Is Porcine Astrovirus 4 an Emerging Cause of Respiratory Disease?
Previous studies have shown evidence of porcine astrovirus 4 (PoAstV4) in respiratory tract lesions of pigs, but the direct contribution of PoAstV4 to clinical disease is poorly understood. That's why a new study is seeking to understand if PoAstV4 is a primary cause of respiratory disease.
Led by Mike Rahe of North Carolina State University, this study funded by the Swine Health Information Center (SHIC), is studying the pathogenesis of PoAstV4 infection in weaned pigs under experimental conditions. In December 2023, researchers began characterizing the course of infection over time and providing a foundation for rapid and accurate identification of respiratory illness in pigs.
In a 2022 SHIC-funded study, a retrospective analysis of porcine respiratory disease cases submitted to the Iowa State University VDL from Jan. 1, 2019, to Aug. 1, 2022, was conducted to evaluate the presence of PoAstV4 within microscopic lesions consistent with viral infection of airways, SHIC explained in a release. PoAstV4 RNA was detected in affected respiratory epithelium in 73% (85/117) of evaluated cases.
"This was the first report associating PoAstV4 with respiratory pathology in neonatal and weaned pigs. The next step of research is to define the ability of PoAstV4 to cause clinical respiratory disease and associated lung lesions in naïve pigs," SHIC reports.
In the 2023 SHIC-funded study, researchers at North Carolina State University are collaborating with the USDA National Animal Disease Center, Iowa State University, and University of California Santa Cruz to evaluate PoAstV4 as a causative agent of respiratory disease in high health, colostrum deprived, caesarean-derived pigs.
"Utilizing these high health pigs avoids potential exposure to PoAstV4 and the transfer of PoAstV4 maternal antibodies from the sow to piglets," SHIC reports. "Pigs will be evaluated for the presence of clinical respiratory disease, evidence of gross and microscopic lesions, and presence of virus in multiple tissue types. Characterizing aspects of infection such as location of lesions, duration and peak virus quantity in tissues over time helps to inform veterinarians how to sample suspect cases for accurate diagnosis."
In addition, analysis of the immune response to PoAstV4 under a controlled setting will provide information on antibody production.
What's the goal of this research? SHIC says findings will assist veterinarians in the accurate diagnosis of PoAstV4 in pigs showing clinical signs of respiratory disease without a known etiology.
Knowledge gained from the one-year study will be shared with producers and veterinarians as soon as it becomes available, SHIC adds.
