Study Examines Swine Viruses and Their Impact on Pig Health

By Blake Jackson

A new study funded by the Swine Health Information Center (SHIC) has investigated the presence and potential health impact of mammalian orthoreovirus (MRV) and porcine adenovirus (PAdV) in US swine herds.

Led by Dr. Wenjun Ma at the University of Missouri, the research found that both viruses can infect pigs and may contribute to general enteric disease, but they were not linked to severe or unusual clinical symptoms.

The study aimed to better understand how frequently MRV and PAdV occur in US pig populations and evaluate their ability to cause disease and spread among animals.

Researchers noted that limited information was previously available regarding the prevalence, epidemiology, and production impact of these viruses in US swine herds.

Scientists analyzed hundreds of samples collected through diagnostic laboratories, including lung, intestinal, blood, and fecal samples from pigs across multiple states. Testing showed that MRV was detected in a small percentage of lung and intestinal tissue samples, while antibody testing indicated that previous exposure to MRV was common among sampled pigs.

Researchers also examined PAdV through PCR testing of swine samples. While some positive results were identified in fecal and lung samples, infectious virus was not successfully recovered, suggesting limited evidence of active PAdV infection in the tested populations.

Controlled studies using young weaned pigs were also conducted to evaluate whether MRV and PAdV could cause disease individually or together.

The infected pigs developed mild symptoms, including diarrhea and fever, and viral genetic material was detected in intestinal tissues. However, co-infection did not result in more severe disease compared with individual infections.

The findings indicate that MRV and PAdV are present in US swine populations and can affect the intestinal and respiratory systems of pigs. However, the viruses appear to play a limited role in severe disease under the conditions studied.

For producers and veterinarians, the research provides valuable information for interpreting diagnostic results and making herd health decisions.

Continued monitoring and surveillance will remain important to determine how these viruses interact with other pathogens, management challenges, or environmental stressors that may influence swine health and production outcomes.

Photo Credit: gettyimages-seastock