Infection of neuronal cell cultures with reovirus mimics in vitro patterns of neurotropism.

Primary neuronal cell cultures of rat fetal cerebral cortex serve as in vitro models for the study of a variety of neuronal membrane receptors. Such studies have focused primarily on receptors for neurotransmitters and drugs. In the present series of experiments, we have employed this model to study the in vitro pattern of infection with reovirus types 1 and 3, two well-characterized neurotropic viruses that show specificity for neurons (type 3) or ependymal cells (type 1) in vivo and whose specificity has been linked with surface receptors on somatic cells. We have found that in primary neural cell culture, reovirus type 3 maintained its specificity by infecting neurons whereas reovirus type 1 did not infect neurons. Both serotypes infected astrocytes in the cultures, type 1 to a greater extent than type 3. In addition, reovirus type 3 bound to the surface of neurons whereas type 1 did not. Using recombinant viral clones, the in vitro tropism and the neuronal binding were shown to be properties of the viral hemagglutinin, a small outer capsid viral protein, as is the case with the neurotropism in vivo. It is postulated that the neurotropism of reovirus type 3 is related to the interaction of the viral hemagglutinin with an as yet undefined structure on the neuronal surface.