QTY/UOM

--------------------------------------------------------------------------------

  Chiron Mat #
Vendor Mat #
Material Description

--------------------------------------------------------------------------------

  Price

--------------------------------------------------------------------------------

  Extended Price

--------------------------------------------------------------------------------

1   170 EA   [***]
301030-PROCLEIX (TM) 5000 IVD TEST KIT
[***]
[***]   [***] per EA   [***] 2   35 EA   [***]
301031
301031-PROCLEIX (TM), 1000 IVD TEST KIT
[***]
[***]   [***] per EA   [***] 3   885 EA   [***]
301027-PROCLEIX (TM), ASSAY FLUIDS, IVD
[***]
[***]   [***] per EA   [***] 4   443 EA   [***]
301038-PROCLEIX (TM), AUTO DETECT, IVD
[***]
[***]   [***] per EA   [***]

16

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    CHIRON Purchase order   Supplier:
P.O. # 45059813
Order Date: 21-May-2002
Buyer: Mary Semeniuk
Phone #: 510-923-6010
Fax #: 510-923-3340
 
GEN-PROBE INCORPORATED
10210 GENETIC CENTER DRIVE
SAN DIEGO CA 92121
Vendor Contact: SHERYL STILES
Phone #: 858-410-8984
Fax #: 800-288-3141

Item #

--------------------------------------------------------------------------------

  QTY/UOM

--------------------------------------------------------------------------------

  Chiron Mat #
Vendor Mat #
Material Description

--------------------------------------------------------------------------------

  Price

--------------------------------------------------------------------------------

  Extended Price

--------------------------------------------------------------------------------

5   575 EA   [***]
301026-PROCLEIX (TM), DISCR PROBE, IVD
[***]   [***] per EA   [***] 6   60 EA   [***]
301036
301036-PROCLEIX (TM), HIV-1/HCV CALIB, IVD
[***]   [***] per EA   [***] 7   465 EA   [***]
301035
301035-PROCLEIX (TM), HIV-1/HCV CONTR,IVD
[***]   [***] per EA   [***] 8   50 EA   [***]
301034
301034-PROCLEIX (TM), PROF PANELS, IVD
[***]   [***] per EA   [***] 9   885 CAS   [***]
GP
TU0022-TEN TUBE UNIT (TTU), ESAS
[***]   [***] per CAS   [***] 10   885 CAS   [***]
GP
104578-TEN TUBE CASSETTE (TTC)
[***]   [***] per CAS   [***] 11   7,630 CAS   [***]
GP
102085-SEALING CARDS (35/PKG)
[***]   [***] per CAS   [***] 12   38 EA   [***]
[***]
[***]   [***] per EA   [***]

17

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    CHIRON Purchase order   Supplier:
P.O. # 45059813
Order Date: 21-May-2002
Buyer: Mary Semeniuk
Phone #: 510-923-6010
Fax #: 510-923-3340
 
GEN-PROBE INCORPORATED
10210 GENETIC CENTER DRIVE
SAN DIEGO CA 92121
Vendor Contact: SHERYL STILES
Phone #: 858-410-8984
Fax #: 800-288-3141

Item #

--------------------------------------------------------------------------------

  QTY/UOM

--------------------------------------------------------------------------------

  Chiron Mat #
Vendor Mat #
Material Description

--------------------------------------------------------------------------------

  Price

--------------------------------------------------------------------------------

  Extended Price

--------------------------------------------------------------------------------

        [***]                 Total Net Item Value Excluding Tax       [***] USD

 
   

 
 
  Free on board SHIPPING POINT
Shipment Terms: Within 30 days Due net    
Remit To:
 
Deliver To: Chiron Corporation
Accounts Payable Department
4560 Horton Street
Emeryville, CA 94608
Attn: P.O.# 45059813   Chiron Warehouse
C/O Gen-Prove Incorporated
10808 Willow Court
San Diego CA 92127

Attn: P.O.# 45059813

 
   
   
   
Supplier Confirmation By:       For Chiron Corp. By:        

--------------------------------------------------------------------------------

     

--------------------------------------------------------------------------------

(If Requested)   Authorized Agent, Title, Date       Authorized Agent, Title
Date

18

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Schedule A.4

List of Warehousing Facilities

[***]

[***]

[***]

***Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

19

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QuickLinks

Exhibit 10.318

AMENDMENT NO. 3 TO AGREEMENT
Recitals
Agreement
Schedule A.1 Labeling Requirements
Schedule A.2 Standing Agenda for Production Planning Meetings
Schedule A.3 Sample Purchase Order
Schedule A.4 List of Warehousing Facilities