ICOS and infection: Both DENV-specific CD4+ and CD8+ T cells during acute phase of the disease ex-pressed multiple activation and inhibitory genes such as CTLA4, ICOS, LAG-3, HAVCR2 (encoding TIM-3) and IL-10 as well as effector molecules GZMB (encodes Granzyme B), and CCL4, suggesting that cytotoxic activity is exerted by both populations during acute phase of infection [29,53,54].