CD4 and neutropenia: The loss of peripheral CD4 T cells and increased PVL detected at day 14 and day 7 post-SIV infection, respectively, as well as neutropenia seen from day 3 to day 14 in SIV-infected RhMs, suggest that the early loss of neutrophil-mediated primary defense has a significant impact on initial virus replication and the loss of peripheral CD4+ T cells.