Respiratory and Reproductive Impairment of Commercial Layer Chickens After Experimental Infection with Gallibacterium anatis Biovar haemolytica.

The prevalence of Gallibacterium anatis in poultry production has increased over the last two decades. However, only a few studies have explored the pathogenicity of this bacterium in commercial layer chickens. This trial studied the aspects of the pathogenicity of a Gallibacterium anatis biovar haemolytica local Egyptian isolate (previously registered as strain B14 with GenBank accession no. KJ026147). We used 500 base pairs of a 16S ribosomal RNA gene and the 16S-23S ribosomal RNA intergenic spacer, partial sequence in an experimental infection trial in commercial White Shaver layer chickens aged 19 wk. The hens were divided into three groups of 40 birds each. The hens in Groups 1 and 2 were experimentally infected through the intranasal (IN) and intravenous (IV) routes, respectively, with a dose of 0.2 ml/bird containing 1.2 × 109 colony-forming units/ml. In contrast, Group 3 was kept as a noninfected control group. Both IN and IV infections resulted in a delayed egg laying for 1 wk and a significant (P ≤ 0.05) drop in egg production by 7.81% and 10.28% compared with the control group over 7 wk. Severe lesions in the form of hemorrhagic pneumonia, catarrhal tracheitis, ovarian follicle and oviductal regression, and septicemia were evident on necropsy, demonstrating the pathogenicity of G. anatis as a primary pathogen.

Molecular characterization and phylogenetic analysis of a virulent Marek's disease virus field strain in broiler chickens in Japan.

Marek's disease is a lymphoproliferative disease causing a serious threat in poultry production. Field strains of Marek's disease virus (MDVs) are continuously re-emerging, causing great economical losses to the poultry industry worldwide in spite of the intensive vaccination and restrictive management policy used. Histopathological and molecular characterizations of MDVs are essential for monitoring the changes of viruses and evaluating the effectiveness of existing vaccines. During 2016, 190 visceral tumour tissues representing 30 vaccinated chicken flocks from the Gifu prefecture, Japan, were analysed. A pathological examination revealed the presence of lymphoproliferative lesions in the visceral organs. Polymerase chain reaction screening of tissue specimens using specific primers for avian leucosis virus, reticuloendotheliosis virus, and MDV was positive only for MDV. The polymerase chain reaction products of meq, pp38, virus-induced IL-8 homology, and glycoprotein MDV genes were sequenced and used for homology, phylogenetic, and similarity level analysis with the published reference of MDVs in the database. The results revealed high similarity between the field isolates, vv and vv+ strains of MDV from the USA and China. Several point mutations in the nucleotide sequence of the field isolates and their deduced amino acid sequences were detected in those genes. The present molecular analyses indicated that nucleotide and amino acid changes could be valuable criteria for differentiation and determination of the pathogenicity and oncogenicity of MDVs according to the Avian Disease and Oncology Laboratory pathotyping in vivo studies. Furthermore, the results suggest that development of a new vaccine must be considered to overcome this devastating avian oncogenic viral disease.