CD4 and viral infectious disease: Intra-nasal immunization with N SRS was specifically associated with the presence of CD4+CD69+ lymphocytes as early as 4 days and up to 10 days after virus infection (Fig. 6C), as compared with non vaccinated or LT(R192G) immunized mice where CD8+CD69+ lymphocytes were the predominant subset (Fig. 6C).