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  • Springer Science and Business Media LLC  (8)
  • Bekker, Linda-Gail  (8)
  • 1
    Online Resource
    Online Resource
    Quantifying how single dose Ad26.COV2.S vaccine efficacy depends on Spike sequence features
    Springer Science and Business Media LLC ; 2024
    In:  Nature Communications Vol. 15, No. 1 ( 2024-03-11)
    Details
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 15, No. 1 ( 2024-03-11)
    Abstract: In the ENSEMBLE randomized, placebo-controlled phase 3 trial (NCT04505722), estimated single-dose Ad26.COV2.S vaccine efficacy (VE) was 56% against moderate to severe–critical COVID-19. SARS-CoV-2 Spike sequences were determined from 484 vaccine and 1,067 placebo recipients who acquired COVID-19. In this set of prespecified analyses, we show that in Latin America, VE was significantly lower against Lambda vs. Reference and against Lambda vs. non-Lambda [family-wise error rate (FWER) p 〈 0.05]. VE differed by residue match vs. mismatch to the vaccine-insert at 16 amino acid positions (4 FWER p 〈 0.05; 12 q-value ≤ 0.20); significantly decreased with physicochemical-weighted Hamming distance to the vaccine-strain sequence for Spike, receptor-binding domain, N-terminal domain, and S1 (FWER p 〈 0.001); differed (FWER ≤ 0.05) by distance to the vaccine strain measured by 9 antibody-epitope escape scores and 4 NTD neutralization-impacting features; and decreased (p = 0.011) with neutralization resistance level to vaccinee sera. VE against severe–critical COVID-19 was stable across most sequence features but lower against the most distant viruses.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    URL: Article
    DOI: 10.1038/s41467-024-46536-w
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2024
    detail.hit.zdb_id: 2553671-0
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  • 2
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    Review of preventative HIV vaccine clinical trials in South Africa
    Springer Science and Business Media LLC ; 2020
    In:  Archives of Virology Vol. 165, No. 11 ( 2020-11), p. 2439-2452
    Details
    In: Archives of Virology, Springer Science and Business Media LLC, Vol. 165, No. 11 ( 2020-11), p. 2439-2452
    Abstract: New HIV infections continue relentlessly in southern Africa, demonstrating the need for a vaccine to prevent HIV subtype C. In South Africa, the country with the highest number of new infections annually, HIV vaccine research has been ongoing since 2003 with collaborative public-private-philanthropic partnerships. So far, 21 clinical trials have been conducted in South Africa, investigating seven viral vectors, three DNA plasmids, four envelope proteins, five adjuvants and three monoclonal antibodies. Active vaccine candidates have spanned subtypes A, B, C, E and multi-subtype mosaic sequences. All were well tolerated. Four concepts were investigated for efficacy: rAd5-gag/pol/nef showed increased HIV acquisition in males, subtype C ALVAC/gp120/MF59 showed no preventative efficacy, and the trials for the VRC01 monoclonal antibody and Ad26.Mos4.HIV/subtype C gp140/ aluminum phosphate are ongoing. Future trials are planned with DNA/viral vector plus protein combinations in concert with pre-exposure prophylaxis, and sequential immunization studies with transmitted/founder HIV envelope to induce broadly neutralizing antibodies. Finally, passive immunization trials are underway to build on the experience with VRC01, including single and combination antibody trials with an antibody derived from a subtype-C-infected South African donor. Future consideration should be given to the evaluation of novel strategies, for example, inactivated-whole-virus vaccines.
    Type of Medium: Online Resource
    ISSN: 0304-8608 , 1432-8798
    URL: Article
    DOI: 10.1007/s00705-020-04777-2
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 1458460-8
    SSG: 12
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  • 3
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    Meeting report: South African Medical Research Council Standard of Care in Clinical Research in Low- And Middle-Income Settings Summit, November 2017
    Springer Science and Business Media LLC ; 2021
    In:  Trials Vol. 22, No. 1 ( 2021-12)
    Details
    In: Trials, Springer Science and Business Media LLC, Vol. 22, No. 1 ( 2021-12)
    Abstract: A cornerstone of HIV prevention clinical trials is providing a combination prevention package to all trial participants. The elements included in that standard of care (SoC) package evolve as new prevention modalities are developed. Pre-exposure prophylaxis (PrEP) was recommended by the World Health Organization for persons at high risk of acquiring HIV, but not all countries immediately adopted those recommendations. The South African Medical Research Council (SAMRC) convened a summit to discuss issues relating to SoC and PrEP in HIV prevention clinical trials taking place in lower- to middle-income countries (LMIC). Policymakers, regulators, ethicists, experts in law, researchers, representatives of advocacy groups, and the HIV Vaccine Trials Network (HVTN) presented a framework within which SoC principles could be articulated. A group of subject matter experts presented on the regulatory, ethical, scientific, and historic framework of SoC in clinical trials, focusing on PrEP in South Africa. Summit participants discussed how and when to include new HIV treatment and prevention practices into existing clinical guidelines and trial protocols, as well as the opportunities for and challenges to scaling up interventions. The summit addressed challenges to PrEP provision, such as inconsistent efficacy amongst different populations and various biological, virological, and immunological explanations for this heterogeneity. Advocates and community members propagated the urgent need for accessible interventions that could avert HIV infection. The meeting recommended supporting access to PrEP in HIV prevention trials by (1) developing PrEP access plans for HIV vaccine trials, (2) creating a PrEP fund that would supply PrEP to sites conducting HIV prevention trials via a central procurement mechanism, and (3) supporting the safety monitoring of PrEP. This report summarizes the presentations and discussions from the summit in order to highlight the importance of SoC in HIV prevention clinical trials.
