Objective: The OraQuick Advance Rapid HIV-1/2 Test is a point-of-care test capable of detecting HIV-specific antibodies in blood and oral fluid. To understand test performance and factors contributing to false-negative (FN) results in longitudinal studies, we examined results of participants enrolled in the TDF2 study, the Bangkok Tenofovir Study, and the Bangkok MSM Cohort Study (BMCS), three separate clinical studies of high-risk, HIV-negative persons conducted in Botswana and Thailand. Design: Retrospective observational analysis. Methods: We compared oral fluid OraQuick (OFOQ) results among participants becoming HIV-infected to results obtained retrospectively using enzyme immunoassay and nucleic acid amplification tests on stored specimens. We categorized negative OFOQ results as true-negative or false-negative relative to NAAT and/or EIA, and determined the delay in OFOQ conversion relative to the estimated time of infection. We used generalized estimating equations to examine the association between FN results and participant, clinical and testing-site factors. Results: Two-hundred and thirty-three FN OFOQ results occurred in 80 of 287 seroconverting individuals. Estimated OFOQ conversion delay ranged from 14.5-547.5 (median 98.5) days. Delayed OFOQ conversion was associated with clinical site and test operator (p<0.05), pre-exposure prophylaxis (p=0.01), low plasma viral load (p<0.02) and time to kit expiration (p<0.01). Participant age, gender, and HIV subtype were not associated with FN results. Long OFOQ conversion delay time was associated with antiretroviral exposure and low PVL. Conclusions: Failure of OFOQ to detect HIV-1 infection was frequent, and multifactorial in origin. In longitudinal trials, negative oral fluid results should be confirmed by testing blood samples.

Successful clinical trials of antiretroviral pre-exposure prophylaxis (PrEP) to prevent HIV infection have been reported in heterosexual men and women, men who have sex with men (MSM), and injection drug users1. A daily oral drug regimen containing nucleoside reverse transcriptase inhibitors (NRTIs) tenofovir disoproxil fumarate (TDF) alone or in combination with emtricitabine (FTC) have been effective when participant adherence is high1. Analysis of PrEP dosing patterns estimate taking at least four TDF doses per week provides 96% protection from HIV infection and at least two doses per week provides 76% protection in MSM and transgender women2, though some estimate more frequent dosing in heterosexual women may be needed3. TDF and FTC require phosphorylation in HIV target cells to tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP) to provide PrEP protection as competitive analogs of naturally occurring deoxyadenosine triphosphate (dATP) and deoxycytidine triphosphate (dCTP), respectively. However, it is unclear if physiological conditions that increase dNTP concentrations can affect pharmacokinetics (PK) and pharmacodynamics (PD) of NRTIs. This may be particularly relevant when cellular deoxynucleoside triphosphate (dNTP) pools in HIV target cells increase in response to immune activation. Decreased ratios of phosphorylated NRTIs to their respective dNTPs have been associated with cell activation in vitro and in nonhuman primate studies4,5, yet this observation remains unexplored in PK and PD studies that measured intracellular drug6-8. The study presented here compared dATP and dCTP concentrations to TFV-DP and FTC-TP in peripheral blood mononuclear cell (PBMCs) of persons using daily oral Truvada™ during a successful HIV PrEP study. We further examined if variations among intracellular drug:dNTP ratios were related to lymphocyte activation.

INTRODUCTION: Accurate clinical laboratory reference values derived from a local or regional population base are required to correctly interpret laboratory results. In Botswana, most reference intervals used to date are not standardized across clinical laboratories and are based on values derived from populations in the United States or Western Europe. METHODS: We measured 14 hematologic and biochemical parameters of healthy young adults screened for participation in the Botswana HIV Pre-exposure Prophylaxis Study using tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) (TDF2 Study). Reference intervals were calculated using standard methods, stratified by gender, and compared with the site-derived reference values used for the TDF2 study (BOTUSA ranges), the Division of AIDS (DAIDS) Grading Table for Adverse Events, the Botswana public health laboratories, and other regional references. RESULTS: Out of 2533 screened participants, 1786 met eligibility criteria for participation in study and were included in the analysis. Our reference values were comparable to those of the Botswana public health system except for amylase, blood urea nitrogen (BUN), phosphate, total and direct bilirubin. Compared to our reference values, BOTUSA reference ranges would have classified participants as out of range for some analytes, with amylase (50.8%) and creatinine (32.0%) producing the highest out of range values. Applying the DAIDS toxicity grading system to the values would have resulted in 45 and 18 participants as having severe or life threatening values for amylase and hemoglobin, respectively. CONCLUSION: Our reference values illustrate the differences in hematological and biochemical analyte ranges between African and Western populations. Thus, the use of western-derived reference laboratory values to screen a group of Batswana adults resulted in many healthy people being classified as having out-of-range blood analytes. The need to establish accurate local or regional reference values is apparent and we hope our results can be used to that end in Botswana.

