Human cervicovaginal mucus contains an activity that hinders HIV-1 movement

Cervical and vaginal epithelia are primary barriers against HIV type I (HIV-1) entry during male-to-female transmission. Cervical mucus (CM) is produced by the endocervix and forms a layer locally as well as in the vaginal compartment in the form of cervicovaginal mucus (CVM). To study the potential barrier function of each mucus type during HIV-1 transmission, we quantified HIV-1 mobility in CM and CVM ex vivo using fluorescent microscopy. Virions and 200-nm PEGylated beads were digitally tracked and mean-squared displacement was calculated. The mobility of beads increased significantly in CVM compared with CM, consistent with the known decreased mucin concentration of CVM. Unexpectedly, HIV-1 diffusion was significantly hindered in the same CVM samples in which bead diffusion was unhindered. Inhibition of virus transport was envelope-independent. Our results reveal a previously unknown activity in CVM that is capable of impeding HIV-1 mobility to enhance mucosal barrier function.     

Comparison of techniques for HIV-1 RNA detection and quantitation in cervicovaginal secretions

PRINCIPLES: HIV-1 in female genital secretions has been measured using swabs, Sno Strips (Akorn, Inc., Buffalo Grove, IL), and cervicovaginal lavage (CVL), but little is known regarding the comparability of these collection techniques. METHODS: We compared HIV-1 RNA detection and quantity in specimens obtained from HIV-1-seropositive women in Kenya using three sample collection techniques and three storage techniques and evaluated reproducibility in samples collected 5 days apart. Specimens were stored in no medium, freezing medium, or TRI Reagent (Molecular Research Center, Cincinnati, OH) for 2 to 15 months. RESULTS: HIV-1 RNA assays were conducted on 640 specimens from 20 antiretroviral naive women. Storage in TRI Reagent significantly enhanced detection of genital HIV-1 and yielded significantly higher mean log10 RNA levels than specimens collected in either no or freezing medium. The prevalence of HIV-1 RNA detection in TRI Reagent ranged from 50% to 80% depending on collection method and was highest in cervical swabs. Mean log10 HIV-1 RNA levels were 3.1 log10 copies/cervical swab, 2.6 log10 copies/cervical Sno Strip, 2.5 log10 copies/vaginal swab, 2.4 log10 copies/vaginal Sno Strip, 2.9 log10 copies/ml for cervicovaginal lavage (CVL) cell pellet, and 2.1 log10 copies/ml in CVL supernatant. Comparing specimens from days 1 and 6, there was significant concordance of HIV-1 RNA detection and correlation of HIV-1 RNA levels for cervical swabs, vaginal swabs, vaginal Sno Strips, and CVL cell pellets (kappa, 0.5-0.9; r, 0.5-0.9), but not for cervical Sno Strips or CVL supernatants. CONCLUSIONS: Cervical or vaginal swab, vaginal Sno Strip, and CVL collection led to reproducible measurement of genital HIV-1 RNA, despite storage for several months and international transport. Collection using swabs was simpler than Sno Strips or cervicovaginal lavage, and yielded the highest prevalence of HIV-1 RNA detection and reproducibility.     

Quantitation of human immunodeficiency virus type 1 (HIV-1) RNA in cell-free cervicovaginal secretions: comparison of reverse transcription-PCR amplification (AMPLICOR HIV-A MONITOR 1.5) with enhanced-sensitivity branched-DNA assay (Quantiplex 3.0)

