Vertical transmission of HIV among pregnant women who initially had false–negative rapid HIV tests in four South African antenatal clinics

INTRODUCTION : There is a risk of mother-to-child transmission of HIV (MTCT) during pregnancy and breastfeeding. The aim of this study was to assess vertical transmission of HIV among pregnant women who initially had false–negative rapid HIV tests in South African antenatal care (ANC) clinics. METHODS : Pregnant participants were enrolled in a diagnostic study that used nucleic acid amplification testing (NAAT) to screen for early HIV infection among individuals who tested negative on rapid HIV tests used at the point-of-care (POC) facilities. Participants were enrolled from four ANC clinics in the Tshwane district of South Africa. All NAAT-positive participants were recalled to the clinics for further management. Vertical transmission was assessed among exposed infants whose HIV polymerase chain reaction (PCR) results were available. RESULTS : This study enrolled 8208 pregnant participants who tested negative on rapid HIV tests between 2013 and 2016. Their median age was 26 years (interquartile range [IQR]: 23–30). NAAT detected HIV infections in 0.6% (n = 49; 95% confidence interval {CI}: 0.5–0.8) of all study participants. The distribution of these infections among the four clinics ranged from 0.3%– 1.1%, but this was not statistically significant (p = 0.07). Forty-seven participants (95.9%) were successfully recalled and referred for antiretroviral treatment initiation as part of prevention of MTCT (PMTCT). Most women with newly diagnosed HIV infection presented for the first ANC visit in the second (61.9%, n = 26) and third (31.0%, n = 13) trimesters. HIV PCR results were available for thirty-two infants, three of whom tested positive (9.4%; 95% CI: 1.98–25.02). CONCLUSIONS : This study showed that supplemental HIV testing for pregnant women led to earlier linkage to the PMTCT programme. Inaccurate diagnosis of HIV infection at ANC clinics is likely to undermine the efforts of eliminating MTCT particularly in HIV-endemic settings.S1 Table. Characteristics of participants diagnosed with early or chronic HIV infection. Initial tests were performed from samples obtained at enrolment (i.e. after a negative rapid HIV test result). HIV viral load (VL) tests were performed first to screen for HIV infection, and all the serology tests were performed later. Follow-up (F/U) VL was only performed for participants who had an initial VL <5000 copies/ml [16]. Pt ID = participant’s study identity, F = female, gen = generation, ELISA = enzyme-linked immunosorbent assay, W. Blot = Western Blot, LAg = limiting antigen, Insuf = insufficient, LT = long term (chronic) infection, --- = not available (participant did not return for follow-up), + = positive,— = negative. Units: HIV VL = copies/ml; p24 antigen = cut-off index (COI); Genscreen ELISA = sample cut-off (S/CO); LAg avidity = normalized optical density (OD-n); LAg avidity <1.5 OD-n = early infection; LAg avidity >1.5 OD-n = LT (chronic) infection. ¥ = participant 6738 was previously misclassified as having chronic infection [16], but testing on her follow-up sample revealed low avidity antibodies consistent with early infection; this was confirmed on repeat testing of 6738 sample. P24 antigen, W. Blot and F/U LAg were not performed for the last participants identified with newly diagnosed HIV infection owing to cost limitations. This also applies to the F/U VL for participant 1692, as this was supposed to have been performed according to the diagnostic study protocol [14].This work was supported by SHM - South African Medical Research Council – Self Initiated Research (SA MRC-SIR) grant; SHM - Discovery Foundation grant; SHM - Hamilton Naki Clinical Scholarship; and TCQ - The Division of Intramural Research, NIAID, NIH.SHM - South African Medical Research Council – Self Initiated Research (SA MRC-SIR) grant; SHM - Discovery Foundation grant; SHM - Hamilton Naki Clinical Scholarship; and TCQ - The Division of Intramural Research, NIAID, NIH.http://www.plosone.orgam2020Internal Medicin

Vertical transmission of HIV among pregnant women who initially had false–negative rapid HIV tests in four South African antenatal clinics

