Vaccine-Induced Seroreactivity Impacts the Accuracy of HIV Testing Algorithms in Sub-Saharan Africa: An Exploratory Study.

The detection of vaccine-induced HIV antibody responses by rapid diagnostic tests (RDTs) may confound the interpretation of HIV testing results. We assessed the impact of vaccine-induced seroreactivity (VISR) on the diagnosis of HIV in sub-Saharan Africa. Samples collected from healthy participants of HIVIS and TaMoVac HIV vaccine trials after the final vaccination were analyzed for VISR using HIV testing algorithms used in Mozambique and Tanzania that employ two sequential RDTs. The samples were also tested for VISR using Enzygnost HIV Integral 4 ELISA and HIV western blot assays. Antibody titers to subtype C gp140 were determined using an in-house enzyme-linked immunosorbent assay (ELISA). The frequency of VISR was 93.4% (128/137) by Enzygnost HIV Integral 4 ELISA, and 66.4% (91/137) by western blot assay (WHO interpretation). The proportion of vaccine recipients that would have been misdiagnosed as HIV-positive in Mozambique was half of that in Tanzania: 26.3% (36/137) and 54.0% (74/137), respectively, p < 0.0001. In conclusion, the HIV RDTs and algorithms assessed here will potentially misclassify a large proportion of the HIV vaccine recipients if no other test is used. Increased efforts are needed to develop differential serological or molecular tools for use at the point of care.

Tuberculosis Treatment Response Monitoring by the Phenotypic Characterization of MTB-Specific CD4+ T-Cells in Relation to HIV Infection Status.

HIV infection causes systemic immune activation, impacts TB disease progression and hence may influence the diagnostic usability of Mycobacterium tuberculosis-specific T cell profiling. We investigated changes of activation and maturation markers on MTB-specific CD4+ T-cells after anti-tuberculosis treatment initiation in relation to HIV status and the severity of lung impairment. Thawed peripheral blood mononuclear cells from TB patients with (n = 27) and without HIV (n = 17) were analyzed using an intracellular IFN-γ assay and flow cytometry 2 and 6 months post-TB treatment initiation. H37Rv antigen was superior to the profile MTB-specific CD4+ T-cells phenotype when compared to PPD and ESAT6/CFP10. Regardless of HIV status and the severity of lung impairment, activation markers (CD38, HLA-DR and Ki67) on MTB-specific CD4+ T-cells declined after TB treatment initiation (p < 0.01), but the expression of the maturation marker CD27 did not change over the course of TB treatment. The MTB-specific T cell phenotype before, during and after treatment completion was similar between people living with and without HIV, as well as between subjects with severe and mild lung impairment. These data suggest that the assessment of activation and maturation markers on MTB-specific CD4+ T-cells can be useful for TB treatment monitoring, regardless of HIV status and the severity of lung disease.

Determining hematological, biochemical and immunological reference values in healthy adults with high-risk for HIV acquisition in Mozambique.

INTRODUCTION: In many African countries, laboratory reference values are not established for the local healthy adult population. In Mozambique, reference values are known for young adults (18-24yo) but not yet established for a wider age range. Our study aimed to establish hematological, biochemical and immunological reference values for vaccine trials in Mozambican healthy adults with high-risk for HIV acquisition. METHODS: A longitudinal cohort and site development study in Mozambique between November 2013 and 2014 enrolled 505 participants between 18 to 35 years old. Samples from these healthy participants, were analyzed to determine reference values. All volunteers included in the analysis were clinically healthy and human immunodeficiency virus (HIV), hepatitis B and C virus, and syphilis negative. Median and reference ranges were calculated for the hematological, biochemical and immunological parameters. Ranges were compared with other African countries, the USA and the US National Institute of Health (NIH) Division of AIDS (DAIDS) toxicity tables. RESULTS: A total of 505 participant samples were analyzed. Of these, 419 participants were HIV, hepatitis B and C virus and syphilis negative including 203 (48.5%) females and 216 (51.5%) males, with a mean age of 21 years. In the hematological parameters, we found significant differences between sex for erythrocytes, hemoglobin, hematocrit, MCV, MCH and MCHC as well as white blood cells, neutrophils and platelets: males had higher values than females. There were also significant differences in CD4+T cell values, 803 cells/µL in men versus 926 cells/µL in women. In biochemical parameters, men presented higher values than women for the metabolic, enzymatic and renal parameters: total and direct bilirubin, ALT and creatinine. CONCLUSION: This study has established reference values for healthy adults with high-risk for HIV acquisition in Mozambique. These data are helpful in the context of future clinical research and patient care and treatment for the general adult population in the Mozambique and underline the importance of region-specific clinical reference ranges.

