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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #420386
Research Project: Intervention Strategies to Control Endemic and New Emerging and Re-Emerging Viral Diseases of Swine

Location: Virus and Prion Research

Title: Porcine astrovirus 4 as a cause of tracheitis and bronchitis in pigs

Author
item RAHE, MICHAEL - North Carolina State University
item STEPHENS, JAZZ - North Carolina State University
item DERSCHEID, RACHEL - Iowa State University
item KO, CALVIN - Iowa State University
item NOEL, ANDREW - Iowa State University
item GAUGER, PHIL - Iowa State University
item SITTHICHAROENCHAI, PANCHAN - North Carolina State University
item GROELTZ-THRUSH, JENNIFER - Iowa State University
item DUBOIS, REBECCA - University Of California Santa Cruz
item HALEY, DANIELLE - University Of California Santa Cruz
item Devries, Alexandra

Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: OBJECTIVE: Astroviruses are single-stranded RNA viruses shown to be associated with gastroenteric and neurologic disease in several animal species, including humans. Porcine astrovirus 4 (PoAstV4) has previously been associated with clinical respiratory disease and lesions of tracheitis and bronchitis in pigs; however, experimental reproduction of respiratory disease has not been performed. The objective of this study was to fulfill Koch’s postulates with PoAstV4 inoculum. METHODS: Four-week-old cesarean-derived colostrum-deprived piglets (n=18 challenged and n=11 negative controls) were inoculated with a PoAstV4 positive tissue homogenate through both intratracheal and intranasal routes. Inoculum was previously screened with NGS for other primary pathogens of swine. Nasal swabs, fecal swabs, and serum were collected throughout the study. One third of the pigs were euthanized on day post-challenge 5 (DPC5) for trachea and lung tissue collection. Another one third of pigs were euthanized on DPC8 with the final pigs were sacrificed on DPC 21. PoAstV4 PCRs were run on swabs, tissue, and serum. PoAstV4 RNAScope in situ hybridization and CD3 and CD20 immunohistochemistry were run on sections of trachea and bronchi with QuPath evaluation for scoring of direct detection signal. RESULTS: PoAstV4 PCR results on nasal swabs showed a robust infection with peak shedding detected at 6 days post-challenge (6DPC). Seroconversion against PoAstV4 was achieved, with IgG against the capsid spike protein detected at 14DPC and an IgM curve starting at DPC5, peaking at DPC14 and decreased by DPC21. Histologic scoring of the trachea and bronchi revealed lesions of epitheliotropic viral infection with mononuclear infiltration of the lamina propria in challenged pigs. Infection of the epithelium of the nasal turbinates, tracheas, and bronchi of challenged pigs at 5DPC was confirmed with PoAstV4 in situ hybridization (ISH) with quantitative assessment pending. Additionally, the characterization of the lamina propria mononuclear infiltrate with CD3 and CD20 immunohistochemistries is ongoing. CONCLUSIONS: These findings show that PoAstV4 is a cause of tracheitis and bronchitis in pigs and subsequent analysis will further characterize both the infection and the host immune response.