Molluscum contagiosum lesions obtained from 75 Australian patients, 22 (29%) of whom were HIV positive, were examined by restriction endonuclease analysis and Southern blot hybridisation using radiolabelled and digoxigenin-labelled MCV DNA probes. The isolates were classified (MCV 1, 1v, 2, and 2v) on the basis of these results, which were in turn correlated with the clinical features of each lesion. A total of 44 (59%) of the lesions contained MCV 1 or 1v, 24 (32%) contained MCV 2 or 2v, three (4%) contained multiple MCV types, whereas four (5%) of lesions submitted contained no detectable MCV DNA. The ratio of MCV 1/1v to MCV 2/2v was determined to be approximately 1.75:1. There were substantial differences between the distribution of MCV types 1 and 2 among patients of different age groups, but no significant relationship between MCV type and the sex of the patient was found. MCV 2 was more frequently detected in lesions from anogenital areas and in immunosuppressed (HIV-positive) patients, and MCV 1 was more commonly isolated from skin rather than genital lesions, but neither association was statistically significant. Fragment F (10 kbp) obtained from the genome of MCV 1 was capable of differentiating MCV 1 from MCV 2 when used as a probe in hybridisation experiments with BamHI cut samples and may be useful when small amounts of lesion prevents differentiation by direct visualisation of restriction endonuclease fragments.

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