title: Assessment of the pathogenicity of cell-culture-adapted Newcastle disease virus strain Komarov.
abstract: Newcastle disease vaccines hitherto in vogue are produced from embryonated chicken eggs. Egg-adapted mesogenic vaccines possess several drawbacks such as paralysis and mortality in 2-week-old chicks and reduced egg production in the egg-laying flock. Owing to these possible drawbacks, we attempted to reduce the vaccine virulence for safe vaccination by adapting the virus in a chicken embryo fibroblast cell culture (CEFCC) system. Eighteen passages were carried out by CEFCC, and the pathogenicity was assessed on the basis of the mean death time, intracerebral pathogenicity index, and intravenous pathogenicity index, at equal passage intervals. Although the reduction in virulence demonstrated with increasing passage levels in CEFCC was encouraging, 20% of the 2-week-old birds showed paralytic symptoms with the virus vaccine from the 18(th)(final) passage. Thus, a tissue-culture-adapted vaccine would demand a few more passages by CEFCC in order to achieve a complete reduction in virulence for use as a safe and effective vaccine, especially among younger chicks. Moreover, it can be safely administered even to unprimed 8-week-old birds.
authors.affiliation: Mumbai Research Centre, Central Institute of Fisheries Technology, Mumbai, India .
authors.forename: Sivam
authors.initials: S
authors.lastname: Visnuvinayagam
authors.affiliation: Veterinary College and Research Institute, Tamil Nadu, India .
authors.forename: K
authors.initials: K
authors.lastname: Thangavel
authors.affiliation: Central Institute of Brackishwater Aquaculture, Tamil Nadu, India .
authors.forename: N
authors.initials: N
authors.lastname: Lalitha
authors.affiliation: Veterinary College, Tamil Nadu, India .
authors.forename: S
authors.initials: S
authors.lastname: Malmarugan
authors.affiliation: Veterinary College and Research Institute, Tamil Nadu, India .
authors.forename: Kuppannan
authors.initials: K
authors.lastname: Sukumar
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens / Q000276:immunology / Q000821:virology*; D009522:Newcastle disease virus / Q000145:classification / Q000254:growth & development / Q000472:pathogenicity*; D011201:Poultry Diseases / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D061251:Primary Cell Culture; D014611:Vaccination; D014613:Vaccines, Attenuated / Q000009:adverse effects / Q000276:immunology / Q000627:therapeutic use*; D014765:Viral Vaccines / Q000009:adverse effects / Q000276:immunology / Q000627:therapeutic use*
chemical_list: D014613:Vaccines, Attenuated; D014765:Viral Vaccines
keywords: Komarov strain; Newcastle disease; Newcastle disease vaccine; chicken embryo fibroblast