Distribution and persistence of atypical porcine pestivirus (APPV) in experimentally inoculated pigs

Authors: Buckley, Alexandra; Falkenberg, Shollie; Palmer, Mitchell; ARRUDA, PAULO - Iowa State University; MAGSTADT, DREW - Iowa State University; SCHWARTZ, KENT - Iowa State University; GATTO, IGOR - Sao Paulo State University (UNESP); Neill, John; ARRUDA, BAILEY - Iowa State University

Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2021
Publication Date: 6/2/2021
Citation: Buckley, A.C., Falkenberg, S.M., Palmer, M.V., Arruda, P.H., Magstadt, D.R., Schwartz, K.J., Gatto, I., Neill, J.D., Arruda, B.L. 2021. Distribution and persistence of atypical porcine pestivirus (APPV) in experimentally inoculated pigs. Journal of Veterinary Diagnostic Investigation. 33(5):952-955. https://doi.org/10.1177/10406387211022683.
DOI: https://doi.org/10.1177/10406387211022683

Interpretive Summary: Atypical porcine pestivirus (APPV) is a pestivirus that infects swine first discovered in 2015. Since then, APPV has been found in swine samples from apparent healthy animals around the globe, but recently a number of investigations into piglets with congenital tremors (CT), or shaker pigs, reported the presence of APPV. Experimental studies inoculating pregnant sows with the virus produced shaker pigs at birth supporting APPV as a causative agent for CT in pigs. Experimental studies have reported presence of the virus throughout various tissues in affected piglets, but there is limited information available about cellular location of the virus in various tissues. In addition, other pestiviruses have been reported to persist in animals even after clinical signs have resolved, so questions remain about the persistence of APPV. In this study, tissues were collected from piglets 2 days after birth that were born to sows inoculated at gestation with APPV. In addition, two boars from APPV inoculated sows that had CT were euthanized at 11 months of age. In situ hybridization, an assay that detects viral nucleic acid in tissues, was performed on tissue samples from both piglets and boars for comparison of localization and distribution of virus. A broad distribution of viral RNA labeling including endothelial cells, fibroblasts, smooth muscle, and brain. Labeling in tissues was more pronounced in piglet tissues compared to recovered boars, with the notable exception of diffuse labeling of the cerebellum in boars. Results from this study have better characterized location of APPV in tissues of acutely affected pigs. The presence of APPV in boar tissues well after resolution of clinical signs suggests persistence of the virus similar to other pestiviruses.

Technical Abstract: Atypical porcine pestivirus (APPV) is a cause of congenital tremors (CT) in piglets and has been found in swine populations across the globe. Though systemic distribution of the virus has been reported there is limited information available about cellular localization of the virus in various tissues. In this study, tissues were collected from piglets 2 days after birth that were born to sows inoculated at 45 or 62 days of gestation with APPV via three simultaneous routes: intravenous, intranasal, and directly in amniotic vesicles. In addition, two boars from APPV inoculated sows with CT were euthanized at 11 months of age. In situ hybridization performed on tissue samples from piglets demonstrated a broad and systemic distribution of viral RNA including endothelial cells, fibroblasts, and smooth muscle. Labeling in tissues was more pronounced in piglet tissues compared to boars, with the notable exception of diffuse labeling of the cerebellum. Presence of APPV in boar tissues well after resolution of clinical signs suggests persistence of the virus similar to other pestiviruses.