Bovine respiratory syncytial virus infection: clinical manifestations, pathogenesis and molecular epidemiology (review)

Introduction. Bovine respiratory syncytial infection is widespread in all countries of the world, including the Russian Federation. The etiologic agent is Orthopneumovirus bovis , it belongs to the family Pneumoviridae , genus Orthopneumovirus . Cattle are the main reservoir of the virus. Objective. This literature review aims to summarize and give analysis of the published data on clinical manifestations, pathogenesis and molecular epidemiology of the causative agent of bovine respiratory syncytial infection. Materials and methods. The study is based on publications from the most authoritative domestic (eLIBRARY.RU) and foreign (Web of Science, Scopus, PubMed) sources, as well as the results of our own studies published in the literature. Results. Animals of all ages are susceptible to the disease, the infection is most severe in calves under 6 months of age. The incidence of the herd is on average 60–80%. The nature of the infection varies from asymptomatic and mild to severe lower respiratory tract disease, including emphysema, pulmonary edema, interstitial pneumonia and bronchopneumonia, while the mortality rate among calves can reach 20%, and in adult animals the subclinical form is more often recorded. The virus has a powerful immunomodulatory effect. Severe damage to the respiratory tract is mediated mainly by hyperactivity of the immune response, and not by the replication of the virus itself. The virus increases the susceptibility of calves to secondary infections and promotes colonization of the lower respiratory tract by bacteria. Currently, ten genetic subgroups of the virus (I–X) have been identified using phylogenetic analysis of the nucleotide sequences of the G and N genes, between which there is a geographical correlation. In regions such as the Urals, Siberia, and the Republic of Kazakhstan, isolates of the virus of genetic subgroups II and III circulate among cattle. Conclusion. The review presents current data on the etiology, pathogenesis features and clinical manifestations of bovine respiratory syncytial infection, as well as the genetic diversity of the pathogen in the world, in the Russian Federation and the Republic of Kazakhstan.