|CONFIDENTIAL |  | REDACTED VERSION
|------------ |  | ----------------

[***]
CERTAIN INFORMATION IN THIS EXHIBIT HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE
OMITTED PORTIONS.

TERM SHEET

This binding Term Sheet sets forth the agreement of Chiron Corporation ("Chiron"), on the one hand, and F. Hoffmann-La Roche Ltd. and Roche
Molecular Systems, Inc. (collectively, "Roche"), on the other, with respect to the settlement of their current arbitration relating to royalties ("Arbitration"), through amendment of the HIV
Probe License Agreement by and between the parties effective as of October 10, 2000 ("Clinical Diagnostics Agreement") and the Blood Screening HIV Probe License Agreement by and between the
parties effective as of January 1, 2001 ("Blood Screening Agreement," collectively with the Clinical Diagnostics Agreement, the "Agreements"). Terms not defined in this Term Sheet have the
meanings given to them in the applicable Agreement. This Term Sheet shall become effective as of September 3, 2004.

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AGREED
TO AND ACCEPTED BY:

Chiron
Corporation

|By:                           |  | /s/JEKENT                |  | 
|----------------------------- |  | ------------------------ |  | 
|Date:                         |  | Sept. 3, 2004            |  | 
|AGREED TO AND ACCEPTED BY:   
|F. Hoffmann-La Roche Ltd.    
|By:                           |  | /s/HEINO VON PRONDZYNSKI |  | 
|                              |  | /s/ROBERT YATES          |  | 
|Date:                         |  | 3 Sept 04                |  | 
|AGREED TO AND ACCEPTED BY:   
|Roche Molecular Systems, Inc.
|By:                           |  | /s/H. DREISMANN          |  | 
|Date:                         |  | September 3, 2004        |  | 

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EXHIBIT A  before The honorable  Charles B. Renfrew, arbitrator

|IN THE MATTER OF THE ARBITRATION
BETWEEN
CHIRON CORPORATION,
Claimant
AND
ROCHE MOLECULAR SYSTEMS, INC.,
Respondent |  | STIPULATED ARBITRATION AWARD
|------------------------------------------------------------------------------------------------------------------- |  | ----------------------------

Stipulation

Chiron
Corporation and Roche Molecular Systems, Inc., on behalf of themselves and their affiliates, hereby irrevocably stipulate as follows:

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|Date: August    , 2004 |  | Agreed:                                                                                                           | 
|---------------------- |  | ----------------------------------------------------------------------------------------------------------------- | 
|                       |  |                                                                                                                   | 
|                       |  | Stephen S. Rabinowitz
FRIED, FRANK, HARRIS, SHRIVER & JACOBSON LLP                                               
|                       |  | Charles B. Cohler
PAUL, HASTINGS, JANOFSKY & WALKER LLP                                                          
|                       |  | Attorneys for Roche Molecular Systems, Inc.                                                                      
|Date: August    , 2004 |  | Agreed:                                                                                                           | 
|                       |  |                                                                                                                   | 
|                       |  | Rachel Krevans
Mathew I. Kreeger
Wesley E. Overson
Lawrence B. Berroya
Peter P. Meringolo
MORRISON & FOERSTER LLP
|                       |  | Attorneys for Chiron Corporation                                                                                 

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IT
IS SO ORDERED.

|By:   | Hon. Charles B. Renfrew, Arbitrator |  | 
|----- | ----------------------------------- |  | 
|Date: |                                     |  | 

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EXHIBIT B  before The honorable  Charles B. Renfrew, arbitrator

|IN THE MATTER OF THE ARBITRATION
BETWEEN
CHIRON CORPORATION,
Claimant
AND
ROCHE MOLECULAR SYSTEMS, INC.,
Respondent |  | RENEWED STIPULATED RE DELAYED RENDERING OF AWARD
|------------------------------------------------------------------------------------------------------------------- |  | ------------------------------------------------

Stipulation

Chiron
Corporation and Roche Molecular Systems, Inc., on behalf of themselves and their affiliates, jointly agree and stipulate as follows:

Notwithstanding
Section 9(d)(12) of Settlement Agreement by and between the parties effective as of October 10, 2000, which requires that the Arbitrator render an award in this
Arbitration together with a decision on the award in writing ("Award") within seven calendar days following the submission of post-hearing briefs, the parties jointly request that the
Arbitrator not render the Award prior to September 14, 2004, at 4:00 p.m.

|Date: August    , 2004 |  | Agreed:                                                                                                           | 
|---------------------- |  | ----------------------------------------------------------------------------------------------------------------- | 
|                       |  |                                                                                                                   | 
|                       |  | Stephen S. Rabinowitz
FRIED, FRANK, HARRIS, SHRIVER & JACOBSON LLP                                               
|                       |  | Charles B. Cohler
PAUL, HASTINGS, JANOFSKY & WALKER LLP                                                          
|                       |  | Attorneys for Roche Molecular Systems, Inc.                                                                      
|Date: August    , 2004 |  | Agreed:                                                                                                           | 
|                       |  |                                                                                                                   | 
|                       |  | Rachel Krevans
Mathew I. Kreeger
Wesley E. Overson
Lawrence B. Berroya
Peter P. Meringolo
MORRISON & FOERSTER LLP
|                       |  | Attorneys for Chiron Corporation                                                                                 

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EXHIBIT C    REFUND SCHEDULE AND ADJUSTED ROYALTY RATES

|Refund
Request
Date |  | Refund
Amount:
Clinical
Diagnostics
(MM) |       | Refund
Amount:
Blood
Screening
(MM) |   | Clinical
Diagnostics
Earned
Royalty
Rate |  | Minimum
Amount/Test:
HIV Qualitative
Assay |   | Minimum
Amount/Test:
HIV Quantitative
Assay |       | Earned
Royalty
Amount:
Blood
Screening |   | Earned
Royalty
Amount:
Plasma
Fractation
|------------------- |  | ---------------------------------------- | ----- | ----------------------------------- | - | ---------------------------------------- |  | ------------------------------------------ | - | ------------------------------------------- | ----- | -------------------------------------- | - | ----------------------------------------
|2/1/05              |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   
|3/31/05             |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   
|6/30/05             |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   
|9/30/05             |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   
|12/31/05            |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   
|3/31/06             |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   
|6/30/06             |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   
|10/2/06             |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   
|12/31/06            |  | $                                        | [***] |                                     | $ | [***]                                    |  | [***]                                      | % | $                                           | [***] |                                        | $ | [***]                                   

[***]
CERTAIN INFORMATION IN THIS EXHIBIT HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE
OMITTED PORTIONS.

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