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.