CD8A and infection: ,39 Although plasma vRNA was not detected in the LEN PrEP animals as LEN levels declined well below the PA-EC95, to definitively confirm that infection was prevented in the LEN PrEP animals, we administered an in vivo cell-depleting anti-CD8α antibody to the LEN PrEP animals at 419 days post-challenge, when LEN was no longer detected in plasma (Fig. 5a).