Review on Bovine Respiratory Syncytial Virus Characteristic, Pathogenesis and Control Methods Applied for the Disease

Abstract

Bovine Respiratory Syncytial Virus (BRSV) is an envelope, non-segmented, negative-stranded RNA virus belonging to the Pneumovirus genus within the subfamily Pneumovirinae, family Paramyxoviridae. The virus virion consists of a lipid envelope, derived from the host plasma membrane, containing three virally encoded trans-membrane surface glycoproteins, which are organized separately into spikes on the surface of the virion. The virus causes disease in cattle, sheep, goats and camelids where cattle are supposed to be a natural host and all other animal species listed may play as an epidemiological role in certain circumstances. Human Respiratory Syncytial Virus (HRSV) is also an important respiratory pathogen in infants and young children. The distribution of BRSV is worldwide and the virus has been isolated from cattle in Europe, America and Asia. The virus causes regular winter outbreaks of respiratory disease in cattle and a sero prevalence of 30–70% has been detected in this species. BRSV is one of the main causes of severe pneumonia, interstitial edema, and emphysema in cattle which spreads by infected animal aerosols, direct contact and transmission through objects (fomites). It can vary in its ability to cause disease, ranging from fatal to no clinical signs shown. BRSV can also make the animal more vulnerable to secondary infections, where the virus weakens the immune system so that bacteria that are usually harmless can cause disease. BRSV replicates primarily in the superficial layer of the respiratory ciliated epithelium and replication can also be detected in type II pneumocytes. Various types of proteins of this virus can contribute for its pathogenicity. Since the peak incidence of severe BRSV disease is between 2 and 6 months, an effective BRSV vaccine must be capable of stimulating an effective immune response within the first months of life. However, the presence of maternallyderived antibodies poses a major obstacle and deletion of non-essential genes represents an attractive option for production of a live, attenuated virus vaccine.