|Call||Career Development Fellowship (CDF)|
Neutralization of HIV-1 subtype C transmitted or founder viruses by broadly neutralizing monoclonal antibodies
University of KwaZulu-Natal
|2021||9th Norman L. Letvin Early Career Investigator Award|
|Type||Name||Title||University||Start Date||End Date|
|Masters||Ntokozo Ntshangase||Ms||University of KwaZulu-Natal||2019||2022|
|Masters||Kim Robertson||Ms||University of KwaZulu-Natal||2015||2020|
|Masters||Silondoloze Ntshangase||Ms||University of KwaZulu-Natal||2022|
|Masters||Langelihle Mlambo||Ms||University of KwaZulu-Natal||2022|
|Masters||Keyura Velan||Ms||University of KwaZulu-Natal||2023|
|PhD||Nelisiwe Zikhali||Ms||University of KwaZulu-Natal||2020|
|PhD||Yanga Mdleleni||Ms||University of KwaZulu-Natal||2019|
|PhD||Tawanda Chisango||Dr.||University of KwaZulu-Natal||2016||2018|
|Masters||Nzuzo Magini||Mr||University of KwaZulu-Natal||2019||2021|
|University of KwaZulu-Natal, South Africa||PhD||2017-04-17|
Human Immuno-deficiency Virus (HIV)
Background: Schistosomiasis is a devastating parasitic disease. The mainstay of schistosomiasis control is by
praziquantel treatment. The study aimed to determine benefits of annual chemotherapy of schistosomiasis on
development of protective immunity in school children in a selected endemic rural area in Zimbabwe.
Methods: Urine specimens from 212 school children (7–13 years) were collected and examined to determine
prevalence, intensity and reinfection of S.haematobium at baseline, 6 weeks and 2 years following annual rounds of
praziquantel treatment. Blood samples from the participants were assayed for total and S. haematobium (Sh13)-specific
antibodies before and 2 years after annual rounds of treatment.
Results: Annual treatment reduced the prevalence of S. haematobium infection (p < 0.05) from 23.1% at baseline to 0.
47% after 2 years. Overall cure rate was 97.8%. Intensity of infection declined (p < 0.05) from 15.9 eggs/10 ml urine at
baseline to 2 eggs/10 ml urine. After two years, overall rate of reinfection was 0.96%. At baseline, total IgG4 was higher
in S. haematobium-infected children (p = 0.042) ,while all other immunoglobulins were within normal ranges. There
was an increase in total IgG2 (p = 0.044) levels and a decrease in total IgG4 (p = 0.031) levels 2 years post-treatment;
and no significant changes in other total immunoglobulins. Schistosoma-infected children at baseline showed an
increase in anti-Sh13 IgG1 (p = 0.005) and a decrease in Sh13 IgG4 levels (p = 0.012) following treatment.
Conclusion: Annual praziquantel treatment delivered to school children over 2 years significantly reduce prevalence,
intensity of infection and reinfection of S. haematobium infection. Treatment was also observed to cause a reduction in
schistosome-specific blocking IgG4 and an increase in Schistosoma-specific protecting IgG1.
The RV144 HIV-vaccine trial highlighted the importance of envelope-specific non-neutralizing antibody (nNAb) Fc-mediated functions as immune correlates of reduced risk of infection. Since pre-exposure prophylaxis (PrEP) and HIV-vaccines are being used as a combination prevention strategy in at risk populations, the effects of PrEP on nNAb functions both mucosally and systemically remain undefined. Previous animal and human studies demonstrated reduced HIV-specific antibody binding avidity post-HIV seroconversion with PrEP, which in turn may affect antibody functionality. In seroconverters from the CAPRISA 004 tenofovir gel trial, we previously reported significantly higher detection and titres of HIV-specific binding antibodies in the plasma and genital tract (GT) that distinguished the tenofovir from the placebo arm. We hypothesized that higher HIV-specific antibody titres and detection reflected corresponding increased antibody-dependent neutrophil-mediated phagocytosis (ADNP) and NK-cell-activated antibody-dependent cellular cytotoxic (ADCC) activities. HIV-specific V1V2-gp70, gp120, gp41, p66, and p24 antibodies in GT and plasma samples of 48 seroconverters from the CAPRISA 004 tenofovir gel trial were tested for ADCP and ADCC at 3, 6- and 12-months post-HIV-infection. GT gp41- and p24-specific ADNP were significantly higher in the tenofovir than the placebo arm at 6 and 12 months respectively (p < 0.05). Plasma gp120-, gp41-, and p66-specific ADNP, and GT gp41-specific ADCC increased significantly over time (p < 0.05) in the tenofovir arm. In the tenofovir arm only, significant inverse correlations were observed between gp120-specific ADCC and gp120-antibody titres (r = −0.54; p = 0.009), and gp41-specific ADNP and gp41-specific antibody titres at 6 months post-infection (r = −0.50; p = 0.015). In addition, in the tenofovir arm, gp41-specific ADCC showed significant direct correlations between the compartments (r = 0.53; p = 0.045). Certain HIV-specific nNAb activities not only dominate specific immunological compartments but can also exhibit diverse functions within the same compartment. Our previous findings of increased HIV specific antibody detection and titres in women who used tenofovir gel, and the limited differences in nNAb activities between the arms, suggest that prior PrEP did not modulate these nNAb functions post-HIV seroconversion. Together these data provide insight into envelope-specific-nNAb Fc-mediated functions at the site of exposure which may inform on ensuing immunity during combination HIV prevention strategies including PrEP and HIV vaccines.
