Studies on the Persistent Infection with Measles Virus in HeLa Cells

Abstract

HeLa cells were caused to degenerate by infection with the standard measles virus, while those infected with the virus released from the HeLa/MV culture (carried virus) readily established a carrier state. The carried virus had a longer latent period and a lower growth rate in both HeLa and Vero cell cultures as compared with the standard virus. Plaques by the carried virus on Vero cell cultures were delayed in appearance as compared with those by the standard virus. However, when the carried virus was passed once through Vero cells, the virus became able to form plaques as readily as the standard virus. Also the passed virus was found to have lost the ability to establish a carrier state. These results may suggest the possibility of a host-controlled variation, though the mechanism of establishment of the HeLa/MV culture which harbors such a variant remains obscure.

Studies on a measles virus variant inducing persistent infections in cultured cells

“…It was known beforehand that monkey kidney cells allow plaque formations by some attenuated and slowly developing measles virus strains (7,16,26,29) and that incubation temperatures can considerably affect virus multiplication, especially of the UP variant (4). Two monkey kidney cell lines (37 RC and Vero) were employed, in parallel with HeLa cells, at different temperatures (33 °, 35 °, 37 ° and 39 ° C), for plaquing of two UP and DP preparations both diluted to contain about 100 TCIDs0 in the volume of inoeulum.…”

“…It has been known that measles virus has a capacity to establish persistent infections in different "in vitro" cell cultures (2,14,15,18,27,32). Generally a carrier state becomes stable after several initial passages during which the virus infection induces extensive cytopathic effects (CPE) and just a few of the infected cells survive and continue to multiply (i5, 18,27,32).…”

“…In some cases special cultural conditions are also needed to establish the persistent infection (14,18). A more ready induction of the carrier state is described only by the virus released from carrier cultures (16,32).…”