Newcastle disease

Background and Aim: Newcastle disease (ND) is a viral infection that causes high mortality and economic loss in the poultry industry. The Office International des Epizooties (OIE) recommends several diagnostic methods for the detection of ND, including isolation and molecular tests. However, these detection methods are time-consuming and highly expensive. Therefore, this study was conducted to develop a coagglutination kit as a novel diagnostic tool for ND in the poultry industry.

Materials and Methods: Two adult male New Zealand White rabbits weighing 2.5 kg were vaccinated using ND life vaccine intraperitoneally. The vaccination was conducted once a week for 4 weeks with multilevel doses. Rabbits' serum was collected at week 6 and inactivated at 56°C for 30 min. The serum was precipitated using ammonium sulfate and reacted with protein A of Staphylococcus aureus to produce the agglutination kit for detecting ND virus. A total of 25 chickens suspected with ND infection from a local poultry farm in Yogyakarta were used as the test samples. The chickens were necropsied, and the brain, spleen, lung, intestine, and feces were collected. Half of these organs were subjected to tests using the coagglutination kit and reverse transcription-polymerase chain reaction (RT-PCR). The other half was processed for histopathology. Data were analyzed qualitatively.

Results: Of the 25 samples, 13 (52%) were positive for ND infection when tested using both the ND coagglutination kit and RT-PCR. The positive samples also exhibited several histopathological changes, including perivascular cuffing surrounding the cerebral blood-brain barrier, hemorrhagic pneumonia, splenitis, and necrotic hemorrhage enteritis.

Conclusion: This study confirmed that the ND coagglutination kit could be used as a novel diagnostic tool for the detection of ND virus infection in the poultry industry.

Newcastle disease (ND) is a highly contagious disease of chickens causing significant economic losses worldwide. Due to the limitation in their efficacy, current vaccination strategies against ND need improvements. This study aimed to evaluate a new-generation ND vaccine for its efficacy in providing clinical protection and reducing virus shedding after challenge. Broiler chickens were vaccinated in ovo or subcutaneously at hatch with a turkey herpesvirus-based recombinant vaccine (rHVT) expressing a key protective antigen (F glycoprotein) of Newcastle disease virus (NDV). Groups of birds were challenged at 20, 27, and 40 days of age with a genotype V viscerotropic velogenic NDV strain. Protection was 57% and 81%, 100% and 95%, and 100% and 100% after the subsequent challenges in the in ovo and subcutaneously vaccinated chickens, respectively. Humoral immune response to vaccination could be detected from 3-4 wk of age. Challenge virus shedding was lower and gradually decreased over time in the vaccinated birds compared to the unvaccinated control chickens. In spite of the phylogenetic distance between the NDV F gene inserted into the vector vaccine and the challenge virus (genotype I and V, respectively), the rHVT NDV vaccine provided good clinical protection and significantly reduced challenge virus shedding.

One hundred 6-week-old susceptible cockerels were inoculated with a pathogenic strain of infectious bursal disease virus (IBDV) and kept in the same pen as 100 each of 6-week-old pullets, local chickens and broilers. The cockerels developed depression and diarrhoea on day 3 post inoculation (PI) and most of the pullets and some of the local chickens and broilers showed similar signs on day 4 PI. Loss in weight was severe and similar in the pullets and local chickens, being significantly greater than that in the broilers from days 3-11 PI. The total mortality was 85%, 66.7%, 30% and 20% for the pullets, cockerels, local chickens and broilers, respectively. The lesions were more severe in the pullets and local chickens than in the broilers. IBDV antigen and antibody were detected, respectively, in all the bursal and serum samples from the infected chickens tested. The contact exposure method used in this study simulates better what happens in nature than inoculation with IBDV. The red...