The Molecular Biology of the Morbilliviruses

Abstract

The morbilliviruses are a small, antigenically related genus within the family Paramyxoviridae. They are distinguished from the genus Paramyxovirus by their lack of neuraminidase activity. The group includes an important human virus, measles virus (MV), and three animal viruses, canine distemper virus (CDV), which causes disease in dogs and Mustelidae, rinderpest virus (RPV), causing disease in cattle and other large ruminants, and peste des petits ruminants virus (PPRV), causing disease in sheep, goats, and other small ruminants. Although closely related antigenically, the viruses can be distinguished quite easily by differential neutralization using homologous and heterologous viruses and sera. Their host range is restricted, as indicated above, but they can infect other hosts, although then they do not generally cause disease. Thus, rinderpest viruses cause disease in large ruminants, but cause a subclinical infection in small ruminants. The latter can, however, act as carriers of the disease in some areas of the world and this is of great epidemiological importance. Each virus is antigenically stable, but different strains can be isolated which show widely differing pathogenicity in the host species. In addition to the acute disease, two members of the group, measles and canine distemper viruses, are known to persist and cause chronic neurological disease in a small proportion of infected individuals (see Chapter 12).