Abstract
The defective genome of murine sarcoma virus (MSV)* (MOLONEY isolate) may be rescued from non-producer hamster tumour cells (HT-1) by co-cultivation of the latter and mouse embryo cells with added helper murine leukaemia viruses (MuLV) (Huebner et al. 1966; Huebner, 1967). Rescue of MSV from HT-1 cells by co-cultivation with MuLV-carrier cells has not, however, been described. This report describes the retrieval of MSV from mixed cultures of HT-1 and various MuLV-carrier cells of mouse and hamster origin. Moreover, it was found that the frequency of success and titres of MSV recovered by co-cultivation of HT-1 and F4, one of the MuLV-carrier mouse cell lines, were much higher than those obtained by the conventional method. We have analysed the factors responsible for such high efficiency of genome rescue.
Among the MuLV-carrier cell lines used, F4 and F5 were derived from two of nine Rauscher pseudotype MSV (MSV(RLV) transformed foci of NIH Swiss mouse embryo cells isolated by trypsinization within a cloning ring.
* Since MOLONEY strain murine sarcoma virus is the subject of the present study, the abbreviation MSV will be used in this article to denote this virus unless otherwise specified.