Fowl adenoviruses (FAdVs) are a large group of viruses of different serotypes. They are responsible for inclusion body hepatitis, adenoviral gizzard erosion, and hepatitis hydropericardium syndrome. The present study presents a comprehensive overview of FAdVs in Egypt, with a focus on the epidemiological features of virus serotypes across the country. We conducted molecular investigation of multiple FAdV species based on the genetic signature of hypervariable regions 1–4 in the loop1 (L1) region of the hexon gene. Epidemiologically, the Nile Delta governorates showed high positivity of FAdVs, which were more commonly found in broilers than in layers. Genetically, species D and serotype 8a/E dominated, and the findings also revealed the emergence of new FAdV serotypes 1, 3, and 8b. The comparative analysis of hypervariable regions in the L1 region of the hexon gene revealed variables specific to each virus serotype. In silico predictions of L1 region revealed variations in the molecular structure and predicted the antigenic epitopes which may affect the cross-antigenicity between the different FAdV species and serotypes.

Since the introduction of H9N2 low pathogenic avian influenza virus in Egypt, it became an endemic disease causing considerable economic losses in different poultry sectors especially in the presence of other secondary bacterial and viral infections. The H9N2 viruses in Egypt are in continuous evolution that needs deep analysis for their evolution pattern based on the genetic constitutions of the pathogenic determinant genes (HA, PB2, PB1, PA, and NS). In this work, samples were collected from the backyard chickens from 3 Egyptian governorates. Five selected viruses were sequenced and analyzed for the hemagglutinin gene which showed genetic relatedness to the Asian G1 lineage group B, similar to the circulating H9N2 viruses in Egypt since 2013. The sequence for PB2, PB1, PA, HA and NS genes of the selected five viruses indicate a natural re-assortment event with recent Eurasian subtypes and similar to Egyptian H9N2 virus isolated from pigeon in Egypt during 2014. The Egyptian viruses of our study possess amino acids signatures including S42, V127, L550, L672 and V504 in the internal genes NS1, PA, and PB2, of respectively of an impact on virus transmission and replication. This work indicates that the H9N2 is in continuous evolution with alarming to the reassortment occurrence.

The highly pathogenic avian influenza (HPAI) H5N8 virus was first detected in Egypt in late 2016. Since then, the virus has spread rapidly among different poultry sectors, becoming the dominant HPAI H5 subtype reported in Egypt. Different genotypes of the HPAI H5N8 virus were reported in Egypt; however, the geographic patterns and molecular evolution of the Egyptian HPAI H5N8 viruses are still unclear. Here, extensive epidemiological surveillance was conducted, including more than half a million samples collected from different poultry sectors (farms/backyards/live bird markets) from all governorates in Egypt during 2019–2021. In addition, genetic characterization and evolutionary analyses were performed using 47 selected positive H5N8 isolates obtained during the same period. The result of the conducted surveillance showed that HPAI H5N8 viruses of clade 2.3.4.4b continue to circulate in different locations in Egypt, with an obvious seasonal pattern, and no further detection of the HPAI H5N1 virus of clade 2.2.1.2 was observed in the poultry population during 2019–2021. In addition, phylogenetic and Bayesian analyses revealed that two major genotypes (G5 and G6) of HPAI H5N8 viruses were continually expanding among the poultry sectors in Egypt. Notably, molecular dating analysis suggested that the Egyptian HPAI H5N8 virus is the potential ancestral viruses of the European H5N8 viruses of 2020–2021. In summary, the data of this study highlight the current epidemiology, diversity, and evolution of HPAI H5N8 viruses in Egypt and call for continuous monitoring of the genetic features of the avian influenza viruses in Egypt.

Background and Aim: Biosecurity implementation is fundamental to combating diseases and antibiotic resistance. Therefore, this study aimed to examine the correlation between the implementation of biosecurity measures in small-scale duck farms and the incidence of infectious diseases that threaten the duck industry. Materials and Methods: Twenty small-scale duck farms of different breeds and production stages were collected as representative samples, focused on two districts in the Qalyoubia governorate, which possesses high-density small-scale farms. A 30-point structured questionnaire was designed to assess the level of biosecurity measures implemented in the sampled farms. These farms were examined for bacterial infection by cultivation, typing, and antibiotic sensitivity tests, in addition to molecular techniques for detecting suspected viral diseases. Results: The results showed that the farms had high or low levels of biosecurity; only 25% possessed high-level biosecurity. Bacteria, including Salmonella, Escherichia coli, Staphylococcus, and Pasteurella, were isolated from all sampled farms. High rates of antimicrobial resistance-reaching up to 100% were observed against some drugs. However, viral causative agents, including HPAI-H5N8, duck viral hepatitis, and goose parvovirus, were isolated from only five farms. Conclusion: The lack of commitment to biosecurity implementation, particularly personal hygiene, was observed in most sampled farms. Increasing the level of biosecurity reduced the incidence of mixed infections. Keywords: antibiotic resistance, bacterial agents, biosecurity, co-infections, small-scale duck farms, viral diseases.

Identification of avian infectious bronchitis virus (IBV) genotypes is essential for controlling infectious bronchitis (IB) disease, because vaccines that differ from the circulating strains might not provide efficient cross-protection. In Egypt, IBV strain typing is a difficult process, due to the widespread distribution of four genotype lineages (GI-13, GI-23, GI-1, and GI-16), which may contribute to IBV vaccination failure. In this study, we developed a multiplex real-time quantitative reverse transcription polymerase chain reaction (mRT-qPCR) assay that targets highly conserved areas of the S1 gene in order to detect classical (G1) and Egyptian variant II (G23) strains in allantoic fluids and clinical samples. The viral genotyping technique was assessed using commercially available vaccines as well as local strains, and 16 field isolates were tested to investigate its clinical applicability. The assay was found to be specific for the detection of classical and VAR II strains and did not detect the VAR I strain or other avian pathogens such as Newcastle disease virus, avian influenza virus (H9N2 and H5N8), or infectious bursal disease virus. The results also showed that 28 out of 41 samples tested positive for IBV utilizing rt-qRT-PCR targeting the N gene and that 26 out of the 28 positive samples were genotyped by mRT-qPCR targeting the S1 gene, whereas the remaining two samples that were not genotyped were VAR 1 (4/91) and VAR I (793/B). Interestingly, the testing could identify combined infections in one sample, indicating a mixed infection with both genotypes. The real-time RT-PCR assay could detect viral RNA at concentrations as low as 10² EID₅₀ /ml for both classical and variant II. This assay is rapid, specific, and sensitive. It appears to be a valuable tool for regular disease monitoring that can be used to differentiate as well as identify viruses.