Experimental Efficacy of an Alphavirus Vectored RNA Particle Vaccine Against Porcine Parainfluenza Virus-1 in Conventional Weaned Pigs

TL;DR

This study tested an alphavirus-based RNA vaccine against a pig respiratory virus and found it reduced infection and shedding in weaned pigs.

Contribution

The study demonstrates the efficacy of an alphavirus-derived RNA particle vaccine against PPIV1 in conventional pigs.

Findings

RNA particle vaccination reduced PPIV1 shedding in nasal swabs by 5 days post-inoculation.

All vaccinated or exposed pigs developed antibodies, with RP vaccines inducing IgG and live exposure inducing IgA.

Vaccination significantly reduced PPIV1 antigen in lung, trachea, and nasal tissues compared to non-vaccinated pigs.

Abstract

Parainfluenza viruses are a common cause of respiratory illness in many species. In this study, experimental, alphavirus-derived RNA particle vaccines either with or without adjuvant were evaluated against porcine parainfluenza virus 1 (PPIV1) challenge and compared to live virus exposure. Groups of ten, three-week-old pigs were vaccinated intramuscularly with an adjuvanted RNA particle (RPAdj/C) or non-adjuvanted RP (RP/C) or administered an intranasal live exposure (LE/C) dose of PPIV1 at 0- and 21-days post vaccination (DPV) followed by challenge with PPIV1 at 40 DPV. In addition, two groups were included as non-vaccinated, non-challenged (NV/NC) and non-vaccinated, challenged (NV/C) controls. Intranasal virus exposure and RP vaccination, regardless of adjuvant, reduced PPIV1 shedding in nasal swabs by 5 days post inoculation (DPI). All vaccinated or exposed pigs seroconverted as shown by enzyme-linked immunosorbent assay and serum virus neutralization. The antibody isotype detected in bronchoalveolar lavage fluid (BALF) LE/C was predominantly IgA while RP vaccination induced an IgG response. Reduced PPIV1 antigen was observed in the LE/C, RP/C and RPAdj/C groups in lung, trachea, or nasal turbinate epithelium. Additionally, the RPAdj vaccine significantly reduced nasal shedding compared to NV/C pigs although not as much as LE/C pigs. These results suggest vaccination could mitigate PPIV1 infection in commercial systems.

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