Title: Pathologic characterization of genotypes XIV and XVII Newcastle disease viruses and efficacy of classical vaccination on specific pathogen-free birds Authors
|Jones, Megan -|
|Cattoli, Giovanni -|
|Cardenas-Garcia, Stivalis -|
|Brown, Corrie -|
Submitted to: Veterinary Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 10, 2014
Publication Date: February 7, 2014
Citation: Susta, L., Jones, M.E., Cattoli, G., Cardenas-Garcia, S., Miller, P.J., Brown, C.C., Afonso, C.L. 2014. Pathologic characterization of genotypes XIV and XVII Newcastle disease viruses and efficacy of classical vaccination on specific pathogen-free birds. Veterinary Pathology. DOI: 10.1177/0300985814521247. Interpretive Summary: Newcastle disease (ND) is a severe disease of poultry and other avian species, characterized by high morbidity and mortality. It is caused by virulent strains of Newcastle disease virus (NDV), a member of the Paramyxoviride family. In the last few years, NDV strains belonging to a new genotype (XIV) have been described in multiple countries in West Africa. In this work, we characterized by clinico-pathological assessment three strains belonging to the new genotype XIV isolated in Niger, Nigeria and Burkina Faso, and we compared them with a typical genotype VII which has been circulating in South Africa. Results showed that all three genotype XIV strains behaved similarly to the genotype VII representative, and caused very severe hemorrhagic lesions and demise of all infected birds by four days post inoculation. Additionally, vaccination of chickens with common NDV vaccines (QV4 and LaSota) protected chickens from challenge with all four strains. No differences in virus shedding in the environment was observed in vaccinated animals between challenge strains of genotype XIV and VII, suggesting that traditional vaccination plans can be used against this new genotype.
Technical Abstract: To characterize the clinico-pathological characteristics of recently-described genotypes of Newcastle disease virus (NDV), one representative strain of genotype XIV and two of genotype XVII, all isolated from West Africa, were used to infect four-week-old, specific pathogen free (SPF) chickens. The pathobiology of these three strains was compared to a South African NDV strain classified within genotype VII. All chickens infected with the four viruses died or were euthanized by day 4 post-infection due to the severity of clinical signs. Gross and histologic lesions in all infected chickens included extensive necrosis of lymphoid tissues (thymus, spleen, bursa of Fabricius, cecal tonsils, gut-associated lymphoid tissue), gastrointestinal necrosis and hemorrhage, and severe hemorrhagic conjunctivitis. Immunohistochemical staining revealed systemic viral distribution, and the most intense staining was in the lymphoid organs. Results demonstrate that the three West African strains from the previously uncharacterized genotypes XIV and XVII are typical velogenic viscerotropic NDV strains with lesions similar to the South African strain. Under experimental conditions QV4 and LaSota NDV vaccine strains successfully protected chickens from morbidity and mortality against the genotype VII and one genotype XVII NDV strain, with no significant differences in the amount of virus shed when comparing two vaccine schemes used.