Swine influenza A viruses (swIAVs) can play a crucial role in the generation of new human pandemic viruses. In this study, in-depth passive surveillance comprising nearly 2,500 European swine holdings and more than 18,000 individual samples identified a year-round presence of up to four major swIAV lineages on more than 50% of farms surveilled. Phylogenetic analyses show that intensive reassortment with human pandemic A(H1N1)/2009 (H1pdm) virus produced an expanding and novel repertoire of at least 31 distinct swIAV genotypes and 12 distinct hemagglutinin/neuraminidase combinations with largely unknown consequences for virulence and host tropism. Several viral isolates were resistant to the human antiviral MxA protein, a prerequisite for zoonotic transmission and stable introduction into human populations. A pronounced antigenic variation was noted in swIAV, and several H1pdm lineages antigenically distinct from current seasonal human H1pdm co-circulate in swine. Thus, European swine populations represent reservoirs for emerging IAV strains with zoonotic and, possibly, pre-pandemic potential.

猪A型流感病毒（swIAV）在新的人类大流行病毒的产生中可以发挥关键作用。在这项研究中，由近2500家欧洲猪场和18000多个个体样本组成的深度被动监测确定，在超过50％的受监视农场中，全年存在多达四个主要的swIAV血统。系统发育分析表明，与人类大流行性A（H1N1）/ 2009（H1pdm）病毒的强烈重配产生了至少31种不同的swIAV基因型和12种不同的血凝素/神经氨酸酶组合的扩展且新颖的库，其毒力和宿主嗜性的后果很大程度上未知。几种病毒分离株对人抗病毒MxA蛋白有抗性，这是人畜共患病传播和稳定引入人类的先决条件。在swIAV中发现了明显的抗原变异，并且在抗原上不同于当前季节性人类H1pdm的H1pdm谱系在猪中共同传播。因此，欧洲猪群代表了具有人畜共患病和大流行前潜力的新兴IAV病毒株的库。