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In vitro interference between low and high leukaemogenic variants of rauscher virus
Author(s) -
Boyd Rosemary E.,
Youn Jung Koo,
Barski Georges
Publication year - 1973
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910110126
Subject(s) - virus , in vitro , biology , viral interference , virology , superinfection , immunofluorescence , inoculation , immunology , antibody , viral replication , biochemistry
Cultures of the virus‐free P4bis line, originating from a C57B1 mouse, were infected in vitro with a “low leukaemogenic” variant (RC) of the Rauscher leukaemia virus (RV), prepared from long‐term cultures of this virus in syngeneic cells. Later, after different delays, these infected cultures (P4bis + RC) were superinfected with a highly pathogenic variant (RR) of the RV, obtained from short‐term cultures of RV extracted from spleens of leukaemic mice. Eighteen days after these superinfections with RR, supernatants of the doubly‐infected cell cultures (P4bis+RC+RR) and their corresponding controls were assayed for leukaemogenic potential by intraperitoneal inoculation into young adult BALB/c mice. The proportion of mice which had developed leukaemia by the 120th day after inoculation served for the evaluation of in vitro interference between the RC and RR virus variants. Even when the in vitro infection of cells with RC virus was followed only 1 h later by the RR superinfection, there was a significant difference between the proportion of leukaemic animals in the group inoculated with P4bis+RC+RR supernatant (56%) and that in the P4bis+RR positive control group (88%). With intervals of 12 days or 21 days between the two in vitro viral infections, the drop in leukaemogenicity of the doubly‐infected cultures became more accentuated; the longer the time interval, the greater was the interference effect. Indirect immunofluorescence tests made at intervals after infection of P4bis with RC showed a steady increase in the percentage of RV antigen positive cells up to the 3rd week after infection. The mechanism of the observed interference is discussed, and it is suggested that a straight relationship exists between the spread, horizontal and/or vertical, of the RC virus infection in the cultures and the blocking of their superinfection by the highly pathogenic RR virus.