Influenza A virus (IAV) presents as a global public health concern, resulting in an extensive burden on morbidity and mortality rates in humans. IAV has high mutation rates, influencing emergence of new virus strains, which could lead to increased antiviral resistivity and altered virulence. Although prevention and treatment of influenza infections have been improved, animal models still play a major role in understanding of host responses and the pathogenesis of IAV infection. Zebrafish are useful host models for evaluating infectious diseases processes, especially with the ability to manipulate the genome of zebrafish. Research by others have shown that parenteral applied IAV could infect zebrafish embryos, supporting that zebrafish could be used as a host model of IAV infection. In this study, our goal was to determine if viral host adaptation or mucosal perturbation will provide a more useful model by allowing routes of infection through the respiratory epithelium. The prototype strain A/Puerto Rico/8/1934(H1N1) (abbreviated as APR8) was selected and used in this study. To host adapt the virus we attempted to propagate APR8 in SJD and ZF zebrafish cell lines, and to infect zebrafish embryos at 24-48 hours post-fertilization. In the process, we found that the zebrafish embryos and cell lines were highly sensitive to the antibiotics and trypsin used in the medium to propagate the virus. We have therefore modified virus propagation procedures to optimize cell line production and embryo challenges. As a future study, once the adaption is successful, we will do comparative challenges of zebrafish embryos with parent strain and adapted virus, with and without mucosal perturbation. If successful, the zebrafish adapted virus can be used in pathogenesis, and innate defense research and comparative research will reveal the critical requirement for IAV adapting to a distant host
