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Infectious bronchitis virus (IBV) continues to circulate worldwide, with a significant impact on the poultry industry and affecting both vaccinated and unvaccinated flocks. Several studies have focused on the hypervariable regions (HVRs) of the spike gene (S1); however, genetic and bioinformatics studies of the whole S1 gene are limited. In this study, the whole S1 gene of five Egyptian IBVs was genetically analyzed. Phylogenetic analysis revealed that the Egyptian IBVs are clustered within two distinct groups: the classic group resembling the GI-1 genotype (vaccine strains) and the variant group (field strains) of the GI-23 genotype. The variant genotype was divided into two distinct subgroups (Egy/var I and Egy/var II) resembling the Israeli variants IS/1494 and IS885 strain, respectively. Significant amino acid sequence differences between the two subgroups, especially in the epitope sites, were identified. A deletion at position 63 and an I69A/S substitution mutation associated with virus tropism were detected in the receptor-binding sites. The deduced amino acid sequence of HVRs of the variant subgroups indicated different genetic features in comparison to the classic vaccine group (H120 lineage). The Egyptian variant IBVs also contained additional N-glycosylation sites compared to the classical viruses. Recombination analysis gave evidence for distinct patterns of origin by recombination throughout the S1 gene, suggesting that the recent virus IBV-EG/1586CV-2015 emerged as a recombinant of two viruses from the variant groups Egy/var I and Egy/var II, providing another example of intra-genotypic recombination among IBVs and the first example of recombination within the GI-23 genotype. Our data suggest that both mutation and recombination may be contributing to the emergence of IBV variants. Moreover, we found that the commercially used vaccines are genotypically distant from the circulating field strains. Hence, continuous follow-up of the current vaccine strategy is highly recommended for better control and prevention of infectious bronchitis virus in the poultry sector in Egypt.

Since 2006, in Egypt, highly pathogenic avian influenza virus (HPAIV) H5N1 has established endemic status in poultry. Bayesian evolutionary analysis sampling trees suggested an introduction date in the third quarter of 2005. Evolutionary dynamics using Bayesian analysis showed that H5N1 viruses of clade 2.2.1.1 evolved at higher rates than those of clade 2.2.1.2. Bayesian skyline plot analysis of the HA gene of 840 and NA gene of 401 Egyptian H5N1 viruses from 2006-2015 identified two waves of viral population expansion correlating with the stepwise emergence of the 2.2.1.1 variant lineage in 2008 and with the newly emerging 2.2.1.2 cluster in late 2014. H5N1 infections in human hosts in 2014-2015 were statistically linked to a contemporary poultry outbreak.