INTRODUCTION : There is a risk of mother-to-child transmission of HIV (MTCT) during pregnancy and breastfeeding. The aim of this study was to assess vertical transmission of HIV among pregnant women who initially had false–negative rapid HIV tests in South African antenatal care (ANC) clinics. METHODS : Pregnant participants were enrolled in a diagnostic study that used nucleic acid amplification testing (NAAT) to screen for early HIV infection among individuals who tested negative on rapid HIV tests used at the point-of-care (POC) facilities. Participants were enrolled from four ANC clinics in the Tshwane district of South Africa. All NAAT-positive participants were recalled to the clinics for further management. Vertical transmission was assessed among exposed infants whose HIV polymerase chain reaction (PCR) results were available. RESULTS : This study enrolled 8208 pregnant participants who tested negative on rapid HIV tests between 2013 and 2016. Their median age was 26 years (interquartile range [IQR]: 23–30). NAAT detected HIV infections in 0.6% (n = 49; 95% confidence interval {CI}: 0.5–0.8) of all study participants. The distribution of these infections among the four clinics ranged from 0.3%– 1.1%, but this was not statistically significant (p = 0.07). Forty-seven participants (95.9%) were successfully recalled and referred for antiretroviral treatment initiation as part of prevention of MTCT (PMTCT). Most women with newly diagnosed HIV infection presented for the first ANC visit in the second (61.9%, n = 26) and third (31.0%, n = 13) trimesters. HIV PCR results were available for thirty-two infants, three of whom tested positive (9.4%; 95% CI: 1.98–25.02). CONCLUSIONS : This study showed that supplemental HIV testing for pregnant women led to earlier linkage to the PMTCT programme. Inaccurate diagnosis of HIV infection at ANC clinics is likely to undermine the efforts of eliminating MTCT particularly in HIV-endemic settings.S1 Table. Characteristics of participants diagnosed with early or chronic HIV infection. Initial tests were performed from samples obtained at enrolment (i.e. after a negative rapid HIV test result). HIV viral load (VL) tests were performed first to screen for HIV infection, and all the serology tests were performed later. Follow-up (F/U) VL was only performed for participants who had an initial VL <5000 copies/ml [16]. Pt ID = participant’s study identity, F = female, gen = generation, ELISA = enzyme-linked immunosorbent assay, W. Blot = Western Blot, LAg = limiting antigen, Insuf = insufficient, LT = long term (chronic) infection, --- = not available (participant did not return for follow-up), + = positive,— = negative. Units: HIV VL = copies/ml; p24 antigen = cut-off index (COI); Genscreen ELISA = sample cut-off (S/CO); LAg avidity = normalized optical density (OD-n); LAg avidity <1.5 OD-n = early infection; LAg avidity >1.5 OD-n = LT (chronic) infection. ¥ = participant 6738 was previously misclassified as having chronic infection [16], but testing on her follow-up sample revealed low avidity antibodies consistent with early infection; this was confirmed on repeat testing of 6738 sample. P24 antigen, W. Blot and F/U LAg were not performed for the last participants identified with newly diagnosed HIV infection owing to cost limitations. This also applies to the F/U VL for participant 1692, as this was supposed to have been performed according to the diagnostic study protocol [14].This work was supported by SHM - South African Medical Research Council – Self Initiated Research (SA MRC-SIR) grant; SHM - Discovery Foundation grant; SHM - Hamilton Naki Clinical Scholarship; and TCQ - The Division of Intramural Research, NIAID, NIH.SHM - South African Medical Research Council – Self Initiated Research (SA MRC-SIR) grant; SHM - Discovery Foundation grant; SHM - Hamilton Naki Clinical Scholarship; and TCQ - The Division of Intramural Research, NIAID, NIH.http://www.plosone.orgam2020Internal Medicin

Impact of optimized PET imaging conditions on F-18-FDG uptake quantification in patients with apparently normal aortas

