9 Cellular Receptors for Alphaviruses

Abstract

Receptors on host cells that are used by viruses to enter cells and initiate infection have received a great deal of attention of late because of their obvious importance in determining in large part the host range, tissue tropism, and virulence of a virus. The alphaviruses represent an interesting and special situation. The members of this group have an enormous host range that comprises both invertebrate hosts and vertebrate hosts (Chamberlain 1980; Griffin 1986; Niklasson 1988; Peters and Dalrymple 1990). All alphaviruses are transmitted by arthropod vectors, in which the virus replicates. Mosquitoes are used as vectors by most alphaviruses, but Fort Morgan and Bijou Bridge viruses are vectored by swallow bugs, and several alphaviruses, including Sindbis virus (SIN) (Shah et al. 1960) and eastern equine encephalitis virus (EEE) (Scott and Weaver 1989), have been isolated from mites and other hematophagous arthropods as well as from mosquitoes. In the case of EEE, the major vector is the mosquito Culiseta melanura, but other mosquitoes can also transmit the virus and naturally infected chicken mites have been shown to be able to transmit the virus, albeit inefficiently. During the process of mosquito transmission, the virus must productively infect several tissues within the mosquito. The virus is ingested when the insect feeds on a viremic host and first infects cells of the midgut; later the infection must spread to the salivary glands in order for the mosquito to transmit the virus when it next feeds on a vertebrate. A wide variety of vertebrates,...