Investigation of the pathogenesis of varicella-zoster virus infection in guinea pigs using polymerase chain reaction

The polymerase chain reaction method (PCR) was used to investigate events in the pathogene-sis of varicella-zoster virus (VZV) infection in strain 2, Hartley, and euthymic hairless guinea pigs. VZV was detected in peripheral blood mononuclear cells (PBMC) obtained 2-5 days after infection in 8 (50%)of 16 strain 2, 4 (40%)of 10hairless, and 10 (34%)of 29 Hartley guinea pigs. The frequencyofVZV-infected PBMC wasestimated to be at least 1/200,000, which is compara-ble to that observed in human infection. When VZV PCR was used to test ganglia from hairless guinea pigs, samples from 6 of8 animals werepositive.Of 45 VZV-infectedguinea pigs that were tested for cellular immunity by VZV T lymphocyte proliferation assay, 44 developed a stimula-tion index>2.0. Control animals had no detectable virus by PCR and did not develop cellular immunity to VZV. These experiments showed that viremia was detectable by PCR during pri-mary VZV infection of guinea pigs in about half of the animals regardless of the strain of guinea pig. Acquisition of cellular immunity provided a consistent marker of infection in all guinea pig strains. PCR was also useful for demonstrating VZV in guinea pig ganglia tissue, with VZV gene sequences being detectable for at least 80 daysafter infection. With the combination of PCR and immunologic assays,various guinea pig strains should be useful for studies ofVZV pathogenesi