Molluscum contagiosum: characterization of viral DNA and clinical features

Abstract

SUMMARYRestriction endonuclease analysis of molluscum contagiosum virus DNA revealed two subtypes. In a study of 46 isolates from 41 patients, some with no other disorder and some with atopic dermatitis, the ratio of MCV I isolates to MCV II was 34:12. Multiple clustered lesions removed at the same time from an individual patient yielded only one type of MCV. Lesions induced by MCV I or MCV II were indistinguishable on the basis of size and form. Neither subtype was associated exclusively with lesions at certain sites or with other clinical features. Heterogeneity of DNA restriction endonuclease cleavage patterns amongst isolates of the same subtype was observed, this being greatest for MCV II.Molluscum contagiosum, a benign skin tumour of man resulting from a common poxvirus infection, has not previously been investigated intensively because of the inability to culture the virus in vitro and the fact that ordinarily the papules resolve spontaneously. Transmission of the virus is mechanical, and lesions may be found anywhere on the skin but are usually clustered. A common site of infection in adults is the genital area and, in such cases, sexual transmission of the virus is likely. Numerous, widespread, persistent and disfiguring lesions may develop in the immunosuppressed (for example in Hodgkin's disease or AIDS) and in atopic dermatitis, where immune defects have been suggested as a possible explanation for the increased incidence of molluscum contagiosum and other cutaneous infections (Postlethwaite, 1970;Brown, Nalley & Kraus, 1981). Restriction endonuclease analysis of MCV DNA has revealed two viral subtypes (Darai et al. 1986). We have reported the further characterization and physical mapping of their genomes, which are essentially collinear, and shown that MCV DNA is similar to Orthopoxvirus DNA with respect to size, terminal cross-linking and the presence of inverted terminal repetitions (Porter & Archard, 1987).In the study described here we have characterized viral DNA from 46 independent isolates from 41 individuals presenting to the skin or genito-urinary clinics to see whether there is any correlation between MCV type and clinical features or the distribution of the lesions. When several lesions were clustered at the same site and might reasonably be assumed to have arisen from the same infection, lesions were pooled. Patients with or at risk of human immunodeficiency

Molecular epidemiology of Australian isolates of molluscum contagiosum

“…More recently, further restriction endonuclease analyses on MCV DNA isolates have established that the virus exists as two major types, designated MCV 1 and MCV 2. Within these two groups further variants, termed MCV l v and MCV 2v, have been identified on the basis of minor differences in their DNA cleavage patterns due to the loss of BamHI recognition sites [Darai et al, 1986;Porter et al, 1987;Scholz et al, 19881. Several surveys on the molecular epidemiology of MCV infection have been published in the last 5 years.…”

Characterisation by restriction mapping of three subtypes of Molluscum contagiosum virus

“…The ability of the terminal restriction fragments of poxviral DNA to renature rapidly following denaturation, since they are covalently cross-linked [Geshelin and Berns, 19741, confirmed this identification for MCV I [Porter and Archard, 19871 and I1 DNA (data not shown). Visualisation by electron microscopy of the continuous DNA strand after denaturation of the termini has been reported for MCV DNA [Parr et al, 19771.…”

“…As discussed above, preliminary maps for MCV I11 DNA were previously published erroneously as those for MCV I1 [Porter and Archard, 19871. …”

“…They described three subtypes: I, 11, and 111, the last two being very similar and probably variants of the same subtype. Darai et al [1986] similarly used BamHI to distinguish two MCV subtypes but used different nomenclature: I and 11, corresponding to subtypes II/III and I, respectively, of Parr et al We have also previously demonstrated the same two MCV subtypes, adopting the nomenclature used by Darai et al, and published restriction maps of the genomes of a single isolate of each for the enzymes BamHI, ClaI and Hind111 [Porter and Archard, 19871. MCV DNA is similar to orthopox- virus DNA with respect to size (180-200 kb), terminal cross-linking, and the presence of an inverted terminal repeat, but shows no cross-hybridisation with vaccinia DNA.…”

“…MCV DNA is similar to orthopox- virus DNA with respect to size (180-200 kb), terminal cross-linking, and the presence of an inverted terminal repeat, but shows no cross-hybridisation with vaccinia DNA. The presence of tandem repetitions within the terminal repeats has been inferred from the observed size variations of the terminal fragments between independent isolates [Porter et al, 19871.…”