Human immunodeficiency virus type 2 (HIV-2) in Portugal: Clinical spectrum, circulating subtypes, virus isolation, and plasma viral load

The human immunodeficiency virus type 2 (HIV-2) is responsible for 4.5% of AIDS cases in Portugal. Six HIV-2 subtypes have been described so far, subt ype A being proposed as more pathogenic than the rest. The relationship bet ween the clinical status and levels of both cellular and plasma HIV-2 virae mia is not well known, nor their modifications under antiretroviral therapy . Thirty-two consecutive HIV-2 infected persons (17 men, 25 women) attendin g two different hospitals in Lisbon in 1997 were enrolled prospectively in the study. All but 4 individuals most likely acquired the infection through heterosexual contact. More than half of the study population was of Africa n origin, mainly from Guinea-Bissau. Eleven (34.4%) patients had developed clinical manifestations included within the B or C groups of the CDC classi fication system for HIV infection, with the rest being asymptomatic. Half o f the population was undergoing antiretroviral treatment at the time of the study. HIV-2 subtypes were investigated using a new Nef-based restriction fragment length polymorphism (RFLP) method that allows differentiation of t he main two variants, A and B. Plasma viral load was quantified using a new quantitative competitive reverse transcriptase polymerase chain reaction ( QcRT-PCR) procedure as well as the Amp-RT assay. Virus isolation was attemp ted from peripheral blood mononuclear cells. All but one person carried HIV -2 subtype A. Plasma viraemia examined by QcRT-PCR was measurable in 15 (50 %) of 30 subjects, yielding in all instances values below 20,000 HIV-2 RNA copies per mi. Plasma RT activity could be detected in only 10 (33%) of 30 subjects, a rate much lower than that seen in HIV-I infection. Virus was is olated from 16 (53.3%) of 30 patients. A significant correlation was found between CD4+ counts, clinical status, rate of virus isolation, and plasma v iral load by both QcRT-PCR and Amp-RT. In conclusion, HIV-2 subtype A is th e predominant variant circulating in Portugal among both natives and immigr ants. A lower cellular and plasma viral load with respect to HIV-I was seen in persons without immunosuppression, from whom the rate of virus recovery was extremely low. J. Med. Virol. 61:111-176, 2000. (C) 2000 Wiley-Liss, I nc.