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Exhibit 10.517

CHIRON CORPORATION
SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

(As Amended and Restated Effective March 1, 2003)

ARTICLE I
PURPOSE

        This Plan is designed to restore to selected employees of Chiron
Corporation and its affiliates certain benefits that cannot be provided under
the Chiron 401(k) Plan. It shall be effective for compensation earned after
December 31, 1997 and to permit additional deferrals of annual bonuses.

        This Plan is intended to be a plan that is unfunded and that is
maintained by Chiron Corporation primarily for the purpose of providing deferred
compensation for a select group of management or highly compensated employees
within the meaning of the Employee Retirement Income Security Act of 1974
("ERISA").

ARTICLE II
DEFINITIONS

        In this Plan, the following terms have the meanings indicated below:

        2.01    "Account"    means a bookkeeping entry used to record
supplemental deferrals and contributions made on a Participant's behalf under
Article III and Article VII of the Plan and any earnings credited to these
supplemental deferrals and contributions under Article IV or Article VII of the
Plan. To the extent it considers necessary or appropriate, the Committee or its
delegate shall maintain separate a subaccount for each type of supplemental
deferral or contribution under the Plan or shall otherwise provide a means for
determining that portion of an account attributable to each type.

        2.02    "Affiliate"    means an entity other than the Company whose
employees participate in the 401(k) Plan.

        2.03    "Beneficiary"    means the person or persons, natural or
otherwise, entitled to receive a Participant's vested Account if the Participant
dies before distribution of his or her entire vested Account. A Participant's
Beneficiary shall, at any time, be the person or persons then designated,
whether affirmatively or by default, as the Participant's beneficiary under the
401(k) Plan. If the Participant no longer has a beneficiary under the 401(k)
plan, the Participant may designate one or more primary Beneficiaries and one or
more secondary Beneficiaries for purposes of this Plan. Any such designation
will be made in writing pursuant to such procedures as the Committee may
establish and delivered to the Committee before the Participant's death. The
Participant may revoke or change this designation at any time before his or her
death by following such procedures as the Committee may establish. If there is
no effective Beneficiary designation on file when such a Participant dies, the
Participant's vested Account will be distributed to the Participant's spouse if
surviving at the Participant's death, or if there is no such spouse, the
Participant's estate.

        2.04    "Bonus"    means the component of an Eligible Employee's
Compensation paid in the form of an annual cash bonus.

        2.05    "Chiron 401(k) Plan"    means the Chiron Corporation 401(k)
Plan, as amended from time to time.

        2.06    "Code"    means the Internal Revenue Code of 1986, as amended.

        2.07    "Committee"    means the committee established pursuant to
Article XIV of the Chiron 401 (k) Plan, as constituted from time to time. The
Committee has full discretionary authority to administer

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and interpret the Plan, to determine eligibility for Plan benefits, to select
employees for Plan participation, and to correct errors. The Committee may
delegate its duties and responsibilities and, unless the Committee expressly
provides to the contrary, any such delegation will carry with it the Committee's
full discretionary authority to accomplish the delegation. Decisions of the
Committee and its delegate will be final and binding on all persons.

        2.08    "Company"    means Chiron Corporation.

        2.09    "Compensation"    means compensation as established pursuant to
Article II of the Chiron 401 (k) Plan, as constituted from time to time.

        2.10    "Eligible Employee"    means an employee of the Company or of an
Affiliate at the level of any executive salary grade position who has been
selected by the Committee for Plan participation. An individual will
automatically cease to be an Eligible Employee on the earliest of (i) the date
the individual ceases to be an employee of the Company or an Affiliate at the
level of an executive salary grade position, (ii) the date specified by the
Committee for such cessation or (iii) the date the Plan is terminated.

        2.11    "Matching Contribution"    means a matching contribution
pursuant to Section 5.02 of the Chiron 401(k) Plan.

        2.12    "Participant"    means a current or former Eligible Employee who
retains an Account.

        2.13    "Plan"    means this Chiron Corporation Supplemental Executive
Retirement Plan, as amended from time to time.

        2.14    "Plan Year"    means the plan year defined in the Chiron 401
(k) Plan.

        2.15    "Plan Year Account"    means, for each Plan Year, that portion
of an Eligible Employee's Account that is attributable to (i) Compensation that
would have been paid in such Plan Year had payment not been deferred under this
Plan and (ii) interest credited thereto pursuant to Article IV.

