Activity of HIV-1 provirus in CD4-positive T lymphocytes from patients responding well to HAART

Tsuguhiro Kaneda¹, Hiromi Nagai¹, Kaoru Wada¹, Uta Takeo¹, Junko Hattori¹, Tomoko Hagiwara¹, Shiro Ibe¹, Yukio Tawada², Makoto Utsumi¹, Takayuki Morishita³. ¹Clinical Research Center, ²Department of Clinical Laboratory, Nagoya National Hospital, 4-1-1 Sannomaru Naka-ku, Nagoya, Aichi 460-0001, Japan, and ³Department of Microbiology, Aichi Prefectural Institute of Public Health, Nagoya, Aichi, (Japan).

Background: Antiretroviral therapy has been successful in reducing plasma HIV-1 RNA to the undetectable level.  However, this therapy can not eradicate the HIV-1 provirus harboring in cells.  The aim of this study is to evaluate the potential activity level of the HIV-1 provirus remaining in the infected cells by quantifying HIV-1 DNA and mRNA copy numbers. Material and Methods: Thirty HIV-1 subtype B-infected patients with undetectable levels of plasma HIV-1 RNA (<50 copies/ml) were enrolled in this study.  CD4-positive T lymphocytes were isolated using a StemSep STS-14032 column.  The total HIV-1 DNA in the CD4-positive T lymphocytes was quantified using conventional and highly sensitive real-time PCR methods (detection limit of 5 copies/10⁶ cells).  HIV-1 mRNA was reverse-transcribed and cDNA containing the gag sequence was quantified.  The activity index was defined as the HIV-1 mRNA copy number divided by the HIV-1 DNA copy number. Results: The total HIV-1 DNA copy number ranged from <5 to 5961 copies/10⁶ cells with a median of 834 copies/10⁶ cells.  The HIV-1 mRNA copy number ranged from <5 to 72296 copies/10⁶ cells with a median of 4245 copies/10⁶ cells.  The activity index ranged from 1.2 to 92.5, and excluding one case with an index of 1726.4, the median was 8.1.  The indices of persistently infected MOLT4-IIIB and latently infected ACH2 cells were 79±6.9 and 2.2±0.4, respectively.  Nine cases had index levels lower than 4.  In contrast, four cases exhibited high levels between 92.5 and 48.6. Conclusion: The activity of HIV-1 DNA in this study ranged from the level of latently-infected cells to that of cells actively producing HIV-1.  The activity index is useful for monitoring the level of the transcriptional suppression of HIV-1 provirus in HAART responders.