Complex Reassortment, Movement of Swine Influenza A in Cambodia Analyzed

Researchers have described the complex genomic landscape of swine influenza A in Southeast Asia. In a new paper appearing in the Proceedings of the National Academy of Sciences, an international team of researchers analyzed more than 4,000 nasal swabs collected from pigs in Cambodia. Via RT-qPCR, they found 72 samples positive for the influenza A virus and generated genomic sequences for 45 of those flu samples. The H1N1 flu subtype accounted for more than 82 percent of the viral samples, and the researchers further traced the evolutionary origins of the viral gene segments, which they found to be from diverse sources. Through a phylogenetic analysis, the researchers uncovered a unique reassortant of European avian-likeH1N2 swine influenza subtype in four samples that also had acquired the North American triple-reassortant internal gene. Meanwhile, the researchers tracked the source of swine flu for Southeast Asia into south central China. "Our results unmask an increasingly complex genomic landscape of swIAV in Southeast Asia that is shaped by repeated introduction and reassortment of virus lineages, a process that is known to heighten pandemic risk," the researchers write.