Virological and epidemiological patterns of swine influenza A virus infections in France: Cumulative data from the RESAVIP surveillance network, 2011–2018

Evaluation of the Pathogenicity and the Escape from Vaccine Protection of a New Antigenic Variant Derived from the European Human-Like Reassortant Swine H1N2 Influenza Virus

“…Additional mutations that were observed in NA may have been introduced in response to the modifications in HA to re-establish the HA/NA functional balance, leading to a modification of virulence. Intriguingly, deletions 146 and/or 147 have been identified in H1 of many swIAV virus strains worldwide [ 3 , 5 , 6 , 7 , 8 , 9 ], whereas these viruses were of different viral origins and they belonged to different lineages. This genetic evolution would certainly tend to bring an advantage for the virus; in vitro analyses using recombinant viruses produced by reverse genetics would allow for a better understanding of this phenomenon.…”

“…If confirmed, escaping vaccine immunity could give an advantage to the variant that could possibly become enzootic. In France, even though the proportion of H1 hu N2 Δ14–147 strains among the H1 hu N2 viruses has decreased since 2015, they are still detected every year, which confirms the virus maintenance within the pig population [ 3 ]. Therefore, it is necessary to follow further genetic and antigenic evolutions of this variant that diverges from the vaccine antigen.…”

“…Given the impact of swIAV in terms of animal health and public health due to zoonotic potential, monitoring the circulation and evolution of virus strains has been encouraged in many countries after the last influenza pandemic in 2009. In France, swIAV surveillance highlighted the emergence in 2012 of a new antigenic variant of H1N2 subtype, which results from a genetic drift in the H1 hu N2 virus circulating since the ‘90s (“Scotland/94” lineage; HA clade 1B.1.2.3) [ 2 , 3 ]. The haemagglutinin (HA)-encoding gene of the variant exhibits mutations in several antigenic sites, as well as two successive amino acid deletions at residue positions 146–147 (129–130 when H1 numbering without signal peptide), which are located in the cell receptor binding site (RBS) [ 2 , 4 ].…”

“…The haemagglutinin (HA)-encoding gene of the variant exhibits mutations in several antigenic sites, as well as two successive amino acid deletions at residue positions 146–147 (129–130 when H1 numbering without signal peptide), which are located in the cell receptor binding site (RBS) [ 2 , 4 ]. The proportion of new variant H1 hu N2 Δ14–147 strains that were detected over the country among the H1 hu N2 viruses increased until reaching 50% in 2013–2014 [ 3 ]. Interestingly, other swIAV strains exhibiting a H1 glycoprotein with similar amino acid deletions into the RBS at positions 146 and/or 147 have been described elsewhere, whereas belonging to other HA-1B (H1 hu ) clades, e.g., 1B.1.2.2 in Italy [ 5 , 6 ] and 1B.2-1B.1-like in Russia [ 7 ], but also to other H1 lineages, e.g., 1A.1.1 (classical swine or H1α3) in North America [ 8 ] and 1C.2 (H1 av ) in France [ 9 ].…”

Assessment of Influenza D Virus in Domestic Pigs and Wild Boars in France: Apparent Limited Spread within Swine Populations Despite Serological Evidence of Breeding Sow Exposure

“…At the European level, differences in serological and virological positive rates between France and Italy may relate to the herd types where the samples were obtained, and more globally to herd management practices. In France, most of tested sera came from farrow-to-finish herds, as the three quarters of farms where pigs with clinical respiratory signs are sampled for diagnosis analyses are from that herd type [32]. By contrast, in Italy, the herds included in the assessment of IDV infections were only finishing farms and the sampled pigs were older [7].…”