uMMARY DNA synthesis in molluscum contagiosum nodules was investigated by autoradiography using 'H-thymidine. Scratch preparations of molluscum nodule stained with Giemsa showed that many cells contained reddish purple cyto-PIasmic inclusions. These inclusions were classified according to their size and characteristics into stages I, U and 111. The inclusions in stages I and U 11ad the same staining characteristics as " B " type inclusions of poxviruses. Inclusions in stage 11 appeared to be

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... dually transformed into stage 111 inclusions, whicli had a lobular structure and corresponded to the so-called molluscum bodies of Lipshiitz The sites of cytoplasmic DNA synthesis corresponded exclusively with these incluit was found by quantitative autoradiography that cells bearing inclusions did not show active nuclear DNA synthesis. Many cells with well-developed inclusions appeared to be degenerating. This suggests that virus-producing cells do not multiply but degenerate. Autoradiography of sections of the molluscum nodulc showed that active nuclear DNA synthesis occurred only in the inclusion free-basal cells of the epidermis surrounding the molluscum foci. The host-virus interactions in molluscum contagiosum are similar to those in poxgroup viruses