SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* BB BIOVENTURES L P (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Pharmasset Inc [ VRUS ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 05/02/2007
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/02/2007		X		254,906(5)	A	$0.15	2,858,150	I	See Footnote(1)
Common Stock	05/02/2007		F		4,245(2)	D	$9	2,853,905	I	See Footnote(3)
Common Stock	05/02/2007		C		245,331(8)	A	(7)	3,099,236	I	See Footnote(10)
Common Stock	05/02/2007		C		717,487(11)	A	(7)	3,816,723	I	See Footnote(12)
Common Stock	05/02/2007		P		277,777(13)	A	$9	4,094,500	I	See Footnote(14)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Warrant to purchase Series D-1 Preferred Stock	$0.1(6)	05/02/2007		X			382,365	(4)	(4)	Common Stock	254,906(5)	$0	0	I	See Footnote(9)
Series B Preferred Stock	(6)	05/02/2007		C			367,999	(7)	(7)	Common Stock	245,331(8)	$0	0	I	See Footnote(9)
Series D Preferred Stock	(6)	05/02/2007		C			1,076,231	(7)	(7)	Common Stock	717,487(11)	$0	0	I	See Footnote(9)

1. Name and Address of Reporting Person* BB BIOVENTURES L P (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* BAB BIO VENTURES LLP (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* BAB BIO VENTURES NV (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM ASSET MANAGEMENT INVESTORS 1999 LLC (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM BIOVENTURES PARALLEL FUND L P (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM BIOVENTURES I LP (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM BIO VENTURES I LLC (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* EVNIN LUKE (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* STEINMETZ MICHAEL (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. These shares are held as follows: 1,578,034 shares by BB BioVentures, L.P. ("BBBV"), 214,771 shares by MPM BioVentures Parallel Fund, L.P. ("BV PF"), 18,841 shares by MPM Asset Management Investors 1999 LLC ("AM 1999"), 58,362 shares by MPM BioVentures III, L.P., ("BV III"), 867,946 shares by MPM BioVentures III-QP, L.P. ("BV III QP"), 73,349 shares held by MPM BioVentures III GmbH & Co. Beteiligungs KG ("BV KG"), 26,214 shares by MPM BioVentures III Parallel Fund, L.P. ("BV III PF") and 20,633 shares held by MPM Asset Management Investors 2004 BVIII LLC ("AM BV III"). MPM BioVentures I, L.P. ("BV I") and MPM BioVentures I LLC ("BV I LLC") are the direct and indirect general partners of BV PF. BAB BioVentures L.P. ("BAB BV"), BAB BioVentures, N.V. ("BAB NV") and BV I LLC are the direct and indirect general partners of BB BV. Luke Evnin and Michael Steinmetz are managers of AM 1999 and BV I LLC. MPM BioVentures III GP, L.P. ("BV III GP") and MPM BioVentures III LLC ("BV III LLC") are the direct and indirect general partners of BV III, BV III QP, BV III PF and BV KG. Luke Evnin and Michael Steinmetz are members of BV III LLC and AM BV III. Each member of the group disclaims beneficial ownership of all such shares except to the extent of their respective proportionate pecuniary interests therein.

2. The shares were net exercised and disposed of as follows: 580 by BBBV, 66 by BV PF, 7 by AM 1999, 199 by BV III, 2,981 by BV III QP, 252 by BV KG, 90 by BV III PF and 70 by AM BV III.

3. The shares are held as follows: 1,577,454 by BBBV, 214,705 by BV PF, 18,834 by AM 1999, 58,163 by BV III, 864,965 by BV III QP, 73,097 by BV KG, 26,124 by BV III PF and 20,563 by AM BV III. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.

4. Immediately exercisable. These warrants shall expire upon the closing of the Issuer's initial public offering.

5. The warrants are held as follows: 34,858 by BBBV, 3,957 by BV PF, 408 by AM 1999, 12,028 by BV III, 178,884 by BV III QP, 15,117 by BV KG, 5,402 by BV III PF and 4,252 by AM BV III.

6. Each share of Preferred Stock automatically converted into shares of Common Stock on a .666667 for 1 basis immediately prior to the closing of the Issuer's initial public offering.

7. These securities are preferred stock of the Issuer and do not have an expiration date. These securities automatically converted into shares of common stock upon the closing of the Issuer's initial public offering.

8. The shares are held as follows: 213,758 by BBBV, 29,022 by BV PF, 2,551 by AM 1999.

9. No securities owned.

10. The shares are held as follows: 1,791,212 by BBBV, 243,727 by BV PF, 21,385 by AM 1999, 58,163 by BV III, 864,965 by BV III QP, 73,097 by BV KG, 26,124 by BV III PF and 20,563 by AM BV III. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.

11. The shares are held as follows: 98,115 by BBBV, 11,139 by BV PF, 1,148 by AM 1999, 33,857 by BV III, 503,500 by BV III QP, 42,551 by BV KG, 15,207 by BV III PF and 11,970 by AM BV III.

12. The shares are held as follows: 1,889,327 by BBBV, 254,866 by BV PF, 22,533 by AM 1999, 92,020 by BV III, 1,368,465 by BV III QP, 115,648 by BV KG, 41,331 by BV III PF and 32,533 by AM BV III. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.

13. The shares were purchased as follows: 15,492 by BV III, 230,381 by BV III QP, 19,469 by BV KG, 6,958 by BV III PF and 5,477 by AM BV III.

14. The shares are held as follows: 1,889,327 by BBBV, 254,866 by BV PF, 22,533 by AM 1999, 107,512 by BV III, 1,598,846 by BV III QP, 135,117 by BV KG, 48,289 by BV III PF and 38,010 by AM BV III. Each member of the group disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.

	By Ansbert Gadicke, managing director of BAB BioVentures NV, the general partner of BAB BioVentures L.P., the general partner of BB BioVentures L.P. /s/ Ansbert Gadicke	05/04/2007
	By Ansbert Gadicke, managing director of BAB BioVentures NV, the general partner of BAB BioVentures L.P. /s/ Ansbert Gadicke	05/04/2007
	By Ansbert Gadicke, managing director of BAB BioVentures NV /s/ Ansbert Gadicke	05/04/2007
	By Luke Evnin, manager of MPM Asset Management Investors 1999 LLC /s/ Luke Evnin	05/04/2007
	By Luke Evnin, manager of MPM BioVentures I LLC, the general partner of MPM BioVentures I L.P., the general partner of MPM BioVentures Parallel Fund, L.P. /s/ Luke Evnin	05/04/2007
	By Luke Evnin, manager of MPM BioVentures I LLC, the general partner of MPM BioVentures I L.P. /s/ Luke Evnin	05/04/2007
	By Luke Evnin, manager of MPM BioVentures I LLC /s/ Luke Evnin	05/04/2007
	/s/ Luke Evnin	05/04/2007
	/s/ Michael Steinmetz	05/04/2007
	** Signature of Reporting Person	Date
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