Bovine Respiratory Syncytial Virus

Abstract

Bovine respiratory syncytial virus (bRSV) is the main cause of respiratory disease in beef and dairy cattle worldwide. It is responsible for substantial economic losses to the livestock industry because of morbidity, mortality, treatment and prevention costs. Several studies have demonstrated that the frequency of bRSV infection is correlated with the density of the cattle population and the age of the animals. The virus has been isolated in a number of countries, including in Europe, America and Asia. Seroprevalence studies have also shown that bRSV is widely distributed in many countries, indicating that viral transmission is common among herds, regardless of the geographical location. Limited information is available about molecular epidemiology of the virus. DNA sequencing and phylogenetic analysis have hugely contributed to defining bRSV genotypes, evolution, spread and transmission; however, future studies analysing the same genes and longer sequences of bRSV should be performed in order to provide more accurate information about circulating strains. bRSV outbreaks often occur during winter but they also have been reported during summer. Animals can be infected with the same strain several times through life, and for that reason, it is important to update epidemiology studies in order to design more effective control strategies. There are a number of vaccines available for bRSV, but their efficacy is controversial. An ideal vaccine should be efficacious in the presence of maternal antibodies and should be able to induce a long-lasting protective immune response. Although significant progress has been made with regards to prevention of infection, additional investigations are needed to better identify prophylactic and therapeutic measures.