Dynamics and evolution of swine influenza viruses in permanently infected pig herds in Europe (PIGIE)

Pig production has grown dramatically worldwide over the last 20 years, leading to increased herd sizes with weekly production cycles of piglets. In the meantime, the dynamics of infections with swine influenza A viruses (swIAV) have changed, from epizootic acute respiratory outbreaks to a self-sustaining infected status of affected herds. Moreover, the genetic and antigenic diversity of swIAVs in European pig populations has dramatically increased in recent years. Thus, novel reassortants and antigenic variants have emerged regionally, that can escape control strategies based on vaccines licensed for use in Europe. The self-sustaining forms of swine influenza (SI) in large holdings adversely affect animal health and welfare, and prompts the excessive use of antibiotics when swIAV is associated with other respiratory pathogens in the porcine respiratory disease complex (PRDC), resulting in severe economic losses. There is an urgent need to increase knowledge of within-herd virus dynamics and evolution in order to design intervention and prevention measures to limit swIAV persistence in intensive herds and counteract continuous production losses and emergence of new swIAVs.The objectives of the research project PIGIE are: – to define the epidemiological and economic factors that drive the prevalence and dynamics of swIAV in large pig herds, – to evaluate the impact that swIAV enzootic infections have on animal welfare, production parameters and economic productivity, – to study the genetic and antigenic diversity of swIAV in Europe, – to identify the host-pathogen factors that would foster swIAV evolution, – to provide a better understanding of long-lasting and protective immunological memory responses developed in the infected hosts, – to identify mitigation points in continuously infected herds, – to implement and evaluate control strategies that would help to counter sustained infections in closed intensive herds.