Induction of circulating T follicular helper cells and regulatory T cells correlating with HIV-1 gp120 variable loop antibodies by a subtype C prophylactic vaccine tested in a Phase I trial in India.

Ponnan, S.M.; Swaminathan, S.; Kannan, T.; Vidya Vijayan, K.K.; Narayanaiah, C.; Nesakumar, M.; Kathirvel, S.; Goyal, R.; Singla, N.; Mukherjee, J.; Bergin, P.; Kopycinski, J.T.; Gilmour, J.; Tripathy, S.P.; Hanna, L.E.

PLoS One; 2018; 13(8): e0203037.

Abstract: A Phase I HIV-1 vaccine trial sponsored by the International AIDS Vaccine Initiative (IAVI) was conducted in India in 2009 to test a subtype C prophylactic vaccine in a prime-boost regimen comprising of a DNA prime (ADVAX) and MVA (TBC-M4) boost. The trial demonstrated that the regimen was safe and well tolerated and resulted in enhancement of HIV specific immune responses. Preliminary observations on vaccine-induced immune responses were limited to analysis of neutralizing antibodies and IFN-?ELISPOT response. The present study involves a more detailed analysis of the nature of the vaccine-induced humoral immune response using specimens that were archived from the volunteers at the time of the trial. Interestingly, we found vaccine induced production of V1/V2 and V3 region specific antibodies in a significant proportion of vaccinees. Variable region antibody levels correlated directly with the frequency of circulating T follicular helper cells (Tfh) and regulatory T cells (Treg). Our findings provide encouraging evidence to demonstrate the immunogenicity of the tested vaccine. Better insights into vaccine-induced immune responses can aid in informing future design of a successfulHIV-1 vaccine.

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