        2.16    "Retirement Contribution"    means a retirement contribution
pursuant to Section 5.03 of the Chiron 401(k) Plan.

        2.17    "Salary Deferral"    means a salary deferral pursuant to
Section 5.01 of the Chiron 401(k) Plan.

        2.18    "Special Deferred Compensation Arrangement"    means any written
deferred compensation arrangement entered into between and signed by an Eligible
Employee and the Company, or an Affiliate thereof, which is approved by the
Committee or its delegate pursuant to Section 7.01 hereof.

        2.19    "Termination of Employment"    means termination of employment
with the Company and all Affiliates, other than by reason of death.

ARTICLE III
DEFERRALS AND CONTRIBUTIONS

        3.01    Supplemental Salary Deferrals.    

        (a)    Elections.    In order to be eligible for supplemental salary
deferrals for each Plan Year, an Eligible Employee must make an election to make
Salary Deferrals for such Plan Year. Such election generally must be made before
the calendar year in which the Compensation is earned, in accordance with such
procedures as the Committee shall specify. However, if an individual first
becomes an Eligible Employee during a Plan Year, an Eligible Employee may elect,
within 30 days after he or she is first notified that he or she is eligible to
participate in the Plan, to defer Compensation for services performed during
that Plan Year and after the election. Elections will remain in effect for one
Plan Year or, if the Committee so permits, all subsequent Plan Years

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during which the individual remains an Eligible Employee. Such election may be
revoked, but any revocation cannot be made effective before the first day of the
first Plan year beginning after the date the revocation is filed.

        (b)    Late Election.    If an Eligible Employee does not make a timely
election for a Plan Year, no supplemental salary deferral will be made under the
Plan on behalf of that Eligible Employee with regard to that election for that
Plan Year.

        (c)    Amount.    The amount of an Eligible Employee's supplemental
salary deferral will be equal to the portion of the Salary Deferral otherwise
elected by such Eligible Employee which could not be contributed to the Chiron
401(k) Plan due to the limitations of Code Sections 401(a)(17), 402(g)(1)
and/or 415.

        (d)    Special Election for Bonuses.    For Plan Years beginning after
December 31, 2001, an Eligible Employee may make a separate salary deferral
election with respect to the Eligible Employee's Bonus that will be paid in such
Plan Year. The portion of the Bonus that may be deferred pursuant to this
election is any percentage that, when added to the maximum percentage of Salary
Deferral that he may elect, does not exceed one hundred percent (100%) of such
Bonus.

        (e)    Crediting.    Supplemental salary deferrals will be credited to
Eligible Employees' Accounts as of the date that the Salary Deferrals to which
the supplemental salary deferrals relate would otherwise have been credited to
the Chiron 401 (k) Plan.

        3.02    Supplemental Matching Contributions.    

        (a)    Amount.    The amount of an Eligible Employee's supplemental
matching contribution for a Plan Year will be equal to the amount by which that
Eligible Employee's Matching Contribution for that Plan Year was reduced due to
the reduction of such Eligible Employee's Salary Deferral or Matching
Contributions as a result of the Code Sections 401(a)(17), 402(g)(1) and/or 415;
provided that supplemental matching contributions attributable to Salary
Deferral reductions under the Chiron 401(k) Plan shall not be made unless
supplemental salary deferrals equal to such reductions are made hereunder.

        (b)    Crediting.    Supplemental Matching Contributions will be
credited to Eligible Employees' Accounts as of the date that the Matching
Contributions to which the Supplemental Matching Contributions relate would
otherwise have been credited to the Chiron 401 (k) Plan.

        3.03    Supplemental Retirement Contributions.    

        (a)    Amount.    The amount of an Eligible Employee's supplemental
retirement contribution for a Plan Year will be equal to the amount by which
that Eligible Employee's Retirement Contribution for that Plan Year was reduced
as a result of Code Sections 401(a)(17) and/or 415.

        (b)    Crediting.    Supplemental retirement contributions will be
credited to Eligible Employees' Accounts as of the date that the Retirement
Contributions to which such Supplemental Retirement Contributions relate would
otherwise have been credited to the Chiron 401(k) Plan.

