Evaluation of Xpert point-of-care assays for detection of HIV infection in persons using long-acting cabotegravir for pre-exposure prophylaxis.

Detection of HIV infection may be challenging in persons using long-acting cabotegravir (CAB-LA) pre-exposure prophylaxis (PrEP) due to viral suppression and reduced/delayed antibody production. We evaluated two point-of-care tests for detecting HIV infection in persons who received CAB-LA in the HPTN 083 trial. Samples were obtained from 12 participants who received CAB-LA and had delayed detection of HIV infection using HIV rapid tests and an antigen/antibody test (52 plasma samples; 18 dried blood spot [DBS] samples). Plasma samples were tested with the Xpert HIV-1 Viral Load XC test (Xpert VL-XC); DBS samples were tested with the total nucleic acid Xpert HIV-1 Qual XC test (Xpert Qual-XC). Results from these assays were compared to results from three reference, laboratory-based, plasma RNA assays (Aptima HIV-1 Qualitative assay [Aptima Qual]; Aptima HIV-1 Quant DX Assay [Aptima Quant]; cobas HIV-1/HIV-2 Qualitative Test [cobas]). HIV RNA was detected with all four plasma assays for all samples with viral loads (VLs) ≥ 200 copies/mL; the number of samples with VLs < 200 copies/mL with HIV RNA detected was: Xpert VL-XC: 19/26 (73.1%); Aptima Qual: 17/26 (65.4%); Aptima Quant: 17/26 (65.4%); and cobas: 12/21 (57.1%). The Xpert Qual-XC assay was positive for all DBS samples with VLs ≥ 200 copies/mL and 1/10 DBS with VLs < 200 copies/mL. The performance of the Xpert VL-XC assay was comparable to the reference assays for detecting HIV infection in these cases. The Xpert Qual-XC assay was less sensitive than plasma-based HIV RNA assays for detecting HIV in the setting of CAB-LA PrEP. IMPORTANCE: HIV RNA assays can detect HIV infections earlier than HIV rapid tests or Ag/Ab tests in persons using CAB-LA PrEP. Earlier HIV diagnosis could allow for earlier treatment initiation and reduced risk of INSTI resistance. POC tests may help detect HIV infection before CAB-LA administration and may be more accessible than laboratory-based assays in some settings. In this study, the POC Xpert VL-XC assay detected HIV RNA in most samples from individuals who received CAB-LA PrEP and had delayed detection of HIV infection with HIV rapid tests and an Ag/Ab test. The performance of this assay was similar to laboratory-based HIV RNA assays in this cohort. The POC Xpert Qual-XC assay detects both HIV RNA and DNA, with a higher viral load cutoff for RNA detection. This assay was negative for most lower viral load samples and did not offer an advantage for HIV screening in persons using CAB-LA PrEP.

Extended Analysis of HIV Infection in Cisgender Men and Transgender Women Who Have Sex with Men Receiving Injectable Cabotegravir for HIV Prevention: HPTN 083.

HPTN 083 demonstrated that injectable cabotegravir (CAB) was superior to oral tenofovir disoproxil fumarate-emtricitabine (TDF-FTC) for HIV prevention in cisgender men and transgender women who have sex with men. We previously analyzed 58 infections in the blinded phase of HPTN 083 (16 in the CAB arm and 42 in the TDF-FTC arm). This report describes 52 additional infections that occurred up to 1 year after study unblinding (18 in the CAB arm and 34 in the TDF-FTC arm). Retrospective testing included HIV testing, viral load testing, quantification of study drug concentrations, and drug resistance testing. The new CAB arm infections included 7 with CAB administration within 6 months of the first HIV-positive visit (2 with on-time injections, 3 with ≥1 delayed injection, and 2 who restarted CAB) and 11 with no recent CAB administration. Three cases had integrase strand transfer inhibitor (INSTI) resistance (2 with on-time injections and 1 who restarted CAB). Among 34 CAB infections analyzed to date, diagnosis delays and INSTI resistance were significantly more common in infections with CAB administration within 6 months of the first HIV-positive visit. This report further characterizes HIV infections in persons receiving CAB preexposure prophylaxis and helps define the impact of CAB on the detection of infection and the emergence of INSTI resistance.

Assessing reproductive toxicity of two environmental toxicants with a novel in vitro human spermatogenic model.

Environmental influences and insults by reproductive toxicant exposure can lead to impaired spermatogenesis or infertility. Understanding how toxicants disrupt spermatogenesis is critical for determining how environmental factors contribute to impaired fertility. While current animal models are available, understanding of the reproductive toxic effects on human fertility requires a more robust model system. We recently demonstrated that human pluripotent stem cells can differentiate into spermatogonial stem cells/spermatogonia, primary and secondary spermatocytes, and haploid spermatids; a model that mimics many aspects of human spermatogenesis. Here, using this model system, we examine the effects of 2-bromopropane (2-BP) and 1,2,dibromo-3-chloropropane (DBCP) on in vitro human spermatogenesis. 2-BP and DBCP are non-endocrine disrupting toxicants that are known to impact male fertility. We show that acute treatment with either 2-BP or DBCP induces a reduction in germ cell viability through apoptosis. 2-BP and DBCP affect viability of different cell populations as 2-BP primarily reduces spermatocyte viability, whereas DBCP exerts a much greater effect on spermatogonia. Acute treatment with 2-BP or DBCP also reduces the percentage of haploid spermatids. Both 2-BP and DBCP induce reactive oxygen species (ROS) formation leading to an oxidized cellular environment. Taken together, these results suggest that acute exposure with 2-BP or DBCP causes human germ cell death in vitro by inducing ROS formation. This system represents a unique platform for assessing human reproductive toxicity potential of various environmental toxicants in a rapid, efficient, and unbiased format.