IL4 and infection: In order to find out, whether the suppressed IFN-γ response at 20 weeks post-infection in spleen of MST22 infected mice was the result of a shift from Th1 to Th2, Th17 or Treg helper T cell phenotype, we measured the production of IL-4, IL-10, IL-17 and IL-1β by ELISA in week 5 and week 20 spleen cell culture supernatants of mice infected with the two MST22 and the two MST91 isolates.