Background The cardiovascular committee of the European Association of Nuclear Medicine (EANM) recently published recommendations on imaging conditions to be observed during F-18-FDG PET imaging of vascular inflammation. This study aimed to evaluate the impact of applying these optimized imaging conditions on PET quantification of arterial F-18-FDG uptake. Methods and Results Fifty-seven patients were prospectively recruited to undergo an early F-18-FDG PET/CT imaging at 60 minutes and repeat delayed imaging at >= 120 minutes post tracer injection. Routine oncologic F-18-FDG PET protocol was observed for early imaging, while delayed imaging parameters were optimized for vascular inflammation imaging as recommended by the EANM. Aortic SUVmax of the ascending aorta and SUVmean from the lumen of the superior vena cava (SVC SUVmean) were obtained on early and delayed imaging. Target-to-background ratio (TBR) was obtained for the early and delayed imaging. Aortic SUVmax increased by a mean of 70%, while SVC SUVmean decreased by a mean of 52% between early and delayed imaging (P 180 minutes. Aortic SUVmax significantly increased at imaging time-points between 120 and 180 minutes. No significant improvement in aortic SUVmax was seen at imaging time-points beyond 180 minutes. Conclusions F-18-FDG PET imaging conditions optimized for vascular inflammation imaging lead to an improved quantification through an increase in the quantified vascular tracer uptake and decrease in blood-pool background activity

Detection of acute and early HIV-1 infections in an HIV hyper-endemic area with limited resources

BACKGROUND: Two thirds of the world's new HIV infections are in sub-Saharan Africa. Acute HIV infection (AHI) is the time of virus acquisition until the appearance of HIV antibodies. Early HIV infection, which includes AHI, is the interval between virus acquisition and establishment of viral load set-point. This study aimed to detect acute and early HIV infections in a hyper-endemic setting. METHODS: This was a cross-sectional diagnostic study that enrolled individuals who had negative rapid HIV results in five clinics in South Africa. Pooled nucleic acid amplification testing (NAAT) was performed, followed by individual sample testing in positive pools. NAAT-positive participants were recalled to the clinics for confirmatory testing and appropriate management. HIV antibody, p24 antigen, Western Blot and avidity tests were performed for characterization of NAAT-positive samples. RESULTS: The study enrolled 6910 individuals with negative rapid HIV results. Median age was 27 years (interquartile range {IQR}: 23-31). NAAT was positive in 55 samples, resulting in 0.8% newly diagnosed HIV-infected individuals (95% confidence interval {CI}: 0.6-1.0). The negative predictive value for rapid HIV testing was 99.2% (95% CI: 99.0-99.4). Characterization of NAAT-positive samples revealed that 0.04% (95% CI: 0.000-0.001) had AHI, 0.3% (95% CI: 0.1-0.4) had early HIV infection, and 0.5% (95% CI: 0.5-0.7) had chronic HIV infection. Forty-seven (86%) of NAAT-positive participants returned for follow-up at a median of 4 weeks (IQR: 2-8). Follow-up rapid tests were positive in 96% of these participants. CONCLUSIONS: NAAT demonstrated that a substantial number of HIV-infected individuals are misdiagnosed at South African points-of-care. Follow-up rapid tests done within a 4 week interval detected early and chronic HIV infections initially missed by rapid HIV testing. This may be a practical and affordable strategy for earlier detection of these infections in resource-constrained settings. Newer molecular tests that can be used at the points-of-care should be evaluated for routine diagnosis of HIV in hyper-endemic settings.National Health Laboratory Service Research Trust (NHLS-RT) grant (www.nhls.ac. za), SHM and DJM. Federation of Infectious Diseases Societies of Southern Africa and GlaxoSmithKline (FIDSSA- GSK) grant (www.fidssa.co.za), University of Pretoria research assistant grant (www.up.ac.za) and research grant from GlaxoSmithKline, SHM. South African Medical Research Council Self Initiated Research (MRC-SIR) grant (www.mrc.ac.za), Discovery Foundation (www.tshikululu.org.za), SHM. Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health (www.nih.gov), TCQ and OL; Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health.http://www.plosone.orgam2016Internal MedicineMedical Microbiolog

Potassium tert-Butoxide-Catalyzed Dehydrogenative C–H Silylation of Heteroaromatics: A Combined Experimental and Computational Mechanistic Study

