BACKGROUND: Molluscum contagiosum virus (MCV) causes molluscum contagiosum (MC) 
in both children and adults. Recent studies have revealed that the DNA of MCV 
can be classified into two major types by restriction enzyme cleavage patterns; 
however, the relationship between MCV types and the clinical features has not 
been fully understood. Our study was conducted to examine whether there are 
geographic differences in the incidence of MCV types and whether a correlation 
exists between MCV types and the age, sex, and clinical status of the patients.
METHODS: Specimens were obtained from 171 Japanese patients. The total DNA was 
extracted and digested with the restriction enzymes, BamH I, Hind III, and Cla 
I, respectively. Specimens were then electrophoresed in agarose gels. The gels 
were stained with ethidium bromide and photographs were taken under 
transillumination.
RESULTS: Six different cleavage patterns were observed; they were classified 
into two major types, MCV 1 and MCV 2, consisting of two MCV 1-variants, and MCV 
2 prototype, and three MCV 2-variants. The ratio of MCV 1 to MCV 2 was 13:1. MCV 
1 was commonly detected in children (98%) and adult women (92%). MCV 2 was more 
frequently isolated from adult men (44%) and from patients with human 
immunodeficiency virus (HIV) infection (75%).
CONCLUSION: MCV types found in Japanese children and adult women were 
predominantly MCV 1 and less frequently MCV 2. This pattern is similar to that 
observed in European countries and Australia, suggesting a high frequency and 
world-wide distribution of MCV 1. The higher incidence of MCV 2 among adult men 
and HIV-positive patients may indicate that transmission routes of MCV 1 and MCV 
2 is somewhat different, of which the latter may be in part by sexual contact.