title: Effect of phylogenetic diversity of velogenic Newcastle disease virus challenge on virus shedding post homologous and heterologous DNA vaccination in chickens.
abstract: Newcastle disease (ND) is a highly devastating disease for the poultry industry as it causes high economic losses. In this present study, a DNA vaccine containing the F and HN surface antigens of a highly virulent Newcastle disease virus (NDV), NDV/1/Chicken/2005 (FJ939313), was successfully generated. Cell transfection test indicated that the vaccine expressed the F and HN genes in Hep-2 cells. The main objective of this study was to compare the extent of protection induced by DNA vaccination after homologous and heterologous NDV-challenge as determined by the amount of NDV shedding after challenge. NDV-antibody-negative chickens were vaccinated either once, twice or thrice intramuscularly at 7, 14 and 21 days old and were challenged 14 days post vaccination with either homologous virus (vaccine-matched velogenic viscerotropic Newcastle disease virus (vvNDV) strain, FJ939313), phylogenetically related to group VII, or a phylogenetically divergent heterologous virus (unmatched vvNDV strain, AY968809), which belongs to genogroup VI and shows 84.1% nucleotide similarity to the NDV-sequences of the DNA vaccine. Our data indicate that birds, which received a single dose of the DNA vaccine were poorly protected, and only 30-40% of these birds survived after challenge with high virus shedding titre. Multiple administration of the DNA vaccine induced high protection rates of 70-90% with reduced virus shedding compared to the non-vaccinated and challenged birds. Generally, homologous challenge led to reduced tracheal and cloacal shedding compared to the heterologous vvNDV strain. This study provides a promising approach for the control of ND in chickens using DNA vaccines, which are phylogenetically closely related to the circulating field strains.
authors.affiliation: a Department of Clinical Studies, Collage of Veterinary Medicine and Animal Resources , King Faisal University , Al-Hasa , Saudi Arabia.|b Deaprtment of Avian and Rabbit Medicine, Faculty of Veterinary Medicine , Zagazig University , Zagazig , Egypt.
authors.forename: Mahmoud H A
authors.initials: MH
authors.lastname: Mohamed
authors.affiliation: c Veterinary Teaching Hospital, Faculty of Veterinary Medicine , Zagazig University , Zagazig , Egypt.
authors.forename: Adel M
authors.initials: AM
authors.lastname: Abdelaziz
authors.affiliation: d Department of Biosciences and Bioengineering , Indian Institute of Technology Guwahati , Guwahati , Assam , India.
authors.forename: Sachin
authors.initials: S
authors.lastname: Kumar
authors.affiliation: e Executive Department of Risk Assessment , Saudi Food and Drug Authority , Riyadh , Saudi Arabia.
authors.forename: Malik A
authors.initials: MA
authors.lastname: Al-Habib
authors.affiliation: b Deaprtment of Avian and Rabbit Medicine, Faculty of Veterinary Medicine , Zagazig University , Zagazig , Egypt.
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Megahed
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology*; D002642:Chick Embryo; D002645:Chickens / Q000821:virology*; D005260:Female; D005838:Genotype; D008297:Male; D009521:Newcastle Disease / Q000517:prevention & control* / Q000821:virology; D009522:Newcastle disease virus / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D010802:Phylogeny; D011201:Poultry Diseases / Q000517:prevention & control* / Q000821:virology; D013047:Specific Pathogen-Free Organisms; D014611:Vaccination / Q000662:veterinary; D014613:Vaccines, Attenuated; D014760:Viral Fusion Proteins; D014765:Viral Vaccines / Q000276:immunology*; D017201:Virus Shedding
chemical_list: D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014760:Viral Fusion Proteins; D014765:Viral Vaccines
keywords: DNA vaccines; Newcastle disease; challenge; diversity; virus shedding