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Newcastle disease virus (NDV) is a highly contagious virus infects a wide range of avian species including chicken and ducks. The disease can be fatal for many types of them. It was believed that ducks and geese act as natural reservoirs of NDV because of their natural resistance. Recently, NDV isolates were pathogenic for ducks. Therefore, our study aimed to investigate the pathogenicity of highly pathogenic NDV genotype VII in white Ross commercial broiler chickens and Mallard ducks on the basis of clinical, histological observation and immunohistochemistry findings of virus antigen through studying the sequential pathological lesions of both species at 2nd, 5th and 10th dpi. Both species were inoculated via intranasal route by NDV genotype VII (accession number MT887290). Clinical lesions and mortalities were evident mostly in chickens rather than in ducks. Respiratory, digestive and nervous signs were clearly manifested in chickens. Ducks showed low level of mortalities and the nervous signs were the most obvious symptoms. Microscopic findings of chickens showed severe pancreatitis, pneumonia, enteritis as well as pericarditis and brain malacia. Similar findings were noticed in ducks but with lower degree of severity. Brain lesions in ducks included encephalitis and perivascular reaction mostly within the cerebellar tissue. Immunohistochemistry reaction against NDV antigen showed marked immunostaining within epithelial cells, purkinje cells and inflammatory cells mostly the macrophages. The immunohistochemistry reaction was correlated with the pathological findings in both species. In conclusion, the mortality and lesions of NDV in both species were correlated with systemic alterations associated with pancreatitis, pneumonia and encephalopathy. Moreover, the obtained data revealed possible susceptibility of ducks to NDV genotype VII, which might be need forthcoming viral vaccination strategy for ducks against NDV.

Ochratoxin A (OTA) formation prevention is not usually available so counteracting strategies are urgent. This study investigated the toxic effects of OTA on Nile tilapia with trials to neutralize these effects by using some feed additives. Supplements used as one percent (Garlen Extra4, Nigella sativa, Garlen Extra4 plus Nigella sativa and a commercial mycotoxins binder, Fero Bind Pro) were added to 500 ppb/kg OTA-contaminated diet. Fish were fed at 3% body weight per day for 10 weeks. The clinical signs recorded in OTA – intoxicated positive control group were sluggish swimming and off food before death with reduction in survivability (53%) and growth performance. Several post-mortem lesions were in liver, kidneys and spleen. Serum levels of ALT, AST, creatinine and urea were significantly increased with reduction in total protein, albumin and globulin in ochratoxicated fish group compared to the negative control group. Concerning the pathological changes that have been noticed in ochratoxin treated fish were almost completely alleviated in examined tissues of fish that were fed on diet with Garlen Extra4 plus Nigella sativa or Nigella sativa and partially in fish that were fed on diet with Garlen Extra4 or Fero Bind Pro, respectively. Best detoxifying results were obtained by using 30 g/kg Nigella sativa plus 0.1 g/kg Garlen Extra4 followed by Nigella sativa, Garlen Extra4 then Fero Bind Pro as a commercial Mycotoxins binder. It could be concluded that inclusions of 30 g/kg Nigella sativa plus 0.1 g/kg Garlen Extra4 in Oreochromis niloticus (O. niloticus) diets could partially reduce OTA toxic effects. Keywords: Detoxifying agents, Feed additives, Garlen, Mycotoxins binder, Nigella sativa

Newcastle disease virus (NDV) remains a constant threat to the poultry industry. There is scarce information concerning the pathogenicity and genetic characteristics of the circulating velogenic Newcastle disease virus (NDV) in Egypt. In the present work, NDV was screened from tracheal swabs collected from several broiler chicken farms (N = 12) in Dakahlia Governorate, Egypt. Real-time reverse transcriptase polymerase chain reaction (RRT-PCR) was used for screening of velogenic and mesogenic NDV strains through targeting F gene fragment amplification, followed by sequencing of the resulting PCR products. The identified strain, namely, NDV-CH-EGYPT-F42-DAKAHLIA-2019, was isolated and titrated in the allantoic cavity of 10 day old specific pathogen-free (SPF) embryonated chicken eggs (ECEs), and then their virulence was determined by mean death time (MDT) and intracerebral pathogenicity index (ICPI). The pathogenicity of the identified velogenic NDV strain was also assessed in 28 day old chickens using different inoculation routes as follows: intraocular, choanal slit, intranasal routes, and a combination of both intranasal and intraocular routes. In addition, sera were collected 5 and 10 days post inoculation (pi) for the detection of NDV antibodies by hemagglutination inhibition test (HI), and tissue samples from different organs were collected for histopathological and immunohistochemical examination. A series of different clinical signs and postmortem lesions were recorded with the various routes. Interestingly, histopathology and immunohistochemistry for NDV nucleoprotein displayed widespread systemic distribution. The intensity of viral nucleoprotein immunolabeling was detected within different cells including the epithelial and endothelium lining, as well as macrophages. The onset, distribution, and severity of the observed lesions were remarkably different between various inoculation routes. Collectively, a time-course comparative pathogenesis study of NDV infection demonstrated the role of different routes in the pathogenicity of NDV. The intranasal challenge was associated with a prominent increase in NDV lesions, whereas the choanal slit route was the route least accompanied by severe NDV pathological findings. Clearly, the present findings might be helpful for implementation of proper vaccination strategies against NDV.