Viral load differences in early infection with two HIV-1 subtypes

Objectives: Information on early HIV-1 infection has come primarily from st udies of persons infected with subtype B in North America and Europe; much less is known about other subtypes. The purpose of the present study was to compare the virologic and immunologic parameters following seroconversion among recently-infected persons infected with either of two different HIV-1 subtypes. Method: A prospective cohort study was carried out at methadone treatment c linics administered by the Bangkok Metropolitan Administration, Thailand. A total of 130 HIV-I-infected seroconverters (103 with HIV-1 subtype E and 2 7 with subtype B) were included in the study. The main outcome measures wer e serial HIV-1 RNA viral load, natural killer cell percentage, CD4 and CD8 lymphocyte counts since seroconversion. Results: The demographic and behavioral characteristics of persons with eit her subtype were similar. Median RNA viral levels at the earliest time with in 3 months of seroconversion were more than three times higher for persons infected with subtype E than subtype B (63 100 versus 18 050 copies/ml, P= 0.001). However, this difference decreased over time such that viral loads were similar at 12, 18, and 24 months following seroconversion. The CD4 an d CD8 lymphocyte counts were similar in infections with either subtype duri ng the entire period up to 24 months post-seroconversion. Conclusions: Higher viral loads associated with subtype E may result from i ntersubtype biological differences; however, the epidemiological dynamics o f transmission in Bangkok may have also contributed to this phenomenon. (C) 2001 Lippincott Williams & Wilkins.