Two commercially available hypersensitive assays for human immunodeficiency virus type 1 (HIV-1) RNA quantitation, AMPLICOR HIV-1 Monitor Test 1.5 and Quantiplex HIV RNA 3.0, were compared to detect and quantify HIV-1 RNA in the cell-free fraction of cervicovaginal secretions collected by vaginal washing. Three panel specimens were used: pooled cervicovaginal secretions spiked with HIV-1 subtype A or HIV-1 subtype B and cervicovaginal lavages from HIV-positive and HIV-negative women. Compared to the AMPLICOR HIV-1 Monitor Test 1.5 assay, the Quantiplex HIV-1 3.0 assay yielded higher estimates of HIV-1 RNA concentrations in several tested samples spiked with HIV-1 RNA subtype A, as well as subtype B, particularly samples containing low amounts of HIV-1 RNA. The sensitivity and specificity of the AMPLICOR HIV-1 Monitor Test 1.5 assay were 93 and 100%, respectively; the sensitivity and specificity of the Quantiplex HIV RNA 3.0 assay were 97 and 50%, respectively. In conclusion, in quantifying HIV-1 RNA in cervicovaginal secretions, the Quantiplex HIV RNA 3.0 may lack specificity, and the AMPLICOR HIV-1 Monitor Test 1.5 assay, although highly specific, may lack sensitivity.     

Genital HIV-1 RNA predicts risk of heterosexual HIV-1 transmission

High plasma HIV-1 RNA concentrations are associated with an increased risk of HIV-1 transmission. Although plasma and genital HIV-1 RNA concentrations are correlated, no study has evaluated the relationship between genital HIV-1 RNA and the risk of heterosexual HIV-1 transmission. In a prospective study of 2521 African HIV-1 serodiscordant couples, we assessed genital HIV-1 RNA quantity and HIV-1 transmission risk. HIV-1 transmission linkage was established within the partnership by viral sequence analysis. We tested endocervical samples from 1805 women, including 46 who transmitted HIV-1 to their partner, and semen samples from 716 men, including 32 who transmitted HIV-1 to their partner. There was a correlation between genital and plasma HIV-1 RNA concentrations: For endocervical swabs, Spearman's rank correlation coefficient ρ was 0.56, and for semen, ρ was 0.55. Each 1.0 log(10) increase in genital HIV-1 RNA was associated with a 2.20-fold (for endocervical swabs: 95% confidence interval, 1.60 to 3.04) and a 1.79-fold (for semen: 95% confidence interval, 1.30 to 2.47) increased risk of HIV-1 transmission. Genital HIV-1 RNA independently predicted HIV-1 transmission risk after adjusting for plasma HIV-1 quantity (hazard ratio, 1.67 for endocervical swabs and 1.68 for semen). Seven female-to-male and four male-to-female HIV-1 transmissions (incidence <1% per year) occurred from persons with undetectable genital HIV-1 RNA, but in all 11 cases, plasma HIV-1 RNA was detected. Thus, higher genital HIV-1 RNA concentrations are associated with greater risk of heterosexual HIV-1 transmission, and this effect was independent of plasma HIV-1 concentrations. These data suggest that HIV-1 RNA in genital secretions could be used as a marker of HIV-1 sexual transmission risk.     

Quantification of genital human immunodeficiency virus type 1 (HIV-1) DNA in specimens from women with low plasma HIV-1 RNA levels typical of HIV-1 nontransmitters

Studies of human immunodeficiency virus type 1 (HIV-1) transmission suggest that genital HIV-1 RNA and DNA may both be determinants of HIV-1 infectivity. Despite its potential role in HIV-1 transmission, there are limited quantitative data on genital HIV-1 DNA. Here we validated an in-house real-time PCR method for quantification of HIV-1 DNA in genital specimens. In reactions with 100 genomes to 1 genome isolated from a cell line containing one HIV-1 provirus/cell, this real-time PCR assay is linear and agrees closely with a commercially available real-time PCR assay specific for a cellular housekeeping gene. In mock genital samples spiked with low numbers of HIV-1-infected cells such that the expected HIV-1 DNA copy number/reaction was 100, 10, or 5, the average copy number/reaction was 80.2 (standard deviation [SD], 28.3), 9.1 (SD, 5.4), or 3.1 (SD, 2.1), respectively. We used this method to examine genital HIV-1 DNA levels in specimens from women whose low plasma HIV-1 RNA levels are typical of HIV-1 nontransmitters. The median HIV-1 DNA copy number in endocervical secretions from these women (1.8 HIV-1 DNA copies/10,000 cells) was lower than that for women with higher plasma HIV-1 RNA levels (16.6 HIV-1 DNA copies/10,000 cells) (P=0.04), as was the median HIV-1 DNA copy number in vaginal secretions (undetectable versus 1.0 HIV-1 DNA copies/10,000 cells). These data suggest that women with low plasma HIV-1 RNA and thus a predicted low risk of HIV-1 transmission have low levels of genital HIV-1 cell-associated virus. The assay described here can be utilized in future efforts to examine the role of cell-associated HIV-1 in transmission.     