    Type of Medium: Online Resource
    ISSN: 1745-6215
    URL: Article
    DOI: 10.1186/s13063-021-05754-z
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2040523-6
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  • 4
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    HIV-1 Vaccine Sequences Impact V1V2 Antibody Responses: A Comparison of Two Poxvirus Prime gp120 Boost Vaccine Regimens
    Springer Science and Business Media LLC ; 2020
    In:  Scientific Reports Vol. 10, No. 1 ( 2020-02-07)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 10, No. 1 ( 2020-02-07)
    Abstract: In the RV144 trial, vaccine-induced V1V2 IgG correlated with decreased HIV-1 risk. We investigated circulating antibody specificities in two phase 1 poxvirus prime-protein boost clinical trials conducted in South Africa: HVTN 097 (subtype B/E) and HVTN 100 (subtype C). With cross-subtype peptide microarrays and multiplex binding assays, we probed the magnitude and breadth of circulating antibody responses to linear variable loop 2 (V2) and conformational V1V2 specificities. Antibodies targeting the linear V2 epitope, a correlate of decreased HIV-1 risk in RV144, were elicited up to 100% and 61% in HVTN 097 and HVTN 100, respectively. Despite higher magnitude of envelope-specific responses in HVTN 100 compared to HVTN 097 (p’s  〈  0.001), the magnitude and positivity for V2 linear epitope and V1V2 proteins were significantly lower in HVTN 100 compared to HVTN 097. Meanwhile, responses to other major linear epitopes including the variable 3 (V3) and constant 5 (C5) epitopes were higher in HVTN 100 compared to HVTN 097. Our data reveal substantial differences in the circulating antibody specificities induced by vaccination in these two canarypox prime-protein boost trials. Our findings suggest that the choice of viral sequences in prime-boost vaccine regimens, and potentially adjuvants and immunogen dose, influence the elicitation of V2-specific antibodies.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-020-57491-z
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2615211-3
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  • 5
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    Risk Factors Associated with HIV Acquisition in Males Participating in HIV Vaccine Efficacy Trials in South Africa
    Springer Science and Business Media LLC ; 2023
    In:  AIDS and Behavior Vol. 27, No. 9 ( 2023-09), p. 3027-3037
    Details
    In: AIDS and Behavior, Springer Science and Business Media LLC, Vol. 27, No. 9 ( 2023-09), p. 3027-3037
    Abstract: In South Africa, HIV acquisition risk has been studied less in people assigned male at birth. We studied the associations between risk behaviors, clinical features and HIV incidence amongst males in two South African HIV preventive vaccine efficacy trials. We used Cox proportional hazards models to test for associations between demographics, sexual behaviors, clinical variables and HIV acquisition among males followed in the HVTN 503 (n = 219) and HVTN 702 (n = 1611) trials. Most males reported no male sexual partners (99.09% in HVTN 503) or identified as heterosexual (88.08% in HVTN 702). Annual HIV incidence was 1.39% in HVTN 503 (95% CI 0.76–2.32%) and 1.33% in HVTN 702 (95% CI 0.80–2.07%). Increased HIV acquisition was significantly associated with anal sex (HR 6.32, 95% CI 3.44–11.62), transactional sex (HR 3.42, 95% CI 1.80–6.50), and non-heterosexual identity (HR 16.23, 95%CI 8.13–32.41) in univariate analyses and non-heterosexual identity (HR 14.99, 95% CI 4.99–45.04; p  〈  0.01) in multivariate analysis. It is appropriate that prevention efforts in South Africa, although focused on the severe epidemic in young women, also encompass key male populations, including men who have sex with men, but also men who engage in anal or transactional sex.
