Seroprevalence of H3N2 influenza virus in pigs
There was only one monophyletic lineage of H3 SIVs isolated in our samples, that being the BD-like H3 lineage. H3N2 seroprevalence was assessed in 6,532 sets of paired nasal swabs and sera. The HAI seroprevalence of BD-like H3 SIVs in this subset was 20.5% (1,340/6,532) with HAI titer ≥1:40 against the reference H3 strain (A/swine/Hong Kong/4348/2016). The virus isolation rates and seroprevalence of H3N2 in swine were shown in Figure 2. No seasonal pattern was identified.