Evaluation of T and B memory cell responses elicited by the pandemic H1N1 vaccine in HIV-infected and HIV-uninfected individuals

Background: This study was to compare B and T memory cells elicited by a single dose monovalent 2009 influenza A (H1N1) vaccine (strain A/California/7/2009 H1N1) in HIV+ and HIV- groups, and to analyze the impact of the prior seasonal vaccines to the immunogenicity of this vaccine. Methods: Blood samples were collected before vaccination (day 0) and at days 28 and 180. Participants were categorized into HIV-/LAIV, HIV-/TIV and HIV+/TIV subgroups according to the trivalent live attenuated or inactivated (LAW or TIV) seasonal influenza vaccines they received previously. The IgG(+) memory B cells (B-Mem) and IFN gamma(+) T cells were measured against antigens including the H1N1 vaccine, the hemagglutinin (HA) and neuraminidase (NA) proteins or peptide pools of the pandemic and the seasonal H1N1 strains, respectively. Results: Overall B-Mem responses increased significantly at day 28 but returned to baseline by day 180 in all three subgroups. The average frequency of the H1N1-specific B-Mem at day 28 for the HIV-/LAIV, HIV-/TIV and HIV+/TIV groups was 2.14%, 1.26% and 1.67%, respectively, and the average fold change was 14.39, 3.81 and 3.93, respectively. The differences of B-Mem between HIV-/LAIV and the two TIV subgroups were significant. For the IFN gamma response, the overall spot counts ranged widely between 0 and 958/10(6) PBMCs. The group average spot counts to H1N1 vaccine was 89, 102, and 30 at day 28 for HIV-/LAIV, HIV-/TIV and HIV+/TIV subgroups, respectively. The average increase of IFN gamma response at day 28 vs day 0 in all three subgroups did not reach 2-fold. Conclusion: Participants with a prior LAIV seasonal vaccine, as compared to a TIV seasonal vaccine, responded significantly better to the monovalent H1N1 vaccine. Excluding LAIV participants, no difference was seen between the HIV+ and HIV- subject groups in terms of B-Mem. The B-Mem response declined at 6 months. (C) 2017 Published by Elsevier Ltd.