Optimal methods for using dried blood spots (DBSs) for population genetics-based studies have not been well established. Using DBS stored for 8 years from 21 pregnant South African women, we evaluated three methods of gDNA extraction with and without whole-genome amplification (WGA) to characterize immune-related genes: interleukin-10 (IL-10), killer immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) class I. We found that the QIAamp DNA mini kit yielded the highest gDNA quality (P< 0.05; Wilcoxon signed rank test) with sufficient yield for subsequent analyses. In contrast, we found that WGA was not reliable for sequence-specific primer polymerase chain reaction (SSP-PCR) analysis of KIR2DL1, KIR2DS1, KIR2DL5 and KIR2DL3 or high-resolution HLA genotyping using a sequence-based approach. We speculate that unequal template amplification by WGA underrepresents gene repertoires determined by sequence-based approaches.
Post-infection HIV viral control and immune correlates analysis of the RV144 vaccine trial indicate a potentially critical role for Fc receptor-mediated antibody functions. However, the influence of functional antibodies in clade C infection is largely unknown.
Plasma samples from 361 chronic subtype C-infected, antiretroviral therapy-naïve participants were tested for their HIV-specific isotype and subclass distributions, along with their Fc receptor-mediated functional potential.
Total IgG, IgG subclasses and IgA binding to p24 clade B/C and gp120 consensus C proteins were assayed by multiplex. Antibody-dependent uptake of antigen-coated beads and Fc receptor-mediated NK cell degranulation were evaluated as surrogates for antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cellular cytotoxicity (ADCC) respectively.
p24 IgG1 was the only subclass associated with viral control (p=0.01), with higher p24-specific ADCP and ADCC responses detected in individuals with high p24 IgG1. Although p24 IgG1 levels were enriched in subjects with elevated Gag-specific T cell responses, these levels remained an independent predictor of low viral loads (p=0.04) and high CD4 counts (p=0.004) after adjusting for Gag-specific T cell responses and for protective HLA class I alleles.
p24 IgG1 levels independently predict viral control in HIV-1 clade C infection. Whether these responses contribute to direct antiviral control via the recruited killing of infected cells via the innate immune system or simply mark a qualitatively superior immune response to HIV, is uncertain, but highlights the role of p24-specific antibodies in control of clade C HIV-1 infection.
Broadly neutralizing antibodies (bNAbs) for HIV-1 prevention or cure strategies must inhibit transmitted/founder and reservoir viruses. Establishing sensitivity of circulating viruses to bNAbs and genetic patterns affecting neutralization variability may guide rational bNAbs selection for clinical development. We analyzed 326 single env genomes from nine individuals followed longitudinally following acute HIV-1 infection, with samples collected at ~1 week after the first detection of plasma viremia; 300 to 1,709 days postinfection but prior to initiating antiretroviral therapy (ART) (median = 724 days); and ~1 year post ART initiation. Sequences were assessed for phylogenetic relatedness, potential N- and O-linked glycosylation, and variable loop lengths (V1 to V5). A total of 43 env amplicons (median = 3 per patient per time point) were cloned into an expression vector and the TZM-bl assay was used to assess the neutralization profiles of 15 bNAbs targeting the CD4 binding site, V1/V2 region, V3 supersite, MPER, gp120/gp41 interface, and fusion peptide. At 1 μg/mL, the neutralization breadths were as follows: VRC07-LS and N6.LS (100%), VRC01 (86%), PGT151 (81%), 10-1074 and PGT121 (80%), and less than 70% for 10E8, 3BNC117, CAP256.VRC26, 4E10, PGDM1400, and N123-VRC34.01. Features associated with low sensitivity to V1/V2 and V3 bNAbs were higher potential glycosylation sites and/or relatively longer V1 and V4 domains, including known "signature" mutations. The study shows significant variability in the breadth and potency of bNAbs against circulating HIV-1 subtype C envelopes. VRC07-LS, N6.LS, VRC01, PGT151, 10-1074, and PGT121 display broad activity against subtype C variants, and major determinants of sensitivity to most bNAbs were within the V1/V4 domains.
