Investigation of varicella-zoster virus infection by polymerase chain reaction in the immunocompetent host with acute varicella.

A polymerase chain reaction (PCR) method developed to detect varicella zoster virus (VZV) in clinical samples is based on amplifying sequences of viral gene 31, the coding region for glycoprotein II. Its sensitivity was evaluated by amplification from plasmid VZV DNA containing VZV gene 31; 45 copies were detected in 1 microgram of human DNA. In testing within 24 h after the onset of varicella exanthem, 21 (75%) of 28 lesion samples were positive by VZV PCR, whereas VZV was isolated from only 21% by a standard tissue culture method. Only 1 (3.3%) of 30 samples of oropharyngeal secretions but peripheral blood mononuclear cells from 8 (67%) of 12 patients were positive. The sensitivity and specificity of the VZV PCR method indicates its usefulness for investigating the pathogenesis of VZV infection. Direct contact with cutaneous lesions rather than respiratory secretions may be the most important route of VZV transmission from healthy individuals with acute varicella.