ARTICLE IV
EARNINGS

        Interest will be credited to each Account at the end of each calendar
quarter, in accordance with procedures approved by the Committee. The interest
rate used will be based on the Moody's Corporate Bond Yield Average. The
Corporate Bond Yield Average is equal to the average of the Moody's Corporate
AAA, AA, A and BAA Bond Yield Averages, determined as of the first business day
of that quarter. The first quarter for which interest will be credited is the
calendar quarter beginning January 1, 1998.

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ARTICLE V
VESTING

        Participants will be 100% vested in that portion of their Accounts
attributable to supplemental salary deferrals and supplemental matching
contributions and will vest in that portion of their Accounts attributable to
supplemental retirement contributions in the same manner that they vest in
Retirement Contributions. That portion of a Participant's Account attributable
to amounts deferred under a Special Deferred Compensation Arrangement shall vest
in accordance with the terms of that arrangement.

ARTICLE VI
DISTRIBUTIONS

        6.01    Standard Distribution Options    

        (a)    General.    Subject to Sections 6.01(b) (relating to Retirement),
Section 6.02 (relating to distributions following death), Section 6.03 (relating
to accelerated distributions) and Article VII (relating to certain distributions
of Special Deferred Compensation Arrangements) each Plan Year Account of a
Participant, to the extent vested, will be distributed in a lump sum within
30 days following the earlier of

(i)the date 30 days after the Participant's Termination of Employment or, if the
Participant so elects, the January 15 of the calendar year immediately following
the Participant's Termination of Employment or

(ii)for each Plan Year Account attributable to a Plan Year beginning after
December 31, 2001, March 1 of any calendar year that begins at least two years
after the beginning of such Plan Year (the "Specified Payment Date"). Although a
Participant may elect a separate Specified Payment Date for each Plan Year
Account, the Plan Administrator may specify a limit on the total number of
different Specified Payment Dates that a Participant may elect with respect to
all Plan Year Accounts.

        (b)    Retirement.    An Eligible Employee may also elect that if, at
the time of Termination of Employment, he or she both (i) reached age fifty-five
(55) and (ii) been employed by the Company for a period of at least ten
(10) years, payment of his or her vested Account will be distributed, in lieu of
the time and form of distribution set forth in (a) above, beginning on a date
following Termination of Employment elected by the Eligible Employee, but not
later than Participant's 65th birthday (or if later, the first March 1 following
Termination of Employment), and may be made in a single lump sum or in annual
installments, not in excess of 10. The amount of each installment will be the
remaining balance of the Participant's vested Account divided by the number of
installments remaining (including the installment to be made).

        (c)    Elections.    Any election made by an Eligible Employee with
respect to a Plan Year Account under (a) or (b) above must be made at such time
and in such manner as the Committee may specify, but not later than the deadline
for electing to defer compensation otherwise payable in such Plan Year. If the
Committee so determines, an election may apply to all subsequent Plan years,
until revoked in writing before the first Plan Year for which it is intended to
be revoked. A Participant may change a distribution election with respect to a
Plan Year Account by submitting the change to the Committee at such time and in
such manner as the Committee shall specify. However, any election eliminating or
changing a Specified Payment Date must be made at least two years before the
previously Specified Payment Date and any new Specified Payment Date must be
March 1 of a calendar year that is not earlier than the second calendar year
beginning after the new election is made. Any change in the time or manner in
which a Plan Account is distributed following Termination of Employment will be
valid only if Termination of Employment occurs more than two years after the
date of such subsequent election.

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        (d)    Default.    Subject to Article VII (relating to certain
distributions of Special Deferred Compensation Arrangements), if upon a
Participant's Termination of Employment, the Committee does not have a proper
distribution election on file for that Participant, the vested portion of that
Participant's Account will be distributed to the Participant in one lump sum
within the period 30 to 60 days after the Participant's Termination of
Employment.

        6.02    Death.    Subject to Article VII (relating to certain
distributions of Special Deferred Compensation Arrangements), if a Participant
dies with a vested amount in his or her Account, whether or not the Participant
was receiving payouts from that Account at the time of his or her death, the
Participant's Beneficiary will receive the entire vested amount in the
Participant's Account within the 30 day period beginning 30 days after (and
ending 60 days after) the Committee learns of the Participant's death and has
verified the Beneficiary's right to payment.

