Vaccine-elicited CD4 T cells prevent the deletion of antiviral B cells in chronic infection

CD4 T cells responses induced by LM61 immunization are heterogeneous in phenotype. The majority consists of Th1 cells, but there is also a consistent population of Tfh-differentiated cells and a minor population of Treg cells. Tfh-differentiated cells, alongside Th1 cells expand upon LCMV challenge. LCMV GP66-77-specific CD4 T cells were analyzed on day 9 after LM61 immunization. Additional mice were given KL25HL B cell transfer and LCMV challenge on day 9 after LM61 immunization and GP66-77-specific CD4 T cells were analyzed on day 14. To control for the impact of LM61 pre-immunization on the differentiation of GP66-77-specific CD4 T cell responses upon LCMV challenge, an additional group of mice was given wildtype LM on day 0 instead of LM61.