Novel Human-like Influenza A Viruses Circulate in Swine in Mexico and Chile

Discussion Through new surveillance efforts and phylogenetic analysis of IAV-S in Mexico and Chile, we have expanded our understanding of the extensive IAV-S diversity that circulates in swine in Latin America. Most notably, we have identified multiple novel clades of H3N2 and H1N1 viruses of human origin in Mexico and Chile that have not been identified in swine previously, highlighting the importance of the human-swine interface in the evolution of IAV-S diversity in Latin America. The presence of two different IAV-S lineages in Mexico that are related to North American IAV-S (classical H1N1 and H3-cluster IV) also demonstrates the importance of viral migration from US and/or Canadian swine herds into Mexico. The identification of a group of human-origin H3 IAV-S isolates from swine in both Brazil and Chile could be evidence of IAV-S migration between two countries in Latin America, but additional sequence data are needed to rule out the possibility of two independent human-to-swine transmissions in these respective countries. The fact that live swine are not frequently transported between Brazil and Chile supports the likelihood of two independent introductions from humans, but additional data are greatly needed. Consistent with patterns observed globally16, at least 12 introductions of human H1N1pdm09 viruses in to swine were observed in Chile and Mexico since 2009, further contributing to IAV-S diversity. Overall, we identified four key evolutionary processes that genera...
Source: PLOS Currents Outbreaks - Category: Epidemiology Authors: Source Type: research