    Type of Medium: Online Resource
    ISSN: 1090-7165 , 1573-3254
    URL: Article
    DOI: 10.1007/s10461-023-04025-z
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2014832-X
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  • 6
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    Infection pre-Ad26.COV2.S-vaccination primes greater class switching and reduced CXCR5 expression by SARS-CoV-2-specific memory B cells
    Springer Science and Business Media LLC ; 2023
    In:  npj Vaccines Vol. 8, No. 1 ( 2023-08-12)
    Details
    In: npj Vaccines, Springer Science and Business Media LLC, Vol. 8, No. 1 ( 2023-08-12)
    Abstract: Neutralizing antibodies strongly correlate with protection for COVID-19 vaccines, but the corresponding memory B cells that form to protect against future infection are relatively understudied. Here we examine the effect of prior SARS-CoV-2 infection on the magnitude and phenotype of the memory B cell response to single dose Johnson and Johnson (Ad26.COV2.S) vaccination in South African health care workers. Participants were either naïve to SARS-CoV-2 or had been infected before vaccination. SARS-CoV-2-specific memory B-cells expand in response to Ad26.COV2.S and are maintained for the study duration (84 days) in all individuals. However, prior infection is associated with a greater frequency of these cells, a significant reduction in expression of the germinal center chemokine receptor CXCR5, and increased class switching. These B cell features correlated with neutralization and antibody-dependent cytotoxicity (ADCC) activity, and with the frequency of SARS-CoV-2 specific circulating T follicular helper cells (cTfh). Vaccination-induced effective neutralization of the D614G variant in both infected and naïve participants but boosted neutralizing antibodies against the Beta and Omicron variants only in participants with prior infection. In addition, the SARS-CoV-2 specific CD8+ T cell response correlated with increased memory B cell expression of the lung-homing receptor CXCR3, which was sustained in the previously infected group. Finally, although vaccination achieved equivalent B cell activation regardless of infection history, it was negatively impacted by age. These data show that phenotyping the response to vaccination can provide insight into the impact of prior infection on memory B cell homing, CSM, cTfh, and neutralization activity. These data can provide early signals to inform studies of vaccine boosting, durability, and co-morbidities.
    Type of Medium: Online Resource
    ISSN: 2059-0105
    URL: Article
    DOI: 10.1038/s41541-023-00724-9
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2882262-6
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  • 7
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    Emergence and phenotypic characterization of the global SARS-CoV-2 C.1.2 lineage
    Springer Science and Business Media LLC ; 2022
    In:  Nature Communications Vol. 13, No. 1 ( 2022-04-08)
    Details
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 13, No. 1 ( 2022-04-08)
    Abstract: Global genomic surveillance of SARS-CoV-2 has identified variants associated with increased transmissibility, neutralization resistance and disease severity. Here we report the emergence of the PANGO lineage C.1.2, detected at low prevalence in South Africa and eleven other countries. The initial C.1.2 detection is associated with a high substitution rate, and includes changes within the spike protein that have been associated with increased transmissibility or reduced neutralization sensitivity in SARS-CoV-2 variants of concern or variants of interest. Like Beta and Delta, C.1.2 shows significantly reduced neutralization sensitivity to plasma from vaccinees and individuals infected with the ancestral D614G virus. In contrast, convalescent donors infected with either Beta or Delta show high plasma neutralization against C.1.2. These functional data suggest that vaccine efficacy against C.1.2 will be equivalent to Beta and Delta, and that prior infection with either Beta or Delta will likely offer protection against C.1.2.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    URL: Article
    DOI: 10.1038/s41467-022-29579-9
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2553671-0
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  • 8
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    Novavax NVX-COV2373 triggers neutralization of Omicron sub-lineages
    Springer Science and Business Media LLC ; 2023
    In:  Scientific Reports Vol. 13, No. 1 ( 2023-01-21)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 13, No. 1 ( 2023-01-21)
    Abstract: The SARS-CoV-2 Omicron (B.1.1.529) Variant of Concern (VOC) and its sub-lineages (including BA.2, BA.4, BA.5, BA.2.12.1) contain spike mutations that confer high level resistance to neutralizing antibodies induced by vaccination with ancestral spike or infection with previously circulating variants. The NVX-CoV2373 vaccine, a protein nanoparticle vaccine containing the ancestral spike sequence, has value in countries with constrained cold-chain requirements. Here we report neutralizing titers following two or three doses of NVX-CoV2373. We show that after two doses, Omicron sub-lineages BA.1 and BA.4/BA.5 were resistant to neutralization by 72% (21/29) and 59% (17/29) of samples respectively. However, after a third dose of NVX-CoV2373, we observed high titers against Omicron BA.1 (GMT: 1,197) and BA.4/BA.5 (GMT: 582), with responses similar in magnitude to those triggered by three doses of an mRNA vaccine. These data are of particular relevance as BA.4/BA.5 is dominating in multiple locations, and highlight the potential utility of the NVX-CoV2373 vaccine as a booster in resource-limited environments.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-023-27698-x
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2615211-3
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