CHARACTERIZATION OF A NOVEL SYNCYTIUM-INDUCING BABOON REOVIRUS

A syncytium-inducing reovirus was recently isolated from brain homogen ates of a baboon suffering from acute, progressive meningoencephalo my elitis. This baboon reovirus (BRV) was classified as a member of the g enus Orthoreovirus, family Reoviridae, on the basis of the characteris tic capsid morphology and genome and protein profiles. We have assesse d the relationship between BRV and the other syncytium-inducing reovir uses in order to determine whether the emergence of this virus represe nts a host range or pathogenic alteration in a previously described is olate or the appearance of a novel entity. BRV was compared to represe ntative members of the prototype mammalian reoviruses, avian reoviruse s, and Nelson Bay virus on the basis of electropherotype, protein prof ile, and antigenic similarity as measured by immunoprecipitation using homologous and heterologous antisera. In spite of similarities betwee n the genome and protein profiles of BRV and the other orthoreoviruses , migration-rate polymorphisms indicate that BRV has diverged extensiv ely from the previously described syncytium-inducing orthoreoviruses. Most importantly, the limited epitope conservation suggests that BRV h as existed in genetic isolation from other reoviruses for quite some t ime. We conclude that BRV represents a novel syncytium-inducing mammal ian reovirus, which is of particular interest in view of its associati on with disease in nonhuman primates during natural infections and its unusual syncytial phenotype. (C) 1995 Academic Press, Inc.