Wageningen Bioveterinary Research (WBVR) conducts extensive research into the immunopathology of Bovine Respiratory Syncytial Virus (BRSV).
What is BRSV?
This virus is an important pathogen in cattle. It causes cold-like symptoms in adult animals, while in calves it infects the small airways, causing bronchiolitis or pneumonia. The virus causes outbreaks of this respiratory disease annually, particularly in calves up to the age of six months.
How does the virus spread?
Almost all cattle will have been infected with SCSV before their second year. Infections and re-infections mainly occur in the autumn and winter. Spreading of the virus is rarely seen at other times of the year, and the virus seems to survive in a dormant form within the population.
What are the symptoms?
BRSV can be particularly severe in young animals, where it often causes fever (body temperature above 39.5ºC), rapid breathing, breathing difficulties and abdominal breathing. The clinical symptoms usually start with coughing and nasal discharge. If the small airways are also affected, expiratory wheezing, rapid breathing and signs of shortness of breath, as well as cyanosis and forced breathing (active involvement of the rib and abdominal muscles on inhalation) are observed. Clinical symptoms coinciding with bronchiolitis and/or pneumonia are serious and are very likely to be fatal.
How do you control BRSV?
To control and prevent the disease, it is necessary to understand how the body ultimately protects itself against the virus. It is therefore important to know what the consequences of the infection are for the body and how the body's immune system reacts. After a natural infection or after vaccination, for example, virus-specific antibodies are produced as part of the specific immune system. An effective immune response means that the animal is protected against a potential (re)infection, but in some cases a non-effective immune response can also be induced. Plenty of cases are known in which, for example, infected vaccinated calves showed much more severe symptoms than unvaccinated ones. WBVR is conducting extensive research into the role of the immune system during the course of the clinical infection.
How does WBVR detect the virus?
Direct detection of virus in secretions from the airways using immunofluorescence or with the aid of a PCR test is generally the fastest method of diagnosis. The virus can also be isolated from patient material (nasal/throat swabs, lung flushes or lung tissue from autopsy). The patient material is then transferred to virus-sensitive cells, on which a characteristic abnormal effect can be observed after a few days to a week. Specific antibodies produced to combat the virus can be detected with an ELISA or virus neutralisation test (VNT).
Is there a vaccine available?
Different types of vaccines are available: live/attenuated or inactivated virus vaccines, vaccines with one or more components and possible combinations (multiple components, live/attenuated and inactivated), all with vaccine-specific advantages and disadvantages. None of the current vaccines seems to be able to prevent an animal from becoming infected.