Differences in neutralizing antibody sensitivities and envelope characteristics indicate distinct antigenic properties of Nigerian HIV-1 subtype G and CRF02_AG.

The magnitude of the HIV-1 epidemic in Nigeria is second only to the subtype C epidemic in South Africa, yet the subtypes prevalent in Nigeria require further characterization. A panel of 50 subtype G and 18 CRF02_AG Nigerian HIV-1 pseudoviruses (PSV) was developed and envelope coreceptor usage, neutralization sensitivity and cross-clade reactivity were characterized. These PSV were neutralized by some antibodies targeting major neutralizing determinants, but potentially important differences were observed in specific sensitivities (eg. to sCD4, MPER and V2/V3 monoclonal antibodies), as well as in properties such as variable loop lengths, number of potential N-linked glycans and charge, demonstrating distinct antigenic characteristics of CRF02_AG and subtype G. There was preferential neutralization of the matched CRF/subtype when PSV from subtype G or CRF02_AG were tested using pooled plasma. These novel Nigerian PSV will be useful to study HIV-1 CRF- or subtype-specific humoral immune responses for subtype G and CRF02_AG.

Progress towards the UNAIDS 95-95-95 targets in the Fifth Botswana AIDS Impact Survey (BAIS V 2021): a nationally representative survey.

BACKGROUND: In 2014, UNAIDS set a goal to end the AIDS epidemic by achieving targets for the percentage of people living with HIV who were aware of their status, on antiretroviral therapy (ART), and virally suppressed. In 2020, these targets were revised to 95% for each measure (known as 95-95-95), to be reached among people living with HIV by 2025. We used data from the Fifth Botswana AIDS Impact Survey (BAIS V) to measure progress towards these testing and treatment targets in Botswana. METHODS: BAIS V used a two-stage cluster design to obtain a nationally representative sample of people aged 15-64 years in Botswana. During March-August, 2021, 14 763 consenting participants were interviewed and tested for HIV in their households by survey teams. HIV-positive specimens were tested for viral load, presence of antiretroviral drugs, and recency of infection using the HIV-1 limiting antigen avidity enzyme immunoassay. Estimates of HIV-positive status and use of ART were based on self-report and the analysis of blood specimens for antiretroviral drugs. Viral load suppression was defined as an HIV RNA concentration of less than 1000 copies per mL. HIV incidence was calculated using the recent infection testing algorithm. Data were weighted to account for the complex survey design. FINDINGS: The national HIV prevalence in Botswana among people aged 15-64 years was 20·8% and the annual incidence of HIV infection was 0·2%. 95·1% (men 93·0%, women 96·4%) of people living with HIV aged 15-64 years were aware of their status, 98·0% (men 97·2%, women 98·4%) of those aware were on ART, and 97·9% (men 96·6%, women 98·6%) of those on ART had viral load suppression. Among young people (aged 15-24 years) living with HIV, 84·5% were aware of their status, 98·5% of those aware were on ART, and 91·6% of those on ART had viral load suppression. The prevalance of viral load suppression among all people living with HIV was 91·8%, and varied by district-ranging from 85·3% in Gaborone to 100·0% in Selibe Phikwe. INTERPRETATION: BAIS V is the first population-based survey worldwide to report the achievement of the UNAIDS 95-95-95 goals, both overall and among women. Strategies to reach undiagnosed men and young people, including young women, are needed. FUNDING: US President's Emergency Plan for AIDS Relief.

Longitudinal gut microbiota composition of South African and Nigerian infants in relation to tetanus vaccine responses.

Infants who are exposed to HIV but uninfected (iHEU) have higher risk of infectious morbidity than infants who are HIV-unexposed and uninfected (iHUU), possibly due to altered immunity. As infant gut microbiota may influence immune development, we evaluated the effects of HIV exposure on infant gut microbiota and its association with tetanus toxoid vaccine responses. We evaluated the gut microbiota of 82 South African (61 iHEU and 21 iHUU) and 196 Nigerian (141 iHEU and 55 iHUU) infants at <1 and 15 weeks of life by 16S rRNA gene sequencing. Anti-tetanus antibodies were measured by enzyme-linked immunosorbent assay at matched time points. Gut microbiota in the 278 included infants and its succession were more strongly influenced by geographical location and age than by HIV exposure. Microbiota of Nigerian infants, who were exclusively breastfed, drastically changed over 15 weeks, becoming dominated by Bifidobacterium longum subspecies infantis. This change was not observed among South African infants, even when limiting the analysis to exclusively breastfed infants. The Least Absolute Shrinkage and Selection Operator regression suggested that HIV exposure and gut microbiota were independently associated with tetanus titers at week 15, and that high passively transferred antibody levels, as seen in the Nigerian cohort, may mitigate these effects. In conclusion, in two African cohorts, HIV exposure minimally altered the infant gut microbiota compared to age and setting, but both specific gut microbes and HIV exposure independently predicted humoral tetanus vaccine responses.IMPORTANCEGut microbiota plays an essential role in immune system development. Since infants HIV-exposed and uninfected (iHEU) are more vulnerable to infectious diseases than unexposed infants, we explored the impact of HIV exposure on gut microbiota and its association with vaccine responses. This study was conducted in two African countries with rapidly increasing numbers of iHEU. Infant HIV exposure did not substantially affect gut microbial succession, but geographic location had a strong effect. However, both the relative abundance of specific gut microbes and HIV exposure were independently associated with tetanus titers, which were also influenced by baseline tetanus titers (maternal transfer). Our findings provide insight into the effect of HIV exposure, passive maternal antibody, and gut microbiota on infant humoral vaccine responses.

Comparison of HIV prevalence, incidence, and viral load suppression in Zambia population-based HIV impact assessments from 2016 and 2021.

BACKGROUND: The Zambian government has implemented a public health response to control the HIV epidemic in the country. Zambia conducted a population-based HIV impact assessment (ZAMPHIA) survey in 2021 to assess the status of the HIV epidemic to guide its public health programs. METHODS: ZAMPHIA 2021 was a cross-sectional two-stage cluster sample household survey among persons aged ≥15 years conducted in Zambia across all 10 provinces. Consenting participants were administered a standardized questionnaire and whole blood was tested for HIV according to national guidelines. HIV-1 viral load (VL), recent HIV infection, and antiretroviral medications were tested for in HIV-seropositive samples. Viral load suppression (VLS) was defined as <1000 copies/ml. ZAMPHIA 2021 results were compared to ZAMPHIA 2016 for persons aged 15-59 years (i.e., the overlapping age ranges). All estimates were weighted to account for nonresponse and survey design. RESULTS: During ZAMPHIA 2021, of 25 483 eligible persons aged ≥15 years, 18 804 (73.8%) were interviewed and tested for HIV. HIV prevalence was 11.0% and VLS prevalence was 86.2% overall, but was <80% among people living with HIV aged 15-24 years and in certain provinces. Among persons aged 15-59 years, from 2016 to 2021, HIV incidence declined from 0.6% to 0.3% ( P -value: 0.07) and VLS prevalence increased from 59.2% to 85.7% ( P -value: <0.01). DISCUSSION: Zambia has made substantial progress toward controlling the HIV epidemic from 2016 to 2021. Continued implementation of a test-and-treat strategy, with attention to groups with lower VLS in the ZAMPHIA 2021, could support reductions in HIV incidence and improve overall VLS in Zambia.

Corrigendum: Assuring the quality of diagnostic testing: the future is now.

[This corrects the article DOI: 10.4102/ajlm.v5i2.558.].