Isolation and characterization of class II Newcastle disease from circulating strains in Mizoram, NER, India

Background: Newcastle disease is a highly virulent emerging disease affecting the poultry population irrespective of age, sex, breed and other characteristics. It is a highly mutating virus that is globally widespread and comes under the category of transboundary diseases. Despite strict vaccination practices even in remote areas, this virus causes high mortality (90-100%), leading to huge economic losses in the poultry industry.

Methods: This study focusses on the discovery of the novel vaccine resistant mutants for the elimination of the virulence of the disease among the flocks in Mizoram, which is in the NER, India. Prevalent outbreaks were reported in the Selesih, Zemabawk, Melthum districts of Mizoram from October to December 2021. Clinical signs of Newcastle disease were manifested, and the carcasses were brought to the department. They were eviscerated for clinico-pathological examinations. Representative tissue samples were collected for molecular detection using reverse transcriptase polymerase chain reaction targeting the whole length of Fusion gene (1662 base pairs). Homogenized isolates of the positive samples were sequenced and analyzed phylogenetically.

Results: The results showed that the isolates belonged to the novel genotype XXII of Newcastle disease virus as per the updated nomenclature system of classification. The XXII genotype was subdivided into sub-genotype XXII.1 and sub-genotype XXII.2.

Conclusions: The rapid isolation and identification of the disease was of great importance in the present study due to the emerging nature of the virus.