الفهرس 
Title : Possible reassortment between highly pathogenic H5N1 and low pathogenic H9N2 avian influenza viruses and its impact on pathogenicity and infectivity
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Abstract
Due to the segmented nature of influenza viruses, the risk of reassortment is highly elevated in case of cocirculation and coinfection of different influenza subtypes in the same host. In Egypt, the cocirculation of HP H5N1 and LP H9N2 in Egyptian farms and the subsequent confirmed coinfection poultry cases raise the risk of causing new reassorted viruses that might cause new outbreak. To assess the potential risk of the IAV reassortants derived from these two subtypes, we generated, using reverse genetics technology of IAV, a set of IAV reassortants carrying the genetic segments of clade 2.2.1.2 influenza A/duck/Egypt/Q4596D/2012 (H5N1, most prevalent clade in Egypt) in the genetic backbone of an influenza A/chicken/Egypt/S4456B/2011 (H9N2) strain, a representative of G1-like H9N2 lineage which is widely circulating in Egypt. Furthermore, the genetic compatibility and growth kinetics of new viruses compared to the parent viruses using MDCK and A549 cell lines and SPF embryonated eggs. Pathogenicity and survival rates were also studied usig SPF embryonated eggs and SPF chickens. Out of eight H9-reassortants, we could rescue only five reassortant either due to difficulty in cloning (H5-PB1) or genetic incompatibility (H5-NP and H5-NA). Results revealed higher replication rates of the H9N2 virus carring NS segment of H9N2. Survival results showed that the lowest rate belongs to H5N1 parent virus followed by H9N2 virus having HA of H5N1. Our findings also suggest that all forms of generated reassortant viruses are lower in their pathogenicity than H5N1 virus