CD4 and infection: Together, these data described the increase in activation markers and cellular exhaustion, in addition to the reduction in functionality markers indicating that, like CD4+ T lymphocytes, these cells were probably hyperactivated right at the beginning of the infection, collaborating with the generation of a cytokine storm, until they became exhausted and lost their functional capacity, causing reduction of antigen-specific response and loss of its antiviral effects (Figure 2).