Evidence of Latent Varicella-Zoster Virus in Rat Dorsal Root Ganglia

Latent varicella-zoster virus (VZV) was studied in ganglia of rats that had been inoculated subcutaneously with either a high-passaged wild-type, a low-passaged wild-type, or the vaccine strain of virus using in situ hybridization. Nine of 11 rats injected with virus and no control rats developed serum VZV antibodies as demonstrated by fluorescent antibody membrane antigen. Polymerase chain reaction 2 weeks following inoculation did not detect viremia in the rats. VZV was detected by in situ hybridization in ganglia of 10 of the 11 infected rats but not in ganglia of the control rats. The distribution of VZV DNA is identical to that seen in humans; satellite cells and neurons contain VZV DNA. Although all animals received unilateral injections of virus, VZV DNA was in ipsilateral and contralateral ganglia in 6 animals, suggesting that virus replication and viremia had occurred.