Isolation of varicella-zoster virus from vesicles in children with varicella

Varicella-zoster virus (VZV) was isolated from 29 samples of the vesicular fluid in 13 otherwise healthy children with varicella who were aged from 7 months to 7 years. Human embryonic lung cells were used for viral isolation, and VZV was identified by a characteristic cytopathic effect and an indirect immunofluorescence assay. VZV was found in 17 samples; in two (12%) of which it was also detected after filtration (0.45 microns). The rate of isolation was 100% in the first two days after the onset of the disease. It declined gradually with time to 1 of 6 in the samples 6 days after the clinical onset. Specific IgG antibody to VZV was investigated in the same materials. The positive rate was 0% (0/13) in the first 3 days and increased to 7 of 16 in the following 3 days after the onset. VZV was not isolated from samples with specific antibody. In conclusion, VZV can be isolated easily from vesicles within the first 3 days of onset, but the filtration of samples affects its isolation. Infective VZV disappears gradually in vesicles after the first 3 days, and this may be related to the establishment of immune reactions including specific antibody.