Serial passage of murine K-papovavirus in primary cultures of mouse embryo cells. Brief report.

Murine K-papovavirus was serially passaged 10 times in primary cultures of mouse embryo cells, using cell suspensions and media from infected cultures to inoculate fresh flasks at each passage level. Titers of K virus infectivity in cell suspensions and media rose during serial passage, but viral hemagglutinating activity was not detected in cells or media before the 10th passage. Although the infectivity of K virus for mouse embryo cultures was enhanced by serial passage, lethality of the virus for suckling mice was lost. The present study represents the first successful serial transmission of K virus infection in vitro.