BACKGROUND: Tenofovir-emtricitabine (TDF-FTC) pre-exposure prophylaxis (PrEP) has been found to be effective for prevention of HIV infection in several clinical trials. Two studies of TDF PrEP among men who have sex with men showed slight bone mineral density (BMD) loss. We investigated the effect of TDF and the interaction of TDF and hormonal contraception on BMD among HIV-uninfected African men and women. METHOD: We evaluated the effects on BMD of using daily oral TDF-FTC compared to placebo among heterosexual men and women aged 18-29 years enrolled in the Botswana TDF2 PrEP study. Participants had BMD measurements at baseline and thereafter at 6-month intervals with dual-energy X-ray absorptiometry (DXA) scans at the hip, spine, and forearm. RESULTS: A total of 220 participants (108 TDF-FTC, 112 placebo) had baseline DXA BMD measurements at three anatomic sites. Fifteen (6.8%) participants had low baseline BMD (z-score of <-2.0 at any anatomic site), including 3/114 women (2.6%) and 12/106 men (11.3%) (p = 0.02). Low baseline BMD was associated with being underweight (p = 0.02), having high blood urea nitrogen (p = 0.02) or high alkaline phosphatase (p = 0.03), and low creatinine clearance (p = 0.04). BMD losses of >3.0% at any anatomic site at any time after baseline were significantly greater for the TDF-FTC treatment group [34/68 (50.0%) TDF-FTC vs. 26/79 (32.9%) placebo; p = 0.04]. There was a small but significant difference in the mean percent change in BMD from baseline for TDF-FTC versus placebo at all three sites at month 30 [forearm -0.84% (p = 0.01), spine -1.62% (p = 0.0002), hip -1.51% (p = 0.003)]. CONCLUSION: Use of TDF-FTC was associated with a small but statistically significant decrease in BMD at the forearm, hip and lumbar spine. A high percentage (6.8%) of healthy Batswana young adults had abnormal baseline BMD. Further evaluation is needed of the longer-term use of TDF in HIV-uninfected persons. TRIAL REGISTRATION: ClinicalTrials.gov NCT00448669.

We examined CD4 cell count and plasma viral load patterns among Botswana TDF/FTC Oral HIV Prophylaxis Trial (TDF2 study) participants who seroconverted, comparing participants assigned to receive tenofovir/emtricitabine with participants assigned to receive placebo. We also evaluated for antiretroviral drug resistance among the breakthrough HIV infections. Among nine seroconverters assigned to tenofovir/emtricitabine and 24 to placebo, there were no significant differences in their CD4 cell count or viral load profiles over time. Of the four participants who seroconverted on-study while receiving tenofovir/emtricitabine, none became infected as a result of drug-resistant HIV; moreover, no resistance mutations emerged following seroconversion.

BACKGROUND: Preexposure prophylaxis with antiretroviral agents has been shown to reduce the transmission of human immunodeficiency virus (HIV) among men who have sex with men; however, the efficacy among heterosexuals is uncertain. METHODS: We randomly assigned HIV-seronegative men and women to receive either tenofovir disoproxil fumarate and emtricitabine (TDF-FTC) or matching placebo once daily. Monthly study visits were scheduled, and participants received a comprehensive package of prevention services, including HIV testing, counseling on adherence to medication, management of sexually transmitted infections, monitoring for adverse events, and individualized counseling on risk reduction; bone mineral density testing was performed semiannually in a subgroup of participants. RESULTS: A total of 1219 men and women underwent randomization (45.7% women) and were followed for 1563 person-years (median, 1.1 years; maximum, 3.7 years). Because of low retention and logistic limitations, we concluded the study early and followed enrolled participants through an orderly study closure rather than expanding enrollment. The TDF-FTC group had higher rates of nausea (18.5% vs. 7.1%, P<0.001), vomiting (11.3% vs. 7.1%, P=0.008), and dizziness (15.1% vs. 11.0%, P=0.03) than the placebo group, but the rates of serious adverse events were similar (P=0.90). Participants who received TDF-FTC, as compared with those who received placebo, had a significant decline in bone mineral density. K65R, M184V, and A62V resistance mutations developed in 1 participant in the TDF-FTC group who had had an unrecognized acute HIV infection at enrollment. In a modified intention-to-treat analysis that included the 33 participants who became infected during the study (9 in the TDF-FTC group and 24 in the placebo group; 1.2 and 3.1 infections per 100 person-years, respectively), the efficacy of TDF-FTC was 62.2% (95% confidence interval, 21.5 to 83.4; P=0.03). CONCLUSIONS: Daily TDF-FTC prophylaxis prevented HIV infection in sexually active heterosexual adults. The long-term safety of daily TDF-FTC prophylaxis, including the effect on bone mineral density, remains unknown. (Funded by the Centers for Disease Control and Prevention and the National Institutes of Health; TDF2 ClinicalTrials.gov number, NCT00448669 .).