Simultaneous Infection With Porcine Reproductive and Respiratory Syndrome and Influenza Viruses Abrogates Clinical Protection Induced by Live Attenuated Porcine Reproductive and Respiratory Syndrome Vaccination

• DOI: 10.3389/fimmu.2021.758368
• Publication Date: 2021-11-11T08:23:02Z
• Authors: Tiphany Chrun; Emmanuel A. Maze; Eleni Vatzia; Veronica Martini; Basudev Paudyal; Matthew D. Edmans; Adam McNee; Tanuja Manjegowda; Francisco J. Salg...; Nanchaya Wanasen; Surapong Koonpaew; Simon P. Graham; Elma Tchilian
• Keywords: pig; Swine; Datasets as Topic; FOS: Health sciences; Antibodies, Viral; Madin Darby Canine Kidney Cells; Agricultural and Biological Sciences; Context (archaeology); Viral load; 0303 health sciences; Coinfection; Vaccination; Life Sciences; porcine reproductive and respiratory syndrome virus; Viral Load; Virus; 3. Good health; Infectious Diseases; Porcine reproductive and respiratory syndrome virus; Cytokines; Medicine; Female; Porcine Reproductive and Respiratory Syndrome Virus; Immunology; Porcine Reproductive and Respiratory Syndrome; Vaccine Efficacy; Vaccines, Attenuated; swine influenza A virus; 03 medical and health sciences; co-infection; Dogs; Orthomyxoviridae Infections; Biochemistry, Genetics and Molecular Biology; Virology; Health Sciences; Genetics; Animals; Porcine respiratory and reproductive syndrome virus; Viremia; Viral Diseases in Livestock and Poultry; Biology; live attenuated vaccine; Influenza A Virus, H3N2 Subtype; FOS: Clinical medicine; Gastrointestinal Viral Infections and Vaccines Development; Paleontology; Viral Vaccines; RC581-607; FOS: Biological sciences; Animal Science and Zoology; Immunologic diseases. Allergy; Gene Therapy Techniques and Applications

The porcine respiratory disease complex (PRDC) is responsible for significant economic losses in the pig industry worldwide. Porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza virus are major viral contributors to PRDC. Vaccines are cost-effective measures for controlling PRRS, however, their efficacy in the context of co-infections has been poorly investigated. In this study, we aimed to determine the effect of PRRSV-2 and swine influenza H3N2 virus co-infection on the efficacy of PRRSV modified live virus (MLV) vaccination, which is widely used in the field. Following simultaneous challenge with contemporary PRRSV-2 and H3N2 field isolates, we found that the protective effect of PRRS MLV vaccination on clinical disease and pathology was abrogated, although viral load was unaffected and antibody responses were enhanced. In contrast, co-infection in non-immunized animals reduced PRRSV-2 viremia and H3N2 virus load in the upper respiratory tract and potentiated T cell responses against both PRRSV-2 and H3N2 in the lung. Further analysis suggested that an upregulation of inhibitory cytokines gene expression in the lungs of vaccinated pigs may have influenced responses to H3N2 and PRRSV-2. These findings provide important insights into the effect of viral co-infections on PRRS vaccine efficacy that may help identify more effective vaccination strategies against PRDC in the field.