Exhibit 16.1
PCAOB Letter File
Office of the Chief Accountant
Securities and Exchange Commission
100 F Street, N. E.
Washington, D. C. 20549
Gentlemen:
We have read item 4.01 of Form 8-K dated August 10, 2005, of ViroLogic, Inc. and are in agreement with the statements contained in the first sentence of the first paragraph, and the second paragraph on page two therein. We have no basis to agree or disagree with the other statements of the registrant contained therein.
/s/ Ernst & Young LLP
Palo Alto, California
August 16, 2005