Study On The Immune Efficacy Of Recombinat Fowlpox Virus And The DNA Vaccine Of ILTV In Chickens

Infectious laryngotractheitis (ILT) is an important upper respiratory tract infection of chickens characterized by signs of respiratory depression, gasping, expectoration of bloody mucus, and high mortality. The disease is found worldwide and may result in severe production losses and reduced egg production. It was classified type B infectious disease by OIE. The causative agent of the disease is an alphaherpesvirus, infectious laryngotracheitis virus (ILTV) that was classified as gallid herpesvirus 1. ILT was also found in our country on the 60's and occurred in many provinces and cities one after another. Present vaccines for ILT are all conventionally attenuated live vaccines. As immunogenicity of ILTV is usually correlated with its virulence, almost all applied vaccines remained moderately pathogenic and have shown a variety of side effects including spread of vaccine virus to nonvaccinates, occurrence of long term "carrier" birds, increasing virulence during in vivo passage, and can't differentiate the vaccine strain and the field strain. With the development of molecular biology, preventing and eliminating ILT with genetic vaccine is the prefered method. At the present time, the recombinant vaccine and DNA vaccine has many advantage ,many protective antigen genes of poultry and animal virus have been expressed with them successfully and some of them can induce protective immunity after being vaccinated animal. In this report, we constructed the recombinant fowl poxvirus expressing the major antigen epitope genes of glycoprotein B and glycoprotein D of ILTV Yantai strain;and DNA vaccine including ILTV gB gene, then evaluated the- abilities of these recombinant virus to protect chickens against challenge by virulent ILTV. This study includes:1. Cloning, sequencing glycoprotein B (gB) gene of infectious laryngotracheitis virus Yantai strain and construction of DNA vaccineThe glycoprotein B gene of ILTV was amplified by polymerase chain reaction(PCR) with extracted total DNA from ILTV Yantai strain as template,and was cloned into...