Fig. 5

Immunization results in alterations in lymphoid immunophenotype in vaccinated cats. Prior to FIV challenge in Protocol II studies, CD8+ (a) CD4+ (b), and B220+ (c) lymphocytes were significantly elevated in CD134+SU vaccinated cats compared to CD134 vaccinated cats (p < 0.03, p < 0.04, p < 0.03, respectively). CD4+ and B220+ cell levels were slightly higher in CD134+SU vaccinated cats compared to Sham vaccinated cats prior to FIV challenge, and there was a trend for CD8+ cells to be decreased (p = 0.081) in CD134 vaccinated cats. d In CD134+SU vaccinated cats, decreased CD4:CD8 ratios prior to FIV challenge correlated with higher proviral DNA loads during acute stages of FIV infection, indicating that changes induced in circulating T-cell populations by vaccination-associated immunostimulation may predispose to enhanced susceptibility to viral infection (p = 0.05, R² = 0.89)