Objective: There is an increased risk of cases of direct and indirect morbidities as a result of stimulation of
tissue-destructive inflammation caused by Schistosoma haematobium infection, hence the need to determine the
levels of inflammatory markers in Schistosoma haematobium infected children and also determine the effect of
repeated annual mass treatment on levels of interleukin-6 and acute phase proteins.
Methodology: Urine specimens from 212 school children were collected and examined to determine prevalence
of Schistosoma haematobium at baseline and 2 years following annual rounds of praziquantel treatment. Levels of 4
acute phase proteins were measured from serum samples from the participants using the magnetic bead-based
immuno-assays at baseline and 2 years following praziquantel treatment. Sandwich enzyme-linked immunosorbent
assay was used to determine levels of interleukin-6.
Results: The overall pre-treatment prevalence of Schistosoma haematobium infection was 23.1% at baseline
and 0.47% after 2 years of annual treatments. Schistosoma haematobium infected children had marginally higher
levels of procalcitonin and tissue plasminogen activator before treatment though the difference of all three was not
significant p>0.05 using Mann-Whitney non-parametric U test. Levels of ferritin and fibrinogen were lower in
Schistosoma haematobium infected children before treatment, however the difference was also not significant
p>0.05 using Mann-Whitney test. There was no association between infection status or interleukin-6 and the levels
acute phase proteins p>0.05 for all acute phase proteins using the Mann-Whitney U test.
Discussion and Conclusion: Findings from this study suggest no bearing of Schistosoma haematobium
infection status on level of acute phase proteins before and after annual treatment with praziquantel. The extent of
inflammation cannot be determined using ferritin, tissue plasminogen activator and fibrinogen. Levels of interleukin-6
did not have any bearing on levels of acute phase proteins. There is a need to explore other acute phase proteins as
inflammatory markers in Schistosoma haematobium infection.
Broadly neutralizing antibodies (bNAbs) may constitute an essential component of a protective vaccine against HIV-1, yet no immunogen has been able to elicit them. To characterize the development of bNAbs in HIV-1 subtype C infected individuals, a panel of 18 Env-pseudotyped viruses was used to screen 18 study participants. The specificity of plasma neutralization was mapped against Env mutants and MPER chimeras. Envelope (env) gene sequence evolution was characterized by single genome amplification and sequencing. Three out of eighteen individuals developed broad plasma neutralizing activity (>60% breadth). Two of the three participants may target epitopes comprising glycans at position 276 of the D loop in the CD4 binding site and 332 glycan supersite, respectively. Deletion of these glycans was associated with neutralization resistance. Our study describes the kinetics of the development of plasma neutralizing activity and identified amino acid residue changes suggestive of immune pressure on putative epitopes. The study enhances our understanding of how neutralization breadth develops in the course of HIV-1 subtype C infection.
Despite decades of focused research, the field has yet to develop a prophylactic vaccine for HIV-1 infection. In the RV144 vaccine trial, nonneutralizing antibody responses were identified as a correlate for prevention of HIV acquisition. However, factors that predict the development of such antibodies are not fully elucidated. We sought to define the contribution of circulating T follicular helper (cTfh) subsets to the development of nonneutralizing antibodies in HIV-1 clade C infection. Study participants were recruited from an acute HIV-1 clade C infection cohort. Plasma anti-gp41, -gp120, -p24, and -p17 antibodies were screened using a customized multivariate Luminex assay. Phenotypic and functional characterizations of cTfh cells were performed using HLA class II tetramers and intracellular cytokine staining. In this study, we found that acute HIV-1 clade C infection skewed the differentiation of functional cTfh subsets toward increased Tfh1 (P = 0.02) and Tfh2 (P < 0.0001) subsets, with a concomitant decrease in overall Tfh1-17 (which shares both Tfh1 and Tfh17 properties) (P = 0.01) and Tfh17 (P < 0.0001) subsets, compared to the subsets found in HIV-negative subjects. Interestingly, the frequencies of Tfh1 cells during acute infection (5.0 to 8.0 weeks postinfection) correlated negatively with the set point viral load (P = 0.03, Spearman rho [r] = -60) and were predictive of p24-specific plasma IgG titers at 1 year of infection (P = 0.003, r = 0.85). Taken together, our results suggest that the circulating Tfh1 subset plays an important role in the development of anti-HIV antibody responses and contributes to HIV suppression during acute HIV-1 infection. These results have implications for vaccine studies aimed at inducing long-lasting anti-HIV antibody responses
|Dr. Bongiwe Ndlovu||South Africa||University of KwaZulu-Natal|