Cerebrospinal fluid (CSF) human immunodeficiency virus (HIV) RNA levels were measured with the Nucleic Acid Sequence-Based Amplification (NASBA) assay to determine the relationship with neurological status; 37 subjects with HIV dementia (HIV-D) were compared with 77 with HIV with minor neurological signs (HIV-MCMD) and 93 neurologically normal HIV-seropositive individuals (HIV-NML). The NASBA assay had a lower limit of detection of 100 copies per milliliter. Mean CSF log HIV RNA levels were significantly higher in those with dementia after adjusting for CD4 count and were correlated with dementia severity. Plasma levels did not distinguish comparably immunosuppressed subjects with or without dementia. CSF and plasma RNA levels were significantly intercorrelated for subjects with CD4 counts <200/mm3 and also correlated inversely with CSF beta2-microglobulin. CSF RNA levels were independent of CSF pleocytosis or antiretroviral exposure. Brain RNA levels were consistently higher than CSF but correlated with CSF values for dementia subjects. The NASBA assay can be used reliably to determine HIV RNA levels in CSF, brain, and plasma samples. CSF HIV RNA may be a surrogate marker for brain infection, based on the observed correlation with brain levels. The association between plasma HIV RNA and CSF levels of HIV and beta2-microglobulin suggests that both viral load and CNS immune activation are important determinants of neurological disease.
Seminal viral load is likely to be directly related to the sexual transmissibility of human immunodeficiency virus type 1 (HIV-1). However, it is not clear whether the level of HIV-1 in semen varies with the stage of infection and whether antiretroviral therapy reduces seminal viral load. A nucleic acid sequence-based amplification (NASBA) technique was used to quantify HIV-1 RNA as an indicator of infectious viral load in semen and blood plasma of homosexual men with different stages and durations of HIV-1 infection. The median viral load in a cross section of 34 men was 11,000 HIV-1 RNA copies/ml (range, <400 to 1.3 ؋ 10 7 copies/ml) in whole semen and 5,238 HIV-1 RNA copies/ml (range, <400 to 2.8 ؋ 10 5 copies/ml) in seminal plasma, which is 10-to 1,000-fold higher than previous estimates. Viral loads in whole semen and seminal plasma were strongly correlated with blood plasma viral load (P < 0.001) but not with blood CD4 ؉ T-cell count (P ؍ 0.420). Longitudinal analysis of eight subjects who progressed to AIDS showed that seminal viral load increased in most cases, with viral load consistently higher in blood plasma than in semen. Viral loads in semen and blood plasma decreased markedly in six other patients following initiation of potent combination therapy with a protease inhibitor (indinavir) and a nonnucleoside reverse transcriptase inhibitor (DMP-266). These findings have important implications for the biology of sexual transmission of HIV-1 and its potential reduction by antiretroviral therapy.
To define the optimal blood collection parameters for plasma human immunodeficiency virus type 1 (HIV-1) viral load testing, plasma HIV-1 RNA levels were quantitated with the NASBA HIV-1 RNA QT System from blood specimens that were collected, processed, and stored under a variety of conditions that might have affected HIV-1 RNA stability. We determined that when whole blood was processed within 2 h of specimen collection the levels of HIV-1 RNA detected in EDTA-, heparin-, and acid citrate dextrose (ACD)-anticoagulated plasma samples were comparable. The levels of HIV-1 RNA in serum specimens (mean ؍ 4.126 log units) were significantly lower (P < 0.01) than the levels in corresponding plasma samples (mean ؍ 4.501 log units). One cycle of freeze-thaw (؊70°C) did not significantly reduce the level of HIV-1 RNA detected in EDTA-, heparin-, or ACD-anticoagulated plasmas. The EDTA-anticoagulated plasmas showed the smallest decrease in HIV-1 RNA copies (0.050 log units). HIV-1 RNA levels decreased over a 6-month time period in serum as well as in EDTA-, ACD-, and heparin-anticoagulated plasmas stored at ؊70°C. However, the only significant decreases were for serum (mean decrease ؍ 0.317 log units) and heparin-anticoagulated samples (mean decrease ؍ 0.384 log units). A comparison of the levels of HIV-1 RNA in cell-free plasma collected in VACUTAINER EDTA Plasma Preparation Tubes and in standard VACUTAINER EDTA tubes determined that HIV-1 RNA levels were stable for up to 30 h after collection when stored at either room temperature (mean standard deviation [SD] ؍ ؎ 0.101 log units) or at 4°C (mean SD ؍ ؎ 0.102 log units) as cell-free plasma or as EDTA-anticoagulated whole blood (mean SD ؍ ؎ 0.109 log units). These data indicate that EDTAanticoagulated plasma is the most suitable and stable matrix for HIV-1 RNA quantitation.
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