Identification of human derived swine influenza viruses with zoonotic potential
Rodrigo Tapia1, Bárbara Brito1,2, Marco Saavedra2, Juan Mena1, Tamara Garcia2,3, Gonzalo Barriga2, Raveen Rathnasinghe2, Victoria García1, Monserrat Torremorell3, Victor Neira1, Rafael A. Medina2,4,5
1Dept. Preventive Medicine, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile; 2Dept. of Pediatric Infectious Diseases and Immunology, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; 3Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, USA; 4Millennium Institute on Immunology and Immunotherapy. 5Dept. of Microbiology, Icahn School of Medicine at Mount Sinai, New York, USA
In 2009 a novel swine Influenza virus (swIAV) emerged causing a global pandemic that highlighted swine as a major host for the genesis of reassortant IAVs. There is only limited information of the swIAVs circulating in Latin America, where swine production is rapidly growing. We assessed the origin and genetic and antigenic diversity of sw-IAVs present in Chile. We identified two genetically and antigenically novel swH1N2 IAVs (H1N2ChA and H1N2ChB) and a low incidence divergent swH3N2 virus, that co-circulate with a 2009 H1N1 pandemic-like strain (A(H1N1)pdm09-like) in Chilean swine. Phylogenetic analysis revealed that the swIAVs originated from several human-to-swine introductions occurring as early as the mid 1980s, with up to 7 introduction of the A(H1N1)pdm09 IAV since 2009. All viruses contained the A(H1N1)pdm09 internal genes, implying a displacement of previous internal cassettes. Antigenic characterization revealed the presence of drifted variants in some farms. We found a substantial divergence of the swH1N2ChA, swH1N2ChB and swH3N2 viruses as compared to human IAV genomes available globally since 1977 and sequenced Chilean human viruses from 2009-2013. Human sera from the general population showed a mid to low-level antibody mediated protection against swH1N2ChA, swH1N2ChB and A(H1N1)pdm09-like viruses and a poor protection against virus swH3N2, highlighting the zoonotic potential of this strain. Our results underscore the importance of understanding swIAVs in Latin America to be better prepared against zoonotic events.
Funding: Fondecyt 11170877, PIA Anillo ACT 1408, all from CONICYT, and the NIAID-NIH Centers of Excellence in Influenza Research and Surveillance contract HHSN272201400008C.