CD4 and infection: Moreover, RSV-A–specific and RSV-B–specific CD4+ T-cell frequencies above the LLoQ by individual subjects were positively correlated (r=0.91), irrespective of whether the infections were by RSV-A or RSV-B, suggesting that the epitopes that were recognized by those CD4+ T cells appeared to be conserved between RSV A and RSV B (Figure 1B).