Frequent Anti-V1V2 Responses Induced by HIV-DNA Followed by HIV-MVA with or without CN54rgp140/GLA-AF in Healthy African Volunteers.

Antibody responses that correlated with reduced risk of HIV acquisition in the RV144 efficacy trial were assessed in healthy African volunteers who had been primed three times with HIV-DNA (subtype A, B, C) and then randomized into two groups; group 1 was boosted twice with HIV-MVA (CRF01_AE) and group 2 with the same HIV-MVA coadministered with subtype C envelope (Env) protein (CN54rgp140/GLA-AF). The fine specificity of plasma Env-specific antibody responses was mapped after the final vaccination using linear peptide microarray technology. Binding IgG antibodies to the V1V2 loop in CRF01_AE and subtype C Env and Env-specific IgA antibodies were determined using enzyme-linked immunosorbent assay. Functional antibody-dependent cellular cytotoxicity (ADCC)-mediating antibody responses were measured using luciferase assay. Mapping of linear epitopes within HIV-1 Env demonstrated strong targeting of the V1V2, V3, and the immunodominant region in gp41 in both groups, with additional recognition of two epitopes located in the C2 and C4 regions in group 2. A high frequency of V1V2-specific binding IgG antibody responses was detected to CRF01_AE (77%) and subtype C antigens (65%). In conclusion, coadministration of CN54rgp140/GLA-AF with HIV-MVA did not increase the frequency, breadth, or magnitude of anti-V1V2 responses or ADCC-mediating antibodies induced by boosting with HIV-MVA alone.

Regulatory T cell abundance and activation status before and after priming with HIVIS-DNA and boosting with MVA-HIV/rgp140/GLA-AF may impact the magnitude of the vaccine-induced immune responses.

BACKGROUND: Little is known about regulatory CD4 T cells (Tregs) in the context of HIV vaccines. Tregs can be differentiated into resting (FoxP3+CD45RA+ - rTregs), activated (FoxP3HighCD45RA- - aTregs) and memory (FoxP3LowCD45RA- - mTregs). Tregs, as CD4 T cells, are also frequent targets for HIV infection. We studied how the abundance and phenotypes of Tregs in terms of activation status and expression of HIV-1 binding molecules would have changed during vaccination in healthy volunteers participating in a phase IIa HIV vaccine clinical trial. Subjects were primed three times with HIVIS-DNA and boosted twice with MVA-CMDR-HIV alone (n = 12) or MVA-CMDR combined with protein CN54rgp140 (n = 13). The proportions of ß7 integrin in all CD4 T cells and in the Tregs subset decreased moderately after the final vaccination (p = 0.001 and p = 0.033, respectively) and the rTregs proportion within the total Tregs were also decreased after the final vaccination (p = 0.038). All these proportions returned to normal values within the three months after the final vaccination. The magnitude of HIV-Envelope-specific IFNγ + T cells after vaccination (r = 0.66; p = 0.021) correlated directly with the proportion of Tregs, and correlated inversely correlated with ratios of Th17/Tregs (r = -0.75; p = 0.0057) and Th17/mTregs (r = -0.78; p = 0.0065). Higher titers of IgG gp140 antibodies were observed in subjects with higher mTregs proportions (r = 0.52; p = 0.022). Interestingly, pre-vaccination levels of mTregs correlated with vaccine-induced Env-binding antibodies (r = 0.57; p = 0.01) and presence of neutralizing antibodies (r = 0.61; p = 0.01), while the pre-vaccination Th17/mTregs ratio correlated inversely with the magnitude of cellular IFN-γ ELISpot responses (r = -0.9; p = 0.002). Taken together, these results suggest that pre- and post-vaccination Tregs, their activation status, the Th17/Tregs ratio and other host factors affecting Treg abundance, have an impact on the magnitude of HIV vaccine-induced immune responses. Moreover, the DNA-HIVIS/MVA-HIV regimen, alone or in combination with CN54rgp140 induced moderate and temporary alterations of the Tregs activation status. We also show a decrease in expression of the HIV-1 ligand ß7 integrin on Tregs and all CD4 T cells.