We recently reported a new method for the direct dehydrogenative C–H silylation of heteroaromatics utilizing Earth-abundant potassium tert-butoxide. Herein we report a systematic experimental and computational mechanistic investigation of this transformation. Our experimental results are consistent with a radical chain mechanism. A trialkylsilyl radical may be initially generated by homolytic cleavage of a weakened Si–H bond of a hypercoordinated silicon species as detected by IR, or by traces of oxygen which can generate a reactive peroxide by reaction with (KOt-Bu)_4 as indicated by density functional theory (DFT) calculations. Radical clock and kinetic isotope experiments support a mechanism in which the C–Si bond is formed through silyl radical addition to the heterocycle followed by subsequent β-hydrogen scission. DFT calculations reveal a reasonable energy profile for a radical mechanism and support the experimentally observed regioselectivity. The silylation reaction is shown to be reversible, with an equilibrium favoring products due to the generation of H_2 gas. In situ NMR experiments with deuterated substrates show that H_2 is formed by a cross-dehydrogenative mechanism. The stereochemical course at the silicon center was investigated utilizing a ^2H-labeled silolane probe; complete scrambling at the silicon center was observed, consistent with a number of possible radical intermediates or hypercoordinate silicates

Vertical transmission of HIV among pregnant women who initially had false-negative rapid HIV tests in four South African antenatal clinics.

IntroductionThere is a risk of mother-to-child transmission of HIV (MTCT) during pregnancy and breastfeeding. The aim of this study was to assess vertical transmission of HIV among pregnant women who initially had false-negative rapid HIV tests in South African antenatal care (ANC) clinics.MethodsPregnant participants were enrolled in a diagnostic study that used nucleic acid amplification testing (NAAT) to screen for early HIV infection among individuals who tested negative on rapid HIV tests used at the point-of-care (POC) facilities. Participants were enrolled from four ANC clinics in the Tshwane district of South Africa. All NAAT-positive participants were recalled to the clinics for further management. Vertical transmission was assessed among exposed infants whose HIV polymerase chain reaction (PCR) results were available.ResultsThis study enrolled 8208 pregnant participants who tested negative on rapid HIV tests between 2013 and 2016. Their median age was 26 years (interquartile range [IQR]: 23-30). NAAT detected HIV infections in 0.6% (n = 49; 95% confidence interval {CI}: 0.5-0.8) of all study participants. The distribution of these infections among the four clinics ranged from 0.3%- 1.1%, but this was not statistically significant (p = 0.07). Forty-seven participants (95.9%) were successfully recalled and referred for antiretroviral treatment initiation as part of prevention of MTCT (PMTCT). Most women with newly diagnosed HIV infection presented for the first ANC visit in the second (61.9%, n = 26) and third (31.0%, n = 13) trimesters. HIV PCR results were available for thirty-two infants, three of whom tested positive (9.4%; 95% CI: 1.98-25.02).ConclusionsThis study showed that supplemental HIV testing for pregnant women led to earlier linkage to the PMTCT programme. Inaccurate diagnosis of HIV infection at ANC clinics is likely to undermine the efforts of eliminating MTCT particularly in HIV-endemic settings

Field performance of the INSTI HIV‐1/‐2 antibody test in two South African antenatal clinics

This was a prospective study that assessed field performance of the INSTI HIV‐1/‐2 antibody test (INSTI test) in two antenatal clinics in South Africa (SA). INSTI test was evaluated against rapid tests used at these clinics, and pooled nucleic acid amplification testing (NAAT) performed for individuals with negative rapid tests. Three hundred and eighty‐six pregnant women were enrolled; 334 (86.5%) with negative results on the screening rapid test, and 52 (13.5%; 95% confidence interval [CI]: 10.2–17.3%) with positive results on screening and confirmatory rapid tests. INSTI test yielded the same results as other rapid tests in all participants, thus showing a 100% sensitivity (95% CI: 93.2–100.0%) and specificity (95% CI: 98.9–100.0%). Pooled NAAT was performed for 290 participants who had negative rapid tests, and yielded negative results in all pools. These data show excellent field performance of the INSTI test, and highlight that this test can be implementedat SA clinics.The South African Medical Research Council—Self Initiated Research (SA MRC—SIR) grant, Discovery Foundation grant, Hamilton Naki Clinical Scholarship, and The Division of Intramural Research, NIAID, NIH.http://wileyonlinelibrary.com/journal/jmv2020-07-01hj2019Internal MedicineMedical Virolog

High risk exposure to HIV among sexually active individuals who tested negative on rapid HIV Tests in the Tshwane District of South Africa - the importance of behavioural prevention measures

