Comparison of Th-cell immunity against human bocavirus and parvovirus B19: proliferation and cytokine responses are similar in magnitude but more closely interrelated with human bocavirus.

Human parvovirus B19 (B19) has been, for decades, the only parvovirus known to be pathogenic in humans. Another pathogenic human parvovirus, human bocavirus (HBoV), was recently identified in respiratory samples from children with acute lower respiratory tract symptoms. Both B19 and HBoV are transmitted by the respiratory route. The vast majority of adults are IgG seropositive for HBoV, whereas the HBoV-specific Th-cell immunity has not much been studied. The aim of this study was to increase our knowledge on HBoV-specific Th-cell immunity by examining HBoV-specific T-cell proliferation, Interferon-gamma (IFN-γ), IL-10 and IL-13 responses in 36 asymptomatic adults. Recombinant HBoV VP2 virus-like particles (VLP) were used as antigen. HBoV-specific responses were compared with those elicited by B19 VP2 VLP. Proliferation, IFN-γ and IL-10 responses with HBoV and B19 antigens among B19-seropositive subjects were statistically similar in magnitude, but the cytokine and proliferation responses were much more closely correlated in HBoV than in B19. Therefore, at the collective level, B19-specific Th-cell immunity appears to be more divergent than the HBoV-specific one.