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 BRSV before their second year of life. 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 a PCR test is generally the fastest method of diagnosis. The virus can also be isolated from patient material (nasal/throat swabs, lung washes 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 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 completely prevent an animal from becoming infected. WBVR offers a bovine RSV calf model that can be used to evaluate effectiveness of newly developed vaccines for the veterinary field.

Respiratory tract infections in infants

Bovine RSV is genetically highly related to the human RS virus, which is the most important cause of severe lower respiratory tract infections in young children worldwide. Both seasonal infections share many aspects in pathogenesis, clinical manifestations (including age-dependency) and evoked immune responses. In the absence of effective therapeutics for infants there is a persistent unmet need for a licensed RSV vaccine.

Translational calf model for RSV

For development of new vaccines, a representative translational animal model to predict safety and efficacy in the human population is very important. WBVR offers a challenge model in young calves in which a natural history of a bovine RSV infection including obvious clinical respiratory symptoms can be reproduced, which closely resembles the disease in human infants. Together with its abundant sampling options and measurement techniques the assess the course and severity of the respiratory tract infection, the model creates unique possibilities and has demonstrated to be of high additional value in the pre-clinical evaluation of new intervention strategies.

Read more about our calf model

Clinical signs

The onset of illness is typically seen from 5 days post-challenge (dpc) starting with signs of an upper respiratory tract (URT) infection, including runny eyes and nose, and coughing. Following the course of infection, symptoms of the lower respiratory tract (LRT) develop, characterized by an increased breathing rate and/or laboured breathing and commonly accompanied with depression, inappetence and fever (usually peaking between 7 and 9 dpc).

Disease parameters

The WBVR calf model offers unique opportunities to extensively assess the severity of respiratory disease by daily measurements and clinical observations, discriminating for general illness, URT and LRT disease.

• General illness is assessed by a severity score for activity and appetite and a measurement of body weight and rectal temperature.
• Assessment of URT disease includes a severity score for runny nose or eyes and cough.
• LRT disease is assessed by a severity score for effort of breathing, an actual count of the respiratory rate and measurement of oxygen saturation by pulse oximetry.

Evaluate intervention candidates

All disease parameters together provide a representative display of the clinical manifestation, which can be applied as a primary read-out to evaluate promising intervention candidates for their potential on clinical efficacy.

Interested in our infection model?

Are you interested in our translational model to study new intervention strategies? Download the flyer below and feel free to contact our expert:

• 

  drs. MC (Rineke) Klaassen-de Jong

  Veterinary Scientist and Project leader
  Contact form

Flyer: RSV in children and calves