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Avian influenza virus (AIV) poses a serious problem among poultry production sector, low pathogenic avian influenza H9N2 (LPAI H9N2) has been widely spread globally inducing indirect huge economic losses and it considered as a hidden threaten due to its immunosuppressive impact on birds. Therefore, the current work objectives were the molecular detection of the circulating AI H9N2 field strain in Egypt during 2022-2023 with pathogenicity testing of the recovered virus in specific pathogen free (SPF) one day old chicks. Out of 10 suspected tracheal samples that have been collected from different broiler chicken farms in Al Qalyubia governorate only 7 (70%) samples were positive by Reverse transcription Polymerase chain reaction (RT-PCR). The strain that showed a high reproductive ability and high egg infective dose 50 (EID50) (109/μl) on ECE via allantoic sac has been selected for pathogenicity testing in SPF chicks. For pathogenicity testing, 60 SPF chicks were allocated into two groups 30 birds each. G1and G2 were inoculated via oculo-nasal route with 100 μl containing 1x 106 EID50/μl virus and 100μl sterile normal saline, respectively. During the experimental time (15 days), no mortalities were recorded in the two groups. The observed clinical signs were mild (ruffled feathers, and depression) in G1, but no clinical signs were observed in G2. During the experiment 3 birds per group were ethically slaughtered to observe the postmortem (PM) and histopathological lesions at 3, 5, 7, 10 and 14 days post-infection (dpi). The observed PM lesions were mild tracheitis, mild pneumonia, subcapsular hemorrhage in liver, enlargement of the spleen, mild atrophy in the pancreas, hemorrhage in the thymus, severe nephritis, and nephrosis with distended ureters with ureates but no macroscopic lesions were detected in the bursa of Fabricius. The virus tropism not restricted only to respiratory, renal, and gastrointestinal tract, but also to the liver, pancreas, and thymus. In conclusion, continuous molecular detection, with pathogenicity testing of circulating AIV is recommended. The authors recommend further full H9 sequence to perform cladogram to the currently tested strain. [ABSTRACT FROM AUTHOR]

Avian leukosis virus (ALV) is an oncogenic contagious virus infecting different avian species. This study aims to molecularly detect the circulating strains of ALV in various chicken and duck farms at different Egyptian governorates. Freshly dead birds were exposed for postmortem examination (PM) then samples were processed for histopathological examination as well as molecular detection of ALV using qRT-PCR and sequence analysis of the envelope glycoprotein gene (gp85) surface protein antigen with detection of recombination events that might be found between the detected strains. PM revealed the existence of diffuse enlargement of most internal organs, and in some cases, nodular enlargement was observed. Histopathological investigation showed myeloid cells infiltration of eosinophilic granular cytoplasm in the examined tissues. Five molecularly positive samples were sequenced and submitted in the GenBank with accession numbers MZ614719, MZ614720, MZ614721, MZ614722, and MZ614723. The phylogenetic tree construction based on the sequenced gp85 gene revealed that all Egyptian isolates were nearly arranged in a single branch despite the year of collection and were phylogenetically distant from other sequences. In general, studies concerning the genetic diversity of gp85, and the recombination events concluded that the ALV-J virus is a wide host range involving both chicken and ducks. Because ALV causes serious financial problems to threaten poultry production and neither vaccines nor treatment tools are now available for ALV prevention and control, periodical molecular monitoring with whole genome sequence and analysis for the circulating strains with ethical eradication of the positive birds are recommended to overcome such a problem. [ABSTRACT FROM AUTHOR]