Researcher: Ms Bongiwe Ndlovu.

Designation: Lecturer

Study: Evolution of Neutralising Antibodies in HIV-1 Subtype C Infection

Summary: Background: The development of a preventative HIV-1 vaccine will most likely require induction of broadly neutralizing antibodies (BCN). However, the mechanism that leads to the development of BCN is unknown and not all epitopes have been identified. The aim of the study was to evaluate pathways and mechanisms that lead to the development of broadly neutralizing antibodies.

Methods: Twenty individuals with acute HIV-1 infection were identified and followed longitudinally for three years in Durban, KwaZulu-Natal. A panel of 18 viruses (6 subtype A, 6B and 6C) was used to screen the patients for neutralizing antibodies using the TZM-bl neutralization assay. The patients that developed broadly neutralizing antibodies were followed up longitudinally to determine the timing of emergence of the BCNs. Specificity of BCNs was determined using single point mutagenesis at 3 years post-infection.

Results: Three out of 20 individuals (AS3-268, AS2-1037, AS2-358) developed broadly neutralizing antibodies. AS3-268 developed potent BCN activity peaking at 3 years post-infection and it targets N276A glycan on the CD4 binding site of gp120. AS2-1037 developed potent broadly neutralizing activity peaking at 2 years post-infection and it targets N332A glycan on the V3 loop of gp120. AS2-358 developed BCNs peaking at 2 years post-infection and it did not map to any known specific epitope.

Conclusion: Broadly neutralizing antibodies could be detected at approximately 1 year post-infection and they targeted different epitopes on the viral envelope. Work is currently in progress to assess the maturation of breadth and to assess antibody-virus co-evolution.



Researcher: Ms Bongiwe Ndlovu

Designation: Lecturer

Study: Use of dried blood spots for the determination of genetic variation of interleukin-10, killer immunoglobulin-like receptor and HLA class I genes

Summary: 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.

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