Morbillivirus Receptors and Tropism: Multiple Pathways for Infection

Sato, Hiroki; Yoneda, Misako; Honda, Tomoyuki; Kai, Chieko

Although Vero cells had been used for MeV isolation for a long time, the isolation was not highly efficient and usually required several blind passages. In contrast, Kobune et al. found that an Epstein-Barr-virus-transformed marmoset B-cell line, B95a, is 10,000-fold more sensitive to the MeV present in clinical specimens than Vero cells. Furthermore, MeVs isolated and propagated in B95a cells cause clinical signs in experimentally infected monkeys, which resemble those of human measles such as rashes and Koplik's spots, leukopenia, and marked histological lesions in the lymphoid tissues (Kobune et al., 1990) . Subsequently, Kobune et al. (1990 Kobune et al. ( , 1996 reported that two strains of wild MeV from the same patient, one isolated in B95a cells and the other in Vero cells, had different virulence in monkeys. The former induced acute signs of MeV infection, whereas the latter did not induce any clinical signs of disease and caused milder histological lesions. These findings strongly indicated that MeV isolated in B95a cells maintains virulence similar to that in humans and that isolation in Vero cells leads to loss of virulence.