Project 3.2.3: Use of HVT Vector Vaccines to Protect Against Important Respiratory and Immunosuppressive Diseases of Poultry
PI: Blanca Lupiani and Sanjay M. Reddy
HVT vector vaccines will be generated by insertion of antigenic genes from IBDV, NDV and IBV into the HVT-BAC genome (into the two genomic sites previously identified) by the two-step Red recombination technique.
(a)Testing of regulatory sequences: Genes for the different immunogenic proteins will be cloned under the control of different eukaryotic promoters and bovine growth hormone polyA signal sequences.
(b)Genes will be cloned in both loci and in different combinations to better identify the configuration that provides the best expression of the different proteins.
Evaluation of the stability of recombinant viruses with respect to sites/regulatory sequences.
(a)Expression of foreign proteins (antigenic proteins from IBDV, NDV and IBV) will be examined by immunofluorescence assay (IFA) and ELISA in CEF.
(b)Growth properties of the recombinant viruses compared to parental HVT BAC generated virus will be characterized by multi-step growth kinetics in CEF.
(c)Stability of recombinant viruses by serial passage in cell culture.
Construction of recombinant vaccines
(a)Based on the information obtained during Years 1 and 2 the following recombinant viruses will be generated:
In vitro characterization of recombinant vaccine viruses
(a)Growth properties of the recombinant viruses compared to parental HVT BAC generated virus will be characterized by multi-step growth kinetics in CEF.
(b)In vitro stability of recombinant viruses by serial passage in cell culture.
In vivo characterization of the recombinant viruses.
(a)Characterization of recombinant viruses will be performed by in ovo (18 day of embryonation) and at hatch inoculation with the different vaccines.
(i)Expression of the immunogenic proteins will be determined by examining levels of antibody production against the immunogenic proteins overtime using ELISA.
(b)Protection efficacy of the HVT vector vaccines
(c)Protection of recombinant HVT vaccines will be examined by in ovo or at hatch vaccination with those vaccines that induce the best immune response followed by challenge with pathogenic viruses.
(d)Power analysis and effect size will be used to determine the appropriate number of chickens used for each vaccine being tested.
Upon completion of this project, we will have developed several HVT vector vaccines that protect not only against Marek’s disease but also against other important immunesuppressive (IBD) and respiratory (ND and IB) viral infections. We anticipate that these new vaccines will address and overcome some of the problems associated with currently available vaccines.