Wild migratory birds have the capability to spread avian influenza virus (AIV) over long distances as well as transmit the virus to domestic birds. In this study, swab and tissue samples were obtained from 190 migratory birds during close surveillance in Egypt in response to the recent outbreaks of the highly pathogenic avian influenza (HPAI) H5N1 virus. The collected samples were tested for a variety of AIV subtypes (H5N1, H9N2, H5N8, and H6N2) as well as other pathogens such as NDV, IBV, ILT, IBDV, and WNV. Among all of the tested samples, the HPAI H5N1 virus was found in six samples; the other samples were found to be negative for all of the tested pathogens. The Egyptian HPAI H5N1 strains shared genetic traits with the HPAI H5N1 strains that are currently being reported in Europe, North America, Asia, and Africa in 2021–2022. Whole genome sequencing revealed markers associated with mammalian adaption and virulence traits among different gene segments, similar to those found in HPAI H5N1 strains detected in Europe and Africa. The detection of the HPAI H5N1 strain of clade 2.3.4.4b in wild birds in Egypt underlines the risk of the introduction of this strain into the local poultry population. Hence, there is reason to be vigilant and continue epidemiological and molecular monitoring of the AIV in close proximity to the domestic–wild bird interface.

Avian reovirus (ARV) strains cause a variety of symptoms in chickens, including viral arthritis/tenosynovitis, a disease that has emerged as a significant cause of economic losses in commercial chicken flocks in recent years in various countries, including Egypt. Furthermore, ARV strains are frequently isolated from birds suffering from malabsorption. In the actual study, seventy-five samples were collected in 2021 and 2022 from broiler and vaccinated broiler breeder flocks at different farms in Giza Province, Egypt, with reovirus-like symptoms such as significant weight fluctuation and arthritis/malabsorption. ARV was screened using real-time PCR, and fifteen positive samples were detected (20%), which were then subjected to embryonated chicken egg (ECE) isolation and molecular characterization (11/15 sample) of a partial segment of the sigma (σ)C gene (S1-gene). Phylogenetically, nine strains were found to belong to genotypic cluster IV, with 82–89% identity with Israeli ARV 2018, and two strains belong to genotypic cluster V with a 78% nucleotide identity with Japan ARV 2021. No correlation between lesions and genotype was found. The strains under study had a low sequence identity (43–55%) when compared with various commercial vaccines belonging to genotypic cluster I (e.g., strain S1133). These findings imply that novel ARV genotypes representing clusters IV and V have recently been introduced to Egyptian poultry farms. A homologous vaccine is suggested; because this variation raises the possibility that commercial vaccines may not offer protection against circulating ARVs.

Background: Avian influenza viruses (AIVs) have been identified from more than 100 different species of wild birds around the globe. Wild migratory birds can act as potential spreaders for AIVs to domestic birds between different countries. Egypt is situated on important migratory flyways for wild birds between different continents. While much is known about circulation of zoonotic potential H5N1 and H9N2 AIVs in domestic poultry in Egypt, little is known about the pivotal role of migratory birds in the maintenance and transmission of the viruses in Egypt.Methods: Targeted AIV surveillance has been conducted in 2017 in different wetlands areas in Northern and Eastern Egypt.Results: AIV of subtype H5 was detected in two bird species. In addition, a novel reassortant strain of the H6N2 subtype was identified which reveals the continuous risk of new influenza virus(es) introduction into Egypt. This novel virus possesses a reassortant pattern originating from different AIV gene pools.Conclusions: Intervention control strategies should be performed to minimize the possible contact of domestic birds with wild birds to lower the risk of virus transmission at this interface. In addition, constant monitoring of AIVs in migratory birds is essential in the early detection of influenza virus introduction into Egypt.

