Molecular identification of Newcastle disease virus isolated on the poultry farm of the Moscow Oblast in summer of 2022

Abstract

In August 2022, a sudden death in backyard chickens was reported in the Moscow Oblast (urban district Chernogolovka, settlement Starki). As a result, within just a few days 45 chickens on this farm died or fell ill with the following signs – gray mucus discharge from nostrils and beak, coughing, gasping and rales. On day 1–3 after the onset of symptoms, the chicken died. The Newcastle disease virus, which is a representative of the Paramyxoviruses family, was isolated from the dead poultry. We determined the nucleotide sequences of fragments in F gene (encodes the fusion surface protein) and in NP gene (encodes the nucleocapsid protein). The motif of 109SGGRRQKRFIG119 proteolysis site, typical for the velogenic pathotype, was determined for the F gene, and a phylogenetic analysis was carried out to demonstrate that the isolate belonged to Subgenotype VII, Class II of the subfamily Avulavirinae. The Basic Local Alignment Search Tool revealed that they are most genetically related with isolates from Iran. It was found that the average death time of developing chicken embryos, infected with a minimum infectious dose, was 52 hours, which is typical for the velogenic pathotype. The virus caused 100% death in six-week-old chickens after oral infection and 100% death in all contact chickens, including those kept in cages at a distance, which proves the high level of pathogenicity and contagiousness of the recovered isolate and its ability to transmit both via fecal-oral and aerosols–borne routes. No death cases were reported in mice after intranasal infection with high doses.

Keywords

• newcastle disease virus
• pathogenicity
• molecular genetic analysis
• contagiousness