CD8A and infection: When we monitored cellular infiltrate in the lung post M.tb challenge in mice vaccinated by the heterologous prime boost protocol we observed that whereas high numbers of both H4 specific CD4 and CD8 T cells were promoted by the vaccine, the CD4 T cells showed accelerated recruitment to the site of infection compared to CD8 cells and importantly CD4 cells were the main subset proliferating in the lung in response to M.tb infection in the vaccinated animals.