The evolution and adaptation of highly pathogenic avian influenza (HPAI) viruses pose ongoing challenges for animal and public health. We investigated the pathogenic characteristics of the newly emerged H5N1/2022 and H5N8/2022 of clade 2.3.4.4b compared to the previously circulating H5N1/2016 of clade 2.2.1.2 in Egypt using both avian and murine models. All strains demonstrated a 100% mortality in chickens after intranasal inoculation (10⁶ EID50), while the H5N8/2022 strain showing significantly higher viral shedding (8.34 ± 0.55 log10 EID50). Contact transmission rates varied between strains (50% for the 2.3.4.4b clade and 100% for the 2.2.1.2 clade). In the mouse model, H5N1/2016 infection resulted in an 80% mortality rate with significant weight loss and virus replication in organs. In contrast, H5N8/2022 and H5N1/2022 had 60% and 40% mortality rates, respectively. An histopathological analysis revealed pronounced lesions in the tissues of the infected mice, with the most severe lesions found in the H5N1/2016 group. These findings suggest the decreased pathogenicity of the newer H5Nx strains in mammalian models, emphasizing the need for continued surveillance and adaptive control strategies.

Background: Infectious bronchitis virus (IBV) is a highly spreading, evolving virus that induces multiple manifestations, including respiratory, urinary, and reproductive symptoms, and presents a considerable risk to the Egyptian poultry sector. This study assessed various IBV vaccination protocols available in broiler populations comprising live attenuated vaccines such as IB Var II, 793/B (4/91), IB Primer, and H120 against the local novel IBV-GI-23.3 strain. Methods: Vaccines were administered to eight groups of SPF chicks at 1 day only or 1 + 14 days of age. Birds were challenged via the oculo-nasal route at 28 days of age using 10⁶ EID₅₀/0.2 mL/chick with the NewValley-1-EGYIBV-GI23.3-2023 local strain. Ciliostasis activity and the scores for histopathological lesions were evaluated at 7 days post-challenge (DPC). Virus shedding was monitored at 3, 5, and 7 DPC using the real-time RT-PCR method. Results: The ciliostasis test indicated that the vaccinated groups receiving the IB Primer + 4/91 vaccine regime at 1 day only or 1 + 14 days of age received the highest level of protection (65%, 68%, respectively). Similarly, administration of IB Primer + IB Var II at 1 + 14 days of age demonstrated substantial protection (63%). Conversely, administering the H120 + 4/91 vaccination protocol at days 1 and 14 resulted in a moderate level of protection (53%). Tracheal IBV shedding quantification and subsequent histopathological signs of trachea, proventriculus, bursa, and kidney degenerative changes were significantly lower in the vaccinated groups (especially the IB Primer + 4/91 vaccine regime at 1 day only or 1 + 14 days) than in the positive control groups. Conclusions: The heterologous combined IB Primer + 4/91 program demonstrated the most significant protective efficacy against the IBV field challenge strains compared with other vaccines in broiler chickens.

In recent years, the reintroduction of the infectious bursal disease virus (IBDV), particularly its severe strains, has imposed considerable cost on the Egyptian poultry industry. The goal of the current study was to investigate the molecular features of IBDV in Egypt from June 2019 to April 2021. A total of 30 field samples (bursa of Fabricius) were collected from broiler farms in which the chickens were vaccinated (Transmune 2512 s/c) at hatching. A highly variable region encompassing VP2 gene was targeted for IBDV screening utilizing reverse transcription-polymerase chain reaction (RT-PCR). Of 30 tested samples, 16 were positive by PCR. To isolate the virus, the bursal suspension was injected into 10-11 day embryonated chicken eggs via the chorioallantoic membrane. Five current positive isolates from 2021 were chosen for nucleotide and amino acid (aa) sequence analysis. Phylogenetically, three of the strains under study belonged to the very virulent (vvIBDV) strains, with 97-98% resemblance to Giza 2008 belonging to the (Genogroup 3) IBDV strain. The remaining two strains were identified as a vaccination strain (genotype 1) that matched the winter field 2512 vaccine strain by a similarity percentage of 98. Mutations in the antigenic locations of (P) domain loops were discovered when the sequencing samples were compared to the existing IBD vaccines. The circulating strains were found to be very similar to vvIBDV serotype 1 genotype 3 strains with mutations in the P domain loop providing a potential reason for the circulation of vvIBDV viruses in Egyptian broiler farms despite the vaccination program.