Host range of small-ruminant lentivirus cytopathic variants determined with a selectable caprine arthritis-encephalitis virus pseudotype system

The small-ruminant lentiviruses ovine maedi-visna virus (MVV) and caprine a rthritis-encephalitis virus (CAEV) cause encephalitis, progressive pneumoni a, arthritis, and mastitis in sheep and goats. Icelandic MW strains, which are lytic in tissue culture, have a wide species distribution of functional receptors, which includes human cells. In contrast, functional receptors f or the nonlytic CAEV CO are absent from human cells. To determine if the wi de species distribution of functional receptors is a common property of NVV strains or related to cytopathic phenotype, we tested the infectivity of v iruses pseudotyped with the envelope glycoproteins of MW K1514, CAEV CO, an d lytic and nonlytic North American MVV strains to cells of different speci es. Replication- defective CAEV proviral constructs lacking the env, tat, a nd vif genes and carrying the neomycin phosphotransferase gene in the vif-t at region were developed for the infectivity assays. Cotransfection of huma n 293T cells with these proviral constructs and plasmids expressing CAEV, M W, or vesicular stomatitis virus envelope glycoproteins produced infectious pseudotyped virus which induced resistance of infected cells to G418. Usin g these pseudotypes, we confirmed the wide species distribution of Icelandi c MVV receptors and the narrow host range of CAEV. However, functional rece ptors for the two North American MVV strains tested, unlike the Icelandic M VV and similar to CAEV, were limited to cells of ruminant species, regardle ss of cytopathic phenotype. The results indicate a differential receptor re cognition by MVV strains which is unrelated to cytopathic phenotype.