Virologic measurements are increasingly used to evaluate prognosis and treatment responses in human immunodeficiency virus (HIV) type 1 infection. Markers of HIV-1 replication, including infectious HIV-1 titer from peripheral blood mononuclear cells, serum HIV-1 p24 antigen, plasma HIV-1 RNA, CD4 cell numbers, and viral syncytium-inducing (SI) phenotype, were determined in 391 virology substudy participants in AIDS Clinical Trials Group study 175. The subjects had 200-500 CD4 cells/mm3. All markers of viral replication significantly correlated with one another and were inversely related to CD4 cell number. Disease progression to an AIDS-defining event or death or loss of >50% of CD4 cells was associated with infectious HIV-1 titer (P < .001), HIV-1 RNA (P < .001), and HIV-1 p24 antigen (P = .007). In multivariate proportional hazards models, p24 antigen was never significant when HIV-1 RNA level was included. In a model containing infectious HIV-1 titer (P = .038), HIV-1 RNA (P < .001), SI phenotype (P < .001), and CD4 cell number (P = .18), only the virologic parameters remained significantly associated with progression.
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Received 20 May 1997; revised 29 September 1997. Presented in part: 4th Conference on Retroviruses and Opportunistic Infections, Washington, DC, January 1997 (abstract 543). Informed consent was obtained from all study participants. The study followed the human experimentation guidelines of the US Department of Health and Human Services. Grant support: NIH: AI-27670, AI-38858, and AI-36214 (to J.L.L.); AI-25868, VC-006, and RR-00046 (to S.A.F.); AI-65304 (to J.B.J.); AI-27658 and RR-0004 (to R.R.); AI-27659 and AI-29193 (to R.D.); and AI-27560 (to W.S.). Reprints or correspondence: Dr. Janet L. Lathey, Dept. of Pediatrics, University of California, San Diego, 9500 Gilman Dr., #0672, La Jolla, CA 92093-0672 (email@example.com). * Present affiliation: Abbott Laboratories, Abbott Park, Illinois.