Increased levels of HIV-1-infected cells in endocervical secretions after the luteinizing hormone surge

Levels of HIV-1 RNA in endocervical specimens fluctuate with the menstrual cycle, suggesting that cell-free HIV-1 levels may vary during the cycle, which could influence infectivity. Here, we examined daily changes in endocervical HIV-1-infected cells during 1 cycle. There were significant positive associations between the number of days from the luteinizing hormone surge and the number of HIV-1 DNA copies/swab (P = 0.001) and the number of total cells/swab (P < 0.001) in endocervical specimens. These data suggest that sampling of cell-associated endocervical HIV-1 increases after the periovulatory period, which could result in increased exposure to HIV-1-infected cells during sexual contact.     

Use of Sno Strip filter-paper wicks for collection of genital-tract samples allows reproducible determination of human immunodeficiency virus type 1 (HIV-1) RNA viral load with a commercial HIV-1 viral load assay

To assess the reproducibility of measurements of cervical and vaginal human immunodeficiency virus (HIV) viral load, 92 duplicate cervical and 88 duplicate vaginal samples were collected from 13 HIV-infected women using Sno Strip filter-paper wicks. RNA was eluted from the strips, extracted, and assayed using a modified protocol for the Roche Cobas Amplicor HIV-1 Monitor assay. Pearson's correlation coefficient (R), coefficient of determination (D), and Bland-Altman plots (BA) were used to compare paired log10-transformed viral loads. Analysis of duplicate same-site samples showed good reproducibility (cervix: R = 0.72, D = 52%, BA = 89% within range; vagina: R = 0.72, D = 51%, BA = 87% within range); paired cervix/vagina measurements showed moderate correlation only (R = 0.56; D = 31.3%). Standardized sample collection and simple modification of the Roche Cobas Amplicor HIV-1 Monitor assay allows reproducible measurement of genital viral load.     

Analysis of HIV-1 in the cervicovaginal secretions and blood of pregnant and nonpregnant women.

OBJECTIVES: To detect HIV-1 in cellular and acellular fractions of cervicovaginal secretions obtained by cervicovaginal lavage (CVL) and evaluate viral genotypes in the HIV-1-positive CVL samples. STUDY DESIGN/METHODS: This study consists of 37 HIV-1-seropositive pregnant and nonpregnant women from the United States. A total of 63 paired CVL and blood samples were collected. HIV-1 DNA from cervical cells (CC) and virion RNA from cervical supernatant (CS) was detected by gag polymerase chain reaction (PCR) assays. The HIV-1 genotypes were determined by analyzing the nested PCR-amplified V3 region sequences of the HIV-1 gp120 envelope gene. RESULTS: Within this cohort, 95% of the women were on single or combination antiretroviral therapy. Of the pregnant women, 63% of samples had HIV-1 viral DNA in the CC, and 29% of samples were positive for viral RNA in the CS. Among nonpregnant women, 71% of samples were positive for HIV-1 DNA in CC, and 46% of samples tested positive for virion RNA in CS. Plasma viral load ranged between 10,000 and 100,000 copies/mL and showed significant correlation with the detection of HIV-1 RNA in the CVL; this relation was less apparent with viral DNA in CC. The viral blood and CVL specimens were further analyzed by evaluating the genotypes of HIV-1 variants. In most patients, a high degree of similarity was observed between the viral sequences derived from blood and CVL samples. Two patients demonstrated closely related but somewhat distinct genotypic variants in CVL and blood. One subject showed clear compartmentalization in which distinct viral genotypes were observed in CVL and blood. Based on V3 loop analyses of gp120, with one exception, the cervicovaginal secretions harbored viral populations with a macrophage (CCR5)-tropic phenotype. CONCLUSIONS: This study demonstrates the unique characteris tics of HIV-1 strains in the genital secretions of a relatively large cohort of HIV-1-infected women in the United States. These results are important for further analysis of HIV-1 transmission and pathogenesis in vivo and for rational vaccine design.     

