Evaluating Genetic Diversity and Dynamics of Virus Infection in Wean-to-Finish Pigs

January 28, 2015 — 

The objectives were to estimate the diversity of IAV in an infected growing pig population, and to determine the extent of re-infection with resident viruses. This is important to understanding why IAV persist in swine populations. We selected 132 weaned pigs that tested positive for the virus, and submitted samples for whole genome sequencing. Three genetically distinct viruses were identified in the population that caused two distinct IAV epidemics. A significant percentage of pigs became re-infected with IAV, usually with a different subtype. However, some pigs became re-infected with the same subtype but a different strain; others became re-infected with the same strain. Our results provide the first basic understanding on influenza virus diversity and transmission in pigs after weaning. We identified conditions for IAV persistence and reassortment. Our results should assist in the development of better vaccines and strategies to control and reduce the impact of IAV in pigs.

Principal Researcher: Dr. Montse Torremorell, DVM, University of Minnesota

Key Points:

• Influenza A virus (IAV) spreads rapidly after weaning; all pigs became infected despite immunity.
• Multiple IAV strains and subtypes can co-circulate within a population at different levels.
• Most pigs became re-infected with IAV, often with a different subtype but there were exceptions.

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