GZMB and Epstein-Barr virus infection: Therefore, as little is known about the response of local cytotoxic and regulatory CD4 T cells in EBV primary and persistent infection in pediatric patients, from developed as well as undeveloped populations, our aim was to evaluate the presence of GZMB+ and Foxp3+ CD4 T cells at different EBV infections statuses as well as in relation to different latency profiles in an undeveloped population.