Although swine are natural hosts for influenza A viruses the porcine T-cell response to swine influenza A virus (FLUAVsw) LY2801653 dihydrochloride infection has been poorly characterized so far. contamination. These cells produced higher amounts of IFN-γ TNF-α and IL-2 than did CD4+ T cells that only produced a single cytokine. The vast majority of cytokine-producing CD4+ T cells expressed CD8α a marker associated with activation and memory formation in porcine CD4+ T cells. Analysis of CD27 expression suggested that FLUAVsw-specific CD4+ T cells included both central memory and effector memory LY2801653 dihydrochloride populations. Three out of six animals showed a strong increase of Ki-67+perforin+ CD8β+ T cells in blood one week post contamination. Blood-derived FLUAVsw-specific CD8β+ T cells could be identified after an in vitro expansion phase and were multifunctional in terms of CD107a expression and co-production of IFN-γ and TNF-α. These data show that multifunctional T cells are generated in response to FLUAVsw contamination of pigs supporting the idea that T cells contribute to the efficient control of contamination. Electronic supplementary material The online version of this article (doi:10.1186/s13567-015-0182-3) contains supplementary material which is available to authorized users. Introduction Pigs are natural hosts for influenza A viruses and infections of humans with swine influenza A viruses (FLUAVsw) have been reported . Moreover the pig is considered as a “mixing vessel” i.e. a species where reassortments between avian and mammalian influenza virus strains can occur which may lead to the emergence of novel pandemic strains in humans. For Rabbit polyclonal to ZNF248. example in the 2009 2009 pandemic H1N1 virus genes closely related to swine North American and Eurasian H1N1 viruses were identified . The 2009 2009 pandemic H1N1 virus was frequently transmitted from farmers to pigs during the last years thereby reflecting the zoonotic potential of this virus. As a consequence this transmission established a new lineage of pandemic viruses (pandemic H1N2) in pigs via reassortment with circulating swine influenza viruses . These observations but also economic and animal welfare issues of FLUAVsw infections in pig production units justify investigations on pig-FLUAVsw host-pathogen interactions. Of note FLUAVsw infections are usually rapidly controlled by the porcine immune system and an elimination of replicating virus from the respiratory tract within one week has been reported . Neutralizing antibodies appear in serum within seven days post inoculation . It is assumed that these antibodies play a major role in control of contamination although LY2801653 dihydrochloride a production of IgA antibodies by B cells in the nasal mucosa has also been reported . The rapid control of FLUAVsw infections suggests that also cell-mediated immune responses contribute to viral clearance. However while abundant knowledge exists around the role of influenza virus-specific CD4+ and CD8+ T cells in mice and humans  their role has not been studied in great detail in pigs. A FLUAVsw-specific proliferation of lymphocytes isolated from blood has been reported following contamination of pigs with H3N2 and H1N1 FLUAVsw strains [7-9]. One study exhibited LY2801653 dihydrochloride the proliferation of blood-derived CD4+ and CD8+ T cells following vaccination with a human pandemic H1N1 vaccine . Also the presence of H1N1-specific IFN-γ producing T cells in tracheobronchial lymph nodes spleen and nasal mucosa has been described . More recently increased frequencies of cytolytic T cells (CTLs) CD4+CD8α+ T cells and regulatory T cells have been reported in lung tissue and bronchoalveolar lavage fluid of H1N1-infected pigs six days post contamination . However none of these studies LY2801653 dihydrochloride investigated the phenotype and functional properties of FLUAVsw-specific T cells in detail. Taking into account the rapid clearance of FLUAVsw infections we hypothesized that highly differentiated CD4+ and CD8β+ T cells with multiple effector functions are involved in protective LY2801653 dihydrochloride immune responses. Accordingly we performed a detailed phenotypic and functional analysis of FLUAVsw-specific T cells occurring in blood of pigs experimentally infected with a FLUAVsw H1N2 isolate. Materials and methods Animals and virus Nine three-week-old crossbred piglets ([Landrace?×?Large White]?×?Pietrain) were derived from a conventional breeding.