Association between paired plasma and cervicovaginal lavage fluid HIV-1 RNA levels during 36 months

OBJECTIVE: To determine the patterns and predictors of genital tract HIV-1 RNA levels during a 36-month period. METHODS: HIV-1 RNA levels were measured blood in plasma and the genital tract (by cervicovaginal lavage [CVL]) at baseline before highly, active antiretroviral therapy, at 2 and 4 weeks and every 6 months. Viral loads were measured using nucleic acid sequence-based amplification assay with a lower limit of detection of 2.6 log10 copies/mL. RESULTS: Ninety-seven women had a median of 30.4 months' follow-up, with 530 paired PVL and CVL specimens. The strongest predictor of CVL fluid HIV-1 RNA detection was PVL of more than 2.6 log10 copies/mL, with an odds ratio of 13.7 (P < 0.0001). Each log10 unit increase in PVL increased the odds of detecting HIV-1 RNA in CVL fluid by 2.6 folds (P = 0.0002). Cervicovaginal lavage fluid HIV-1 RNA exceeded PVL on 5% of visits. When patients achieved undetectable levels of HIV-1 RNA in both plasma and CVL fluid, rebound of HIV-1 RNA occurred in plasma first or concurrently with CVL fluid HIV-1 RNA. CONCLUSIONS: Plasma viral load is the strongest predictor of CVL fluid HIV-1 RNA detection. Cervicovaginal lavage fluid HIV-1 RNA levels are generally lower than PVL. Plasma viral load is more likely to rebound first or at the same time as CVL fluid viral load.     

HIV-1 RNA in plasma and genital tract secretions in women infected with HIV-1

To assess antiretroviral therapy, all compartments, including the genital tract, need to be evaluated. HIV-1 RNA was quantified in whole cervicovaginal lavage fluid (CVL) and plasma of 56 women and in the cellular and supernatant fractions of 27 of these women. Overall, we detected HIV-1 RNA in 59% of whole CVL samples and in 61% and 44% of cellular and supernatant fractions of the subset of women, respectively. Detectability of HIV-1 RNA in CVL increased with increasing level of plasma RNA in both unfractionated and cell-associated CVL components (p = .0004 and .002, respectively), but not in the cell-free fraction (p = .29). Mean HIV-1 RNA levels in CVL increased with decreasing CD4 counts (p = .002,) and with increasing plasma HIV-1 RNA (p < .001). Adjusted odds ratios (OR) for detectable CVL RNA were highest for women with CD4 counts <200 cells/mm3 (OR, 10.1; 95% confidence interval [CI]: 1.6-82.7; p = .02) and >50,000 copies/ml of plasma RNA (OR, 25.2; 95% CI, 3.2-554; p = .01). Treatment did not seem to affect RNA detection in CVL after adjusting for plasma RNA and CD4. In conclusion, we found that detectability and level of CVL RNA were closely associated with the cellular fraction of genital secretions in women and strongly correlated with the level of plasma RNA and CD4. Genital tract secretions may need to be tested in the assessment of treatment efficacy and this can easily be accomplished with this rapid and easy procedure using whole CVL.     