CITATION: Mayaphi, S. H. et al. 2018. High risk exposure to HIV among sexually active individuals who tested negative on rapid HIV Tests in the Tshwane District of South Africa - the importance of behavioural prevention measures. PLoS ONE, 13(2):e0192357, doi:10.1371/journal.pone.0192357.The original publication is available at https://journals.plos.org/plosoneObjective: To assess the prevalence of HIV risk behaviour among sexually active HIV sero-negative individuals in the Tshwane district of South Africa (SA). Methods: Demographic and HIV risk behaviour data were collected on a questionnaire from participants of a cross-sectional study that screened for early HIV infection using pooled nucleic acid amplification testing (NAAT). The study enrolled individuals who tested negative on rapid HIV tests performed at five HIV counseling and testing (HCT) clinics, which included four antenatal clinics and one general HCT clinic. Results: The study enrolled 9547 predominantly black participants (96.6%) with a median age of 27 years (interquartile range [IQR]: 23–31). There were 1661 non-pregnant and 7886 pregnant participants largely enrolled from the general and antenatal HCT clinics, respectively. NAAT detected HIV infection in 61 participants (0.6%; 95% confidence interval [CI]: 0.4–0.8) in the whole study. A high proportion of study participants, 62.8% and 63.0%, were unaware of their partner’s HIV status; and also had high prevalence, 88.5% and 99.5%, of recent unprotected sex in the general and pregnant population, respectively. Consistent use of condoms was associated with protection against HIV infection in the general population. Trends of higher odds for HIV infection were observed with most demographic and HIV risk factors at univariate analysis, however, multivariate analysis did not show statistical significance for almost all these factors. A significantly lower risk of HIV infection was observed in circumcised men (p <0.001). Conclusions: These data show that a large segment of sexually active people in the Tshwane district of SA have high risk exposure to HIV. The detection of newly diagnosed HIV infections in all study clinics reflects a wide distribution of individuals who are capable of sustaining HIV transmission in the setting where HIV risk behaviour is highly prevalent. A questionnaire that captures HIV risk behaviour would be useful during HIV counselling and testing to ensure that there is a systematic way of identifying HIV risk factors and that counselling is optimised for each individual. HIV risk behaviour surveillance could be used to inform relevant HIV prevention interventions that could be implemented at a community or population level.https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0192357Publisher's versio

Detection of Acute and Early HIV-1 Infections in an HIV Hyper-Endemic Area with Limited Resources.

Two thirds of the world's new HIV infections are in sub-Saharan Africa. Acute HIV infection (AHI) is the time of virus acquisition until the appearance of HIV antibodies. Early HIV infection, which includes AHI, is the interval between virus acquisition and establishment of viral load set-point. This study aimed to detect acute and early HIV infections in a hyper-endemic setting.This was a cross-sectional diagnostic study that enrolled individuals who had negative rapid HIV results in five clinics in South Africa. Pooled nucleic acid amplification testing (NAAT) was performed, followed by individual sample testing in positive pools. NAAT-positive participants were recalled to the clinics for confirmatory testing and appropriate management. HIV antibody, p24 antigen, Western Blot and avidity tests were performed for characterization of NAAT-positive samples.The study enrolled 6910 individuals with negative rapid HIV results. Median age was 27 years (interquartile range {IQR}: 23-31). NAAT was positive in 55 samples, resulting in 0.8% newly diagnosed HIV-infected individuals (95% confidence interval {CI}: 0.6-1.0). The negative predictive value for rapid HIV testing was 99.2% (95% CI: 99.0-99.4). Characterization of NAAT-positive samples revealed that 0.04% (95% CI: 0.000-0.001) had AHI, 0.3% (95% CI: 0.1-0.4) had early HIV infection, and 0.5% (95% CI: 0.5-0.7) had chronic HIV infection. Forty-seven (86%) of NAAT-positive participants returned for follow-up at a median of 4 weeks (IQR: 2-8). Follow-up rapid tests were positive in 96% of these participants.NAAT demonstrated that a substantial number of HIV-infected individuals are misdiagnosed at South African points-of-care. Follow-up rapid tests done within a 4 week interval detected early and chronic HIV infections initially missed by rapid HIV testing. This may be a practical and affordable strategy for earlier detection of these infections in resource-constrained settings. Newer molecular tests that can be used at the points-of-care should be evaluated for routine diagnosis of HIV in hyper-endemic settings