Pneumovirus-like characteristics of the mRNA and proteins of turkey rhinotracheitis virus

Abstract

Electronmicroscopy has indicated that turkey rhinotracheitis virus (TRTV), the causative agent of an acute repiratory disease in turkeys, is a member of the Paramyxoviridae family. To determine if TRTV belongs to one of the three defined genera of this family ( Paramyxovirus, Morbillivirus and Pneumovirus) we have analysed the RNA and proteins induced during replication of TRTV in Vero cells. Following replication in the presence of actinomycin D 10 polyadenylated RNA bands, ranging in M r from 0.22 to 2.0 × 10 6, were detected in infected cells; some bands probably contained 2 or more RNA species. Viral proteins were studied after radiolabelling in the presence of [ 35S]methionine and [ 3H]glucosamine. Comparison of the polypeptides in mock-infected and infected cells, virions and nucleocapsids and after lentil-lectin chromatography and immunoprecipitation revealed seven virus-specific polypeptides (p), some of which were glycosylated (gp): gp82 ( M r 82K), gp68, gp53, gp15, p43, p40 and p35. These are considered to be analogous to the large glycopolypeptide (HN, H and G), fusion protein precursor F0, the F protein cleavage products F1 and F2, nucleocapsid (N), phosphorylated (P) and matrix (M) polypeptides, respectively, of the Paramyxoviridae. Two other polypeptides ( M r 200K and 22K) were also detected, as was a glycopolypeptide of M r 97K, probably related to gp82. Tunicamycin inhibited glycosylation of gp53 and gp15 but gp82 was little affected, most glycans still being present on a glycopolypeptide of approximately 79K. This finding, indicating that gp82 has mostly O-linked glycans, considered with the mRNA profile and the molecular weight of the N protein shows that of the three genera in this family, TRTV most closely resembles the Pneumovirus genus.