IFNG and infection: Virus-specific IFN-γ+ effector CD8+ T cells were recruited in the lungs of both groups; however, infection with the MAp2009 virus was associated with remarkably weaker NP- and PA-specific CD8+ T cell responses (Fig 5C and 5D, P<0.05 and P< 0.001, respectively) that was maintained over the course of the response (until day 14 p.i.).