Analysis of molluscum contagiosum virus genomes isolated in Japan

The genomes of 477 Japanese strains of molluscum contagiosum virus (MCV) were analyzed using an in‐gel digestion method with the restriction enzyme BamHI, and classified into four types, including a newly detected type (MCV type 4). All type 1 (MCV‐1) genomes examined so far in Japan showed a common difference from the genome of the MCV‐1 prototype (MCV‐l p), the type reported to be most prevalent in Europe. The common markers of the variants of MCV‐1 were 24‐kbp fusion fragments generated by the loss of a BamHl site between the D2 and F fragments of MCV‐1 p. These variants of MCV‐1 were classified into three groups (MCV‐lva, MCV‐1vb, MCV‐l vc), with the variability among them being due to additions and losses of BamHl sites located in the right terminus and around the Eand I fragments of MCV‐lva. The restriction map of MCVB was generated and lined up with those of the other types. Cross‐hybridization analysis revealed that the organization of all types of MCV genomes were essentially colinear. Considerable numbers of BamHl restriction sites were conserved between MCV‐2 and 4, indicating a close analogy between them. The overall prevalence of MCV, as shown by the ratios of MCV‐1 (MCV‐1p):MCV‐2:MCV‐3:MCV‐4, was 436(0):13: 24:4. Thus, the molecular epidemiology of MCV in Japan is characterized by the absence of the European prototype of MCV‐1, the exclusive occurrence and abundance of variants of MCV‐1, a greater prevalence of MCV‐3 over MCV‐2, and the presence of MCV‐4. © 1995 Wiley‐Liss, Inc.