NEWCASTLE DISEASE EPIDEMIOLOGY, PATHOGENESIS, AND CONTROL
Location: Exotic and Emerging Avian Viral Diseases Research Unit
Title: Neurovirulent pathotype of Newcastle disease virus associated with the reduced capacity of NDV to replicate in vivo and in vitro
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 16, 2011
Publication Date: May 15, 2011
Citation: Susta, L., Miller, P.J., Hu, S., Liu, X., Rue, C.A., Afonso, C.L., Brown, C.C. 2011. Neurovirulent pathotype of Newcastle disease virus associated with the reduced capacity of NDV to replicate in vivo and in vitro [abstract]. 1st International Avian Respiratory Disease Converence, May 15-18, 2011, Athens, Georgia. p. 58.
Reverse genetics was used to create two recombinant Newcastle disease viruses derived from a velogenic viscerotropic NDV strain from China, wild type ZJI (wt-ZJ1). One of the recombinant viruses (rZJ1) was identical to the wild type and the other had the gene for the green fluorescent protein (GFP) inserted between the matrix (M) and phosphoprotein (P) genes (rZJ1-GFP). Growth characteristics were assessed in vitro on DF1 cells by multi-cycle growth curves, and the ability to cause clinical disease was investigated in vivo by the intracerebral pathogenicity index (ICPI) in one-day-old chickens and by detailed pathogenesis studies in 4-week-old naïve Leghorn chickens. The results showed that the insertion of GFP into the r ZJ1 (rZJ1-GFP) genome caused a delay in viral replication in vitro, and slightly decreased pathogenicity, as revealed by ICPI scores (1.89 rZJ1vs 1.62 rZJ1-GFP). In 4-week-old chickens, rZJ1 behaved as a typical velogenic viscerotropic strain, however, animals infected with rZJ1-GFP survived slightly longer and had severe neurological disease, with all infected animals having paresis and paralysis. The neurological signs observed in rZJ1-GFP were identical to those observed in typical velogenic neurotropic pathotypes, suggesting that the capacity to cause neurological damage was present in the velogenic viscerotropic rZJ1, but this aspect was not expressed because of the early death of the birds.