RESUMO
Objective: The Newcastle disease virus (NDV) is an infectious disease that causes very high economic losses due to decreased livestock production and poultry deaths. The vaccine's ineffectiveness due to mutation of the genetic structure of the virus impacts obstacles in controlling the disease, especially in some endemic areas. This study aimed to provide an alternative treatment for NDV infection by observing the viral replication inhibitor activity of Clostridium perfringens sialidase in primary chicken embryo fibroblast (CEF) cells. Materials and Methods: The virus was adapted in CEF monolayer cells, then collected thrice using the freeze-thaw method and stored at -20°C for the next step in the challenge procedure. C. perfringens crude sialidase was obtained, but it was further purified via stepwise elution in ion exchange using Q Sepharose® Fast Flow and affinity chromatography with oxamic acid agarose. The purified sialidase was tested for its toxicity, ability to breakdown sialic acid, stopping viral replication, and how treated cells expressed their genes. Results: According to this study, purified C. perfringens sialidase at dosages of 187.5, 93.75, and 46.87 mU effectively hydrolyzes CEF cells' sialic acid and significantly inhibits viral replication on the treated cells. However, sialidase dosages of 375 and 750 mU affected the viability of monolayer CEF cells. Interestingly, downregulation of toll-like receptor (TLR)3 and TLR7 (p < 0.05) in the sialidase-treated group indicates viral endocytosis failure. Conclusions: By stopping endocytosis and viral replication in host cells, sialidase from C. perfringens can be used as an alternative preventive treatment for NDV infection.
RESUMO
BACKGROUND AND AIM: Infectious bronchitis (IB) is still a major problem among poultry industry in Indonesia, IB outbreaks continue to happen even in vaccinated flocks. The emergence of new IB virus (IBV) variants might lead to mismatching between vaccine virus strain and circulating virus strain, this may be a reason of vaccination failure. Information about circulating IBV in a region is important to decide which IB vaccine should be used. However, information about recent IBV strains which circulated in Indonesia and their genetic characters were limited; therefore, the aim of our research was to determine the genetic characterization of S1 gene of IBV isolated from commercial poultry flocks in West Java, Indonesia. MATERIALS AND METHODS: A total of 47 viral isolate samples collected from chickens with clinical sign and reduced in egg production. Six IB live vaccines were used as control, the reference vaccines represent IBV strains including H120, H52, 4/91, CR88, 233A, and 1-96. Primers XCe2+ and XCe2- were used to amplify S1 gene partially. RESULTS: Twenty-six of 47 samples showed positive result to S1 gene of IBV by reverse transcription-polymerase chain reaction. Three IBV isolates, Indonesia/K233A31/18, Indonesia/K4A9/17, and Indonesia/P3/17, were selected for nucleotide sequencing. Phylogenetic analysis of 352 nucleotides of the partial S1 gene shows that isolates Indonesia/K4A9/17 and Indonesia/K233A31/18 have 100% homology with IBV vaccine strain 4/91, while isolate Indonesia/P3/17 has 100% homology with IBV vaccine strain 233A. CONCLUSION: Our result indicates that at least two IBV strains were circulating among poultry in West Java, Indonesia, which is IBV close to vaccine strain 4/91 and 233A. The present study provides updates on the circulating IBV in commercial poultry flocks in West Java, Indonesia, and might use as guidance on selecting a proper IB vaccine strain to improve IB vaccination efficacy in certain region.
