Adaptation of Equine Abortion Virus to Earle's L Cells in Serum-Free Medium with Plaque Formation. ∗

Discussion and summary

This report is an account of the adaptation of EAV to L-M 929 cells with identification by complement-fixation methods. Infected cultures show cytopathic effects which may be measured by both TCID₅₀ or plaque-counting methods. The failure of the virus to propagate in L cells (original) in early experiments is unexplained. During this period the cells were grown in horse and human sera which may have been inhibitory. The possibility that the L-M 929 strains could be directly infected by hamster-propagated EAV has not been excluded. The possibility of contamination of the L-cell strain used in this study with HeLa cells has been considered. The special chromosomal marker of the L-M 929 strain permits precise identification and has not changed, according to Hsu and Merchant(6). Furthermore, YELP has proven very toxic to the HeLa cell line, and cell growth is highly unlikely in this medium.