Detection and quantitation of human immunodeficiency virus type 1 in the female genital tract. The Division of AIDS Treatment Research Initiative 009 Study Group

Human immunodeficiency virus type 1 (HIV-1) was detected in the genital tracts of 59% of 225 women by RNA PCR and in 7% of the women by culture. In a comparison of two sampling methods, endocervical swabs were more sensitive than cervicovaginal lavage for HIV-1 RNA detection by PCR but not by culture and their sensitivity was independent of the concentration of HIV-1 RNA.     

Differences in HIV-1 pol sequences from female genital tract and blood during antiretroviral therapy

OBJECTIVE: To determine whether HIV-1 replicates locally in the female genital tract during therapy, and to study whether endocervix is the dominant source of virus in cervicovaginal lavage fluid. DESIGN: Sequence analyses of HIV-1 pol were performed from cervicovaginal secretions and blood plasma of HIV-infected women failing antiretroviral therapy with detectable viral load in both compartments, as well as from drug-naive subjects. METHODS: Viral RNA was extracted from cervicovaginal lavage fluid, endocervical secretions collected by Sno-strips, and blood plasma. Population sequencing of HIV-1 pol was performed using cycle sequencing. Drug resistance mutations were analyzed. Phylogenies were constructed based on synonymous positions in the sequences. RESULTS: Resistant virus was detected concordantly in blood and genital tract specimens, consistent with drug selection pressure in both compartments. However, drug-selected mutations often differed in each compartment, and phylogenetic analysis showed differences in virus lineage in these compartments, consistent with local replication in female genital tract. Viruses in cervicovaginal lavage and endocervical secretions were genetically distinguishable, suggesting that endocervix is not the only source of virus found in cervicovaginal lavage. CONCLUSION: These data support the hypothesis that HIV replication is compartmentalized within the female genital tract during antiretroviral therapy, which has implications for pathogenesis and for epidemiologic surveillance of drug-resistant virus.     

Higher HIV-1 RNA cutoff level required in cerebrospinal fluid than in blood to predict positive HIV-1 isolation

HIV-1 can be isolated from the vast majority of blood samples taken from HIV-1-seropositive patients not treated with antiretroviral drugs. Isolation rates from cerebrospinal fluid (CSF) samples are considerably lower, ranging between 20-70%. The objective of this study was to determine the cutoff levels for HIV-1 RNA that would yield a positive predictive value > or =90% for positive virus isolation from CSF and blood. Quantitative HIV-1 RNA PCR (Amplicor HIV monitor, version 1.0, Roche Diagnostic Systems) and virus isolation were used to examine 303 CSF samples and 278 paired blood samples from 157 HIV-1-seropositive patients. Patients on antiretroviral treatment provided 140 of the CSF samples and 131 of the blood samples. CSF samples that were positive by culture numbered 137 of 303 (45%), as compared with 216 of 278 (78%) blood samples. In the case of samples taken from patients with antiretroviral treatment, 28% were positive by culture from CSF and 63% from blood. As expected, mean HIV-1 RNA levels were higher in CSF and blood samples positive by culture than in samples negative by culture. A cutoff level of >5,000 HIV-1 RNA copies/ml was required to yield a positive predictive value for positive virus isolation from CSF samples of > or =90%, whereas the cutoff level for blood samples was just above the detection limit of the assay (>200 HIV-1 copies/ml).     

Influence of storage temperature on the stability of HIV-1 RNA and HSV-2 DNA in cervicovaginal secretions collected by vaginal washing

Variability in the handling of samples of genital secretions prior to quantitation of HIV-1 RNA and HSV DNA may profoundly affect both the detection and quantitation of these nucleic acids. Over 144 h, we evaluated, the influence of storage temperature (4 degrees C, 20 degrees C, 30 degrees C) on the quantity of HIV-1 RNA and HSV-2 DNA in HIV and HSV negative cervicovaginal lavage pools spiked with known amounts of HIV-1 and HSV-2 and in HIV-1 and HSV-2 co-infected cervicovaginal lavage pools. The level of viral nucleic acids remained stable at 4 degrees C for 24h but decreased significantly when cervicovaginal lavages were stored at 20 degrees C and 30 degrees C, demonstrating that, cervicovaginal lavages to be quantified for viral RNA or DNA require, at minimum, immediate storage at 4 degrees C.     

