Virus persistence in pig herds led to successive reassortment events between swine and human influenza A viruses, resulting in the emergence of a novel triple-reassortant swine influenza virus

Amélie Chastagner,Stéphane Gorin,Nicolas Barbier,Yannick Blanchard,Emmanuel Garin,Nicolas Rose,Christelle Fablet,Gaëlle Simon,Véronique Béven,Edouard Hirchaud,Pierrick Lucas,Stéphane Quéguiner,Emilie Bonin,Séverine Hervé

doi:10.1186/s13567-019-0699-y

Abstract

This report describes the detection of a triple reassortant swine influenza A virus of H1avN2 subtype. It evolved from an avian-like swine H1avN1 that first acquired the N2 segment from a seasonal H3N2, then the M segment from a 2009 pandemic H1N1, in two reassortments estimated to have occurred 10 years apart. This study illustrates how recurrent influenza infections increase the co-infection risk and facilitate evolutionary jumps by successive gene exchanges. It recalls the importance of appropriate biosecurity measures inside holdings to limit virus persistence and interspecies transmissions, which both contribute to the emergence of new potentially zoonotic viruses.

Highlights

This report describes the detection of a triple reassortant swine influenza A virus of H 1avN2 subtype
This study reports the detection in France of a novel triple reassortant H1avN2 virus following two reassortment events that took place probably 10 years apart
Hemagglutination inhibition (HI) assays, performed using a reference panel of antigens representative for European swine Influenza A viruses (IAVs) [3], revealed the presence of antibodies directed against the hemagglutinin (HA) of H1avN1 viruses known to circulate in French pig herds since the early 80’ [4]

Summary

Introduction

This report describes the detection of a triple reassortant swine influenza A virus of H 1avN2 subtype. I.e., swIAV infection in each successive batch of pigs reared, was suggested to be associated to swIAV enzootic persistence at the herd level, a situation that would favor co-circulation of different swIAV subtypes and/or coinfection events with enzootic swIAVs and human IAVs, both situations being a prerequisite to the emergence of novel reassortant viruses [6, 7].

Results

Conclusion