Bovine respiratory syncytial virus

Bovine respiratory syncytial virus (BRSV) is pneumovirus closely related to human respiratory syncytial virus (RSV) that is a common cause of respiratory disease in cattle, particularly calves. It is a negative-sense, single-stranded RNA virus that replicates in the cytoplasm of the cell.^[1] Similarly to other single-stranded RNA viruses, the genome of BRSV has a high mutation rate, which results in great antigenetic variation. Thus, BRSV can be split into four different subgroups based on antigen expression (A, B, AB, and intermediate).^[2]

Bovine respiratory syncytial virus
Virus classification
(unranked):	Virus
Realm:	Riboviria
Kingdom:	Orthornavirae
Phylum:	Negarnaviricota
Class:	Monjiviricetes
Order:	Mononegavirales
Family:	Pneumoviridae
Genus:	Orthopneumovirus
Species:	Orthopneumovirus bovis

BRSV diagram

Causes

In around 90% of cases, infection with BRSV results in secondary bacterial pneumonia due to interference with the host's immune system and enhancement of bacterial adherence and colonisation by the virus.^[1] Pasteurella multocida, a common commensal of the nasopharynx of cattle, appears to be the main bacterial agent in BRSV-related bovine respiratory disease (BRD).^[3]

Treatment

Similarly to other viral infections, treatment of BRSV is typically supportive. Anti-inflammatory drugs may be required to reduce fever and inflammation, which may increase the affected animal's food and water intake. Non-steroidal anti-inflammatory drugs (NSAIDs) are preferred to corticosteroids due to the latter's immunosuppressive effects. In the case of a secondary bacterial infection, antimicrobials may be given.^[2] While commercial BRSV vaccines are available, appropriate biosecurity measures and animal husbandry may be sufficient to prevent spread of disease.^[4]