Reactivation of Simian Varicella Virus in Rhesus Macaques after CD4 T Cell Depletion.

Rhesus macaques intrabronchially inoculated with simian varicella virus (SVV), the counterpart of human varicella-zoster virus (VZV), developed primary infection with viremia and rash, which resolved upon clearance of viremia, followed by the establishment of latency. To assess the role of CD4 T cell immunity in reactivation, monkeys were treated with a single 50-mg/kg dose of a humanized monoclonal anti-CD4 antibody; within 1 week, circulating CD4 T cells were reduced from 40 to 60% to 5 to 30% of the total T cell population and remained low for 2 months. Very low viremia was seen only in some of the treated monkeys.