Detection of human immunodeficiency virus type 1 (HIV-1) in heel prick blood on filter paper from children born to HIV-1-seropositive mothers.

The human immunodeficiency virus type 1 (HIV-1) DNA PCR results of 94 dried blood spot (DBS) samples on filter paper and corresponding venous blood in EDTA obtained from infants born to HIV-1-seropositive mothers were compared. In addition, the results of HIV-1 DNA PCR on DBS and the HIV-1 RNA PCR from plasma of 70 paired samples were compared. A 100% specificity and a 95% sensitivity for HIV-1 DNA PCR on DBS compared with results for venous blood were observed for the 94 paired samples. The results of the DBS HIV-1 DNA PCR and HIV-1 RNA PCR of 70 corresponding plasma samples correlated perfectly (100%). The DBS HIV-1 DNA PCR method proved reliable for HIV-1 detection.     

Evaluation of the Abbott Real-Time HIV-1 quantitative assay with dried blood spot specimens

The Abbott Real-Time HIV-1 assay was evaluated for its performance in quantification of human immunodeficiency virus type 1 (HIV-1) RNA in dried blood spot (DBS) samples. In total, 169 blood samples with detectable plasma HIV-1 RNA were used to extract RNA from paired DBS and liquid plasma samples, using the automated Abbott m Sample Preparation System (m2000sp). HIV-1 RNA was then quantitated by the m2000rt RealTime analyser. RNA samples suitable for real-time PCR were obtained from all but one (99.4%) of the DBS samples and HIV-1 RNA was detected in 163/168 (97.0%) samples. The correlation between HIV-1 RNA values measured in paired DBS and plasma samples was very high ( r  = 0.882), with 78.5% and 99.4% of cases differing by <0.5 and 1.0 log, respectively. Retesting of DBS replicates following 6 months of storage at 2–8°C showed no loss of HIV-1 RNA in a subset of 89 samples. The feasibility of DBS testing coupled with automated sample processing, and the use of a latest-generation FDA-approved real-time PCR-based system, represents an encouraging first step for viral load measurement in reference centres in developing countries where access to antiretroviral therapy is expanding.     

Micronutrient supplementation increases genital tract shedding of HIV-1 in women: results of a randomized trial

To test the hypothesis that micronutrient supplementation decreases genital HIV-1 shedding, a double-blind, randomized, placebo-controlled trial of 6 weeks of multivitamin plus selenium supplementation vs. placebo was conducted among 400 HIV-1-seropositive, nonpregnant, antiretroviral-naive women in Mombasa, Kenya. Primary outcome measures included cervical and vaginal shedding of HIV-1-infected cells and RNA. Secondary outcomes included plasma viral load and CD4 count. Surprisingly, the odds of detection of vaginal HIV-1-infected cells were 2.5-fold higher (P = 0.001) and the quantity of HIV-1 RNA in vaginal secretions was 0.37 log10 copies/swab higher (P = 0.004) among women who received micronutrients in comparison to placebo, even after adjustment for potential confounders including baseline HIV-1 shedding and CD4 count. The increase in vaginal HIV-1 shedding was greatest among women who had normal baseline selenium levels. Micronutrient supplementation resulted in higher CD4 (+23 cells/microL, P = 0.03) and CD8 (+74 cells/microL, P = 0.005) counts compared with placebo but did not alter the plasma viral load. In this randomized trial, micronutrients resulted in higher levels of genital HIV-1 shedding compared with placebo. The potential benefit of micronutrient supplementation in HIV-1-seropositive women should be considered in relation to the potential for increased infectivity.