CCR4 and Lassa fever: In agreement with the findings in LF patients, the severities of disease after inoculation by intranasal and oral routes in the mouse model were correlated with increases in the frequencies of circulating T cells with homing signatures for the respiratory mucosa (CCR3 and CCR4) and the gut (ITGA4B7) (Fig. 6F), which suggests that the identification of circulating T cells with defined homing markers during acute LF may provide useful information about routes of infection.