[1] Johns Hopkins Med Inst, Dept Pathol, Baltimore, MD 21205 USA
[2] Celera Diagnost, Alameda, CA 94502 USA
[3] Abbott Labs, AIDS Res & Retrovirus Discovery, Abbott Pk, IL 60064 USA
[4] ViroLog Inc, San Francisco, CA 94080 USA
[5] St George Hosp, Courtyard Clin, London, England