Balance between activation and regulation of HIV-specific CD8+ T-cell response after modified vaccinia Ankara B therapeutic vaccination

Balance between activation and regulation of HIV-specific CD8+ T-cell response after modified vaccinia Ankara B therapeutic vaccination

Printed publication: 20 February 2016 Journal: AIDS

Abstract:

BACKGROUND: The causes of HIV-vaccines failure are poorly understood. Therapeutic vaccination with modified vaccinia Ankara (MVA)-B in HIV-1-infected individuals did not control the virus upon analytical treatment interruption (ATI). We investigated whether the functional characteristics of HIV-specific CD8 T-cell responses stimulated by this vaccine, and the level of exhaustion of these cells might explain these results.

METHODS:Twenty-one HIV-1 chronically infected patients on combination antiretroviral therapy, included in the therapeutic vaccine trial RISVAC03, were studied: 13 immunized and eight controls. Functional characteristics, cytotoxic potential and exhaustion of HIV-specific CD8 T cells, were evaluated by polychromatic flow cytometry. Differences between groups were tested using nonparametric tests.

RESULTS: MVA-B vaccine induced an increase in HIV-specific CD8 T-cell response, but also increased their levels of exhaustion. At week 18 (following three immunizations) the level of response increased with respect to baseline (P = 0.02). A significant increase at weeks 18 and 24 (ATI) in granzyme B content was also observed. Interestingly, an increase in expression of exhaustion markers was found at weeks 18 (P = 0.006) and 24 (P = 0.01). However, there was no significant change in the functional profile of vaccine-induced CD8 cells. At week 36, in parallel to the rebound of plasma viremia after 12 weeks ATI, a significant increase in the level of CD8 response, in granzyme B content and in exhaustion markers expression, was observed in both groups.

CONCLUSION: We show that therapeutic vaccination with MVA-B tilts the balance between activation and regulation of the response of HIV-specific CD8 T cells towards regulation, which impacts on the viral rebound after ATI.

Authors: Rallón N, Mothe B, Lopez Bernaldo de Quiros JC, Plana M, Ligos JM, Montoya M, Muñoz-Fernández MA, Esteban M, Garcia F, Brander C, Benito JM; RISVAC03 Study Group.

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