        6.03    Accelerated Distributions.    Pursuant to the following
restrictions, a Participant may accelerate the time and form of distribution:

        (a)    Hardship Withdrawal.    If a Participant has a severe financial
hardship resulting from extraordinary and unforeseen circumstances beyond the
Participant's control and has no other resources that could be liquidated or
otherwise accessed to relieve this hardship without such liquidation or access
itself causing a severe financial hardship, the Participant may request a
hardship withdrawal. The total hardship withdrawal must be approved by the
Committee, and shall be limited to the amount necessary to meet the financial
need and to satisfy the Participant's tax liability with respect to such
withdrawal, and in no event may such amount exceed that portion of the
Participant's Account attributable to supplemental salary deferrals and
supplemental matching contributions.

        (b)    Forfeiture.    Absent a demonstration of immediate and heavy
financial need described above in paragraph (a), a Participant may elect to
receive 90% of his or her entire vested Account in an early distribution at any
time upon 30 days written request, in which case the remaining ten percent (10%)
of the Participant's entire vested Account shall be permanently forfeited.

        6.04    Withholding.    The Company will deduct from Plan payouts, or
from other compensation payable to a Participant or Beneficiary, amounts
required by law to be withheld for taxes with respect to benefits under this
Plan. The Company reserves the right to reduce any supplemental deferral or
contribution that would otherwise be made under this Plan on behalf of a
Participant to satisfy the Participant's tax withholding liabilities.

ARTICLE VII
SPECIAL DEFERRED COMPENSATION ARRANGEMENTS

        7.01    General.    If an Eligible Employee enters into a separate
written arrangement with the Company or an Affiliate, signed by both parties,
for the payment of nonqualified deferred compensation or the Company authorizes
the deferral of additional types of compensation arrangements (including but not
limited to severance payments, special bonuses, bonuses or other compensation
earned with a predecessor company, etc.) pursuant to a separate written
arrangement signed by the Eligible Employee and the Company or an Affiliate
(each a "Special Deferred Compensation Arrangement"), payment of such
compensation shall be made through this Plan, unless expressly specified
otherwise under such arrangement.

        7.02    Defined Contribution Arrangements.    If the Special Deferred
Compensation Arrangement is in the nature of a defined contribution arrangement,
the deferred amount will be credited to the Eligible Employee's Account when
such amounts would otherwise have been paid or when specified under the
arrangement. Amounts so credited to the Eligible Employee's Account will be
credited with

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earnings and, to the extent vested under the arrangement, shall become
distributed in accordance with the terms of the Plan, except to the extent
specified under the arrangement.

        7.03    Defined Benefit Arrangements.    If a Special Deferred
Compensation Arrangement is in the nature of a defined benefit arrangement, the
benefit shall be payable hereunder, at the time and in the form specified in the
arrangement.

ARTICLE VIII
PRIOR CCD PLAN

        This Plan shall supersede and replace the Ciba Corning Diagnostics Corp.
Supplemental Executive Retirement Plan (the "CCD SERP") effective January 1,
1998, other than with respect to Supplemental Pension Plan Benefits thereunder.
As a result, no further Supplemental Investment Plan Credits shall be made under
the CCD SERP with respect to compensation earned after December 31, 1997 and all
Supplemental Investment Plan Credits (including earnings thereon as of
December 31, 1997) attributable to compensation earned by a Participant before
January 1, 1998 shall be credited to such Participant's Account under this Plan
effective January 1, 1998 and shall be subject thereafter to this Plan's
provisions, including but not limited to this Plan's provisions relating to
earnings (for periods after December 31, 1997) and distribution. However, that
portion of an Account attributable to Supplemental Investment Plan Credits under
the CCD SERF (including earnings thereon) shall vest in the same manner that the
underlying qualified plan contributions (i.e. that they supplemented) vest under
the 401(k) Plan. If such an individual would not otherwise be a Participant in
this Plan effective January 1, 1998, he or she must elect no later than
December 31, 1997, in accordance with such procedures as the Committee shall
specify, the manner in which his or her vested Account will be paid out in
accordance with Article V of this Plan.

ARTICLE IX
MISCELLANEOUS

        9.01    Limitation of Rights.    Participation in this Plan does not
give any individual the right to be retained in the service of the Company or of
any related entity.

        9.02    Satisfaction of Claims.    Payments to a Participant, the
Participant's legal representative, or Beneficiary in accordance with the terms
of this Plan will, to the extent thereof, be in full satisfaction of all claims
that person may have hereunder against the Committee, the Company, and all
Affiliates, any of which may require, as a condition to payment, that the
recipient execute a receipt and release in a form determined by the Committee,
the Company, or an Affiliate.

