A PRAGMATIC OVERVIEW TO PREPARE FOR THE COLD SEASON
Bovine Respiratory Syncytial Virus (BRSV) is a single-stranded virus belonging to the Pneumoviridae family1,2. It was renamed Bovine orthopneumovirus in 2016 and Orthopneumovirus bovis in 20221. It is one of the main pathogens involved in Bovine Respiratory Disease (BRD) and causes significant economic losses in the livestock industry.
A SEASONAL DISEASE
BRSV is found worldwide3 and is particularly prevalent in temperate regions. In Europe, between 40% and 80% of cattle (depending on region and population studied) are believed to carry antibodies against BRSV.
Infection can predispose cattle to secondary bacterial infections by organisms such as Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, or Mycoplasma bovis4. The virus is highly contagious and can survive for some time in the environment (cold and humidity).
BRSV mainly circulates in late autumn and winter5, with a marked peak between November and February in most temperate regions (France, Northern Europe, North America).
Why this period?
 | Closed housing Reduced ventilation & accumulation of viral aerosols. |  | Grouped animals Close contact facilitates transmission. |
 | Cold & humidity Increased virus survival in the environment. |  | Thermal stress Decreased immunity.. |
TRANSMISSION AND SYMPTOMS: A CHALLENGE FOR THE LIVESTOCK INDUSTRY
BRSV is transmitted through aerosol droplets, direct contact with an infected animal, or indirectly via contaminated surfaces6,7. Infected animals may shed the virus even before the first symptoms appear.
Clinical signs often occur 7 to 10 days after a stressful event, such as animal transport4.
BRSV affects the respiratory system, particularly the bronchioles and alveoli, causing:
BRSV can lead to very severe forms of disease, particularly in winter, and can cause high mortality in some herds.
DIAGNOSTIC
Several diagnostic methods exist:
 | Rhéa® tests are molecular biology tests that directly detect the pathogen’s DNA/RNA and can therefore be used from the very early stages of infection, even before symptoms are detectable. Their sensitivity is very close to that of PCR, but results are obtained in just 30 minutes. |
 | Vaccination: Of calves and/or cows (to improve colostral immunity). |  | Environmental management: Good ventilation, stress reduction, and careful management of animal mixing. |
| Three main types of vaccines are used against BRSV: Inactivated vaccines (injectable) - Often used in herd vaccination protocols (cows and calves)11. Live attenuated vaccines (intranasal) - Ideal for young calves, but provide shorter immunity than inactivated vaccines12. Combined vaccines (live or inactivated)- Include multiple BRD pathogens such as BHV-1, PI3, or BVDV13. |  | Biosecurity: Quarantine and control of animal introductions. |
1. Walker, P. J. et al. Recent changes to virus taxonomy ratified by the International Committee on Taxonomy of Viruses (2022). Arch. Virol. 167, 2429–2440 (2022).
2. Rima, B. et al. ICTV Virus Taxonomy Profile: Pneumoviridae. J. Gen. Virol. 98, 2912–2913 (2017).
3. da Silva Barcelos, L. et al. Interactions Between Bovine Respiratory Syncytial Virus and Cattle: Aspects of Pathogenesis and Immunity. Viruses 16, 1753 (2024).
4. Sacco, R. E., McGill, J. L., Pillatzki, A. E., Palmer, M. V. & Ackermann, M. R. Respiratory Syncytial Virus Infection in Cattle. Vet. Pathol. 51, 427–436 (2014).
5. Bueno, S. M. et al. Host immunity during RSV pathogenesis. Int. Immunopharmacol. 8, 1320–1329 (2008).
6. Bartz, H. et al. Respiratory syncytial virus decreases the capacity of myeloid dendritic cells to induce interferon-γ in naïve T cells. Immunology 109, 49–57 (2003).
7. Bendelja, K. et al. Decreased Toll-like receptor 8 expression and lower TNF-alpha synthesis in infants with acute RSV infection. Respir. Res. 11, 143 (2010).
8. Jo Mayers and Jason Sawyer. Development and evaluation of a multiplex enzyme-linked immunosorbent assay for the detection of antibodies to bovine respiratory diseases on the Meso Scale Discovery platform. Journal of Veterinary Diagnostic Investigation 24, 4 (2012).
9. Achenbach, J. E. et al. Detection and quantitation of bovine respiratory syncytial virus using real-time quantitative RT-PCR and quantitative competitive RT-PCR assays. J. Virol. Methods 121, 1–6 (2004).
10. Thonur, L. et al. One-step multiplex real time RT-PCR for the detection of bovine respiratory syncytial virus, bovine herpesvirus 1 and bovine parainfluenza virus 3. BMC Vet. Res. 8, 37 (2012).
11. Martinez, D. A., Newcomer, B., Passler, T. & Chamorro, M. F. Efficacy of Bovine Respiratory Syncytial Virus Vaccines to Reduce Morbidity and Mortality in Calves Within Experimental Infection Models: A Systematic Review and Meta-Analysis. Front. Vet. Sci. 9, 906636 (2022).
12. Makoschey, B. & Berge, A. C. Review on bovine respiratory syncytial virus and bovine parainfluenza – usual suspects in bovine respiratory disease – a narrative review. BMC Vet. Res. 17, 261 (2021).
13. Tapiolas, M. et al. Efficacy of a New Multivalent Vaccine for the Control of Bovine Respiratory Disease (BRD) in a Randomized Clinical Trial in Commercial Fattening Units. Vaccines 12, 1233 (2024).
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