Repeated isolation of virulent Newcastle disease viruses of sub-genotype VIId from backyard chickens in Bulgaria and Ukraine between 2002 and 2013

Authors: DIMITROV, KIRIL - Consultant; BOLOTIN, VITALIY - National Scientific Center; MUZYKA, DENIS - National Scientific Center; GORAICHUK, IRYNA - National Scientific Center; SOLODIANKIN, OLEXII - National Scientific Center; GERILOVYCH, ANTON - National Scientific Center; STEGNIY, BORYS - National Scientific Center; GOUJGOULOVA, GABRIELA - National Diagnostic And Research Veterinary Medicine Institute; SILKO, NIKITA - State Research Of Virology And Biotechnology (VECTOR INSTITUTE); Pantin Jackwood, Mary; Miller, Patti; Afonso, Claudio

Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2016
Publication Date: 8/31/2016
Publication URL: https://handle.nal.usda.gov/10113/63171
Citation: Dimitrov, K.M., Bolotin, V., Muzyka, D., Goraichuk, I., Solodiankin, O., Gerilovych, A., Stegniy, B., Goujgoulova, G., Silko, N., Pantin Jackwood, M.J., Miller, P.J., Afonso, C.L. 2016. Repeated isolation of virulent Newcastle disease viruses of sub-genotype VIId from backyard chickens in Bulgaria and Ukraine between 2002 and 2013. Archives of Virology. 161:3345-3353. doi:10.1007/s00705-016-3033-2.

Interpretive Summary: Virulent strains of Newcastle disease virus (NDV)cause significant disease in non-vaccinated and in poorly vaccinated poultry. The circulation of the virulent viruses across the globe represents a constant threat to US poultry industries. In Eastern Europe backyard poultry farming is very common and in the vast majority of cases the birds are not vaccinated against infectious diseases. Therefore, backyard poultry birds, which are highly susceptible to infection with virulent NDV, could play a role on the spread of new genetic variants of this pathogen into Europe. Here we provide a study of the circulating virulent NDV viruses in backyard population in Bulgaria and Ukraine between 2003 and 2013. We have performed virological and molecular characterization of 21 isolates. We have performed first complete fusion protein gene sequencing of NDV isolates from Bulgaria and Ukraine. Our findings show the capability of the virus for long distance dissemination and also prolonged local circulation after initial introduction.

Technical Abstract: Here, we report the circulation of highly related virulent Newcastle disease viruses (NDV) in Bulgaria and Ukraine from 2002 until 2013. All of these NDV isolates have the same virulence-associated cleavage site (‘‘113RQKR;F117’’), and selected ones have intracerebral pathogenicity index values ranging from 1.61 to 1.96. These isolates are most closely related to viruses circulating in Eastern Europe, followed by viruses isolated in Asia during the same period of time. Interestingly, the majority of the viruses were isolated from backyard poultry, suggesting the possibility of a ‘‘domestic’’ or ‘‘urban’’ cycle of maintenance. The molecular characterization of the nucleotide sequence of the complete fusion protein gene of the studied viruses suggests continued circulation of virulent NDV of sub-genotype VIId in Eastern Europe, with occasional introductions from Asia. Furthermore, the high level of genetic similarity among those isolates suggests that the NDV isolates of sub-genotype VIId from Bulgaria and Ukraine may have been part of a broader epizootic process in Eastern Europe rather than separate introductions from Asia or Africa. The continuous monitoring of backyard poultry flocks for the presence of circulating virulent NDV strains will allow early identification of Newcastle disease outbreaks.