|MOURA, VERIDIANA - Federal University Of Goias|
|SUSTA, LEONARDO - Former ARS Employee|
|CARDENAS-GARCIA, STIVALIS - University Of Georgia|
|STANTON, JAMES - University Of Georgia|
|BROWN, CORRIE - University Of Georgia|
Submitted to: Veterinary Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2015
Publication Date: 9/22/2015
Citation: Moura, V., Susta, L., Cardenas-Garcia, S., Stanton, J., Miller, P.J., Afonso, C.L., Brown, C. 2015. Neuropathogenic capacity of lentogenic, mesogenic, and velogenic Newcastle disease virus strains in day-old chickens. Veterinary Pathology. doi: 10.1177/0300985815600504.
Interpretive Summary: Virulent Newcastle disease viruses isolated in poultry in recent years have increased host range and increased pathogenesis in comparison to classical challenge viruses and viruses isolated in the 40s and 50s in the U.S. Newcastle disease virus (NDV) of high virulence are rapidly spreading through Asia and the Middle East, causing outbreaks of Newcastle disease (ND) that are characterized by significant illness and mortality in vaccinated poultry. These viruses cause significant neurological signs and represent a significant threat to the U.S. In order to better control the disease, it is important to understand the mechanisms of pathogenesis. Here we have developed a method to compare the capacity of different types of Newcastle disease viruses, to replicate in the brain of infected chickens, and identified differences in the rate of replication among them.
Technical Abstract: Strains of Newcastle disease virus (NDV) have different abilities to elicit neurological signs in infected birds. Although neuropathogenesis has been characterized in classical animal experiments, there is no specific “in vivo” method to study the intrinsic capacity of NDV strains to infect the brain. In order to determine the capacity of different NDV strains to cause neuropathogenesis independently of their peripheral replication, we inoculated seven NDV strains of different virulence (velogenic, mesogenic, lentogenic) directly into the subdural space in groups of day-old chicks. This method is performed for the intracerebral pathogenicity index (ICPI) test, which is the internationally recognized gold standard to assess NDV virulence. Velogenic strains induced severe lesions and extensively replicated in the nervous tissue by day 2 post-infection (pi), when all infected birds died. Pathogenesis of mesogenic strains was slightly delayed compared to velogenic strains, with similar lesions, virus replication, and death pattern at day 3 and 4 pi. The lentogenic NDV strain did not cause death of infected birds, and there was minimal virus replication, which was limited to the epithelium of the ependyma and choroid plexuses. Results show that extensive NDV replication in the brain is typical of both velogenic and mesogenic, but not lentogenic NDV strains. In addition, this study suggests that differences in the rate of NDV replication in nervous tissue, but not differences in neurotropism, differentiate velogenic from mesogenic NDV strains. This study indicates that intracerebral inoculation might be used as an effective method to study NDV neuropathogenesis.