earticle

영어

Following repeated reverse-zoonoses of the pandemic H1N1 (pH1N1) 2009 virus in swine populations, novel reassortants between pH1N1 and endemic swine viruses have been detected from pigs worldwide. Through an active surveillance program in pig abattoirs between fall 2011 to spring 2012, we identified reassortant H3N2 and H3N1 swine viruses in Chungbuk Province, South Korea. Whole-genome characterization revealed that the reassortant H3N2 viruses are more genetically closely related to novel H3N2 (rH3N2p) viruses recently detected in North America containing the pandemic matrix gene, which also caused sporadic human infections, rather than previous Korean isolates. In contrast, the variant H3N1 reassortant (rH3N1p) viruses represent four novel genotypes in the backbone of pH1N1. Comparison of growth properties in vitro showed that selected rH3N2p and rH3N1p viruses had comparable kinetics in MDCK and A549 cells but the variant rH3N1p viruses exhibited growth advantage in HBE cells; only three of the 4 rH3N1p viruses persisted in the lungs of infected mice up to 7 dpi but none demonstrated altered virulence. All viruses tested replicated well in the upper respiratory tract of ferrets. Furthermore, serology indicated that these H3 reassortant viruses are antigenically divergent from recent human seasonal H3N2 strains suggesting previous exposure or vaccination may provide limited immunity against these viruses. Establishment of these novel viruses in Korean pigs could increase genetic diversity of endemic swine viruses which may pose threat to public health. Data underscores the need for continuous monitoring to evaluate genetic evolution in this ecologically important virus reservoir.