MISMS researchers characterized the high levels of genetic diversity of influenza viruses circulating in swine in Mexico, working closely with veterinarians in Mexico and with funding from a major animal vaccine manufacturer. The study is available online at Emerging Infectious Diseases and will be published in print next month. The study was a collaboration between the NIH, USDA, and University of Minnesota, which performed the genetic sequencing of the viruses. USDA performed antigenic cartography to visualize how the host immune system ‘sees’ virus lineages differently. MISMS staff performed the phylogenetic analysis, which showed that the viral diversity seen in Mexican swine comes primarily from humans (reverse zoonosis) and US exports of live hogs to Mexico. The direction of trade of live hogs between countries is critical in shaping where viruses are found globally.