ÉTUDE D'UNE LIGNÉE DE CELLULES KB INFECTÉES CHRONIQUEMENT PAR LE VIRUS PARA-INFLUENZAE TYPE 3 : I. ASPECTS DE LA PRODUCTION VIRALE

Abstract

A strain of cells chronically infected with type 3 para-influenzae virus was obtained. The proportion of virus-producing ceils in this carrier system, called KB.EA, was measured by two different technics. Only a fraction of KB.EA cells, varying from one experiment to the other, was found to produce the virus. Virus production did not seem to take place simultaneously in all the cells, which apparently yielded the virus at varying times, and occasionally only after 10 days of incubation.The titer of total virus yielded by cultures of KB.EA cells incubated at 37 °C and 41 °C was determined at fixed intervals over a period of 4 days.The titer showed marked variations during the course of both types of cultures. The amount of total virus harvested at 41 °C was about a tenth of that obtained from the culture incubated at 37 °C. No "hot-mutant" could be detected after 4 days of incubation at 41 °C.The addition of a potent antiserum in the culture medium did not sterilize the KB.EA strain although the same serum inhibited the plaque formation induced by type 3 para-influenzae virus on normal KB cells.From the results obtained, several hypotheses meant to explain the cell resistance and the persistence of virus in cultures of KB.EA cells are discussed.