        9.03    Indemnification.    The Company and the Affiliates will
indemnify and hold harmless the Directors, the members of the Committee, and
employees of the Company and the Affiliates who may be deemed fiduciaries of the
Plan, from and against any and all liabilities, claims, costs and expenses,
including attorneys' fees, arising out of an alleged breach in the performance
of their fiduciary duties under the Plan, other than such liabilities, claims,
costs and expenses as may result from the gross negligence or willful misconduct
of such persons. The Company and the Affiliates shall have the right, but not
the obligation, to conduct the defense of such persons in any proceeding to
which this Section applies.

        9.04    Assignment.    To the fullest extent permitted by law, benefits
under the Plan and rights thereto are not subject in any manner to anticipation,
alienation, sale, transfer, assignment, pledge, encumbrance, attachment, or
garnishment by creditors of a Participant or a Beneficiary.

        9.05    Inability to Locate Recipient.    If a benefit under the Plan
remains unpaid for two years from the date it becomes payable solely by reason
of the inability of the Committee to locate the Participant or Beneficiary
entitled to the payment, the benefit shall be treated as forfeited. Any amount
forfeited

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in this manner shall be restored without interest upon presentation of an
authenticated written claim by the person entitled to the benefit.

        9.06    Amendment and Termination.    The Company's Board of Directors
may, at any time, amend or terminate the Plan. In addition, the Committee may
amend the Plan (other than this Section 9.06), provided that no such amendment
may cause any substantial increase in cost to the Company or to any Affiliate.
Any amendment must be made in writing; no oral amendment will be effective. No
amendment may, without the consent of an affected Participant (or, if the
Participant is deceased, the Participant's Beneficiary), adversely affect the
Participant's or the Beneficiary's rights and obligations under the Plan with
respect to amounts already credited to a Participant's Account. Notwithstanding
the foregoing, if the Plan is terminated, the Company's Board of Directors may
determine that all Accounts will be paid out as soon as practicable thereafter
in single sum payments.

        9.07    Applicable Law.    To the extent not governed by Federal law,
the Plan is governed by the laws of the State of California. If any provision of
the Plan is held to be invalid or unenforceable, the remaining provisions of the
Plan will continue to be fully effective.

        9.08    No Funding.    The Plan constitutes a mere promise by the
Company and the Affiliates to make payments in the future in accordance with the
terms of the Plan. Except to the extent provided below in Section 9.09,
Participants and Beneficiaries have the status of general unsecured creditors of
the Company and the Affiliates and Plan benefits will be paid from the general
assets of the Company and the Affiliates and nothing in the Plan will be
construed to give any Participant or any other person rights to any specific
assets of the Company or the Affiliates. In all events, it is the intention of
the Company, all Affiliates and all Participants that the Plan be treated as
unfunded for tax purposes and for purposes of Title I of ERISA.

        9.09    Salary Deferral Trust.    Plan benefits attributable to the
supplemental salary deferrals of Participants shall be paid from the assets of a
grantor trust (the "Trust") established by the Company to assist it in meeting
its obligations and, to the extent that such assets are not sufficient, by the
Company. The Trust shall conform to the terms of the Internal Revenue Service
Model Trust as described in Internal Revenue Service Revenue Procedure 92-64.

        IN WITNESS WHEREOF, Chiron Corporation has caused this Plan, as amended
and restated effective March 1, 2003 to be executed by its duly authorized
representative on the date indicated below.

 
 
  /s/  WILLIAM G. GREEN      

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Signature   March 14, 2003

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Date

Name:   William G. Green     Title:   Sr. Vice President,
General Counsel & Secretary
   

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Exhibit 10.517

CHIRON CORPORATION SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN
ARTICLE I PURPOSE
ARTICLE II DEFINITIONS
ARTICLE III DEFERRALS AND CONTRIBUTIONS
ARTICLE IV EARNINGS
ARTICLE V VESTING
ARTICLE VI DISTRIBUTIONS
ARTICLE VII SPECIAL DEFERRED COMPENSATION ARRANGEMENTS
ARTICLE VIII PRIOR CCD PLAN
ARTICLE IX MISCELLANEOUS