Background and Aims: Newcastle disease (ND) is one of the most serious illnesses of chickens. Live vaccines are widely used to prevent chicken from the disease all over the world. Materials and Methods: To access the effective and potentiate ND vaccine, a homogenous subpopulation from LaSota strain was selected following cultivation of the virus on primary chicken embryofibroblast (CEF) cells. Pathogenicity indices and molecular characterization of a several plaques at 3rd passage were analyzed and then the selected clone was candidate for vaccine development. ND vaccine was prepared according to the standard protocols. Results: The immunogenicity of the live vaccine was examined in specific pathogen free (SPF) and commercial chickens. The geometric mean hemagglutination-inhibition (HI) titers induced in chickens vaccinated with the cloned vaccine were not significantly differ than those induced in chickens vaccinated with the similar ND clone vaccine. Conclusion: Efficacy of the ND vaccine was estimated against the virus challenge. The results indicate that the cloned vaccine could confer a complete protection against NDV.

Background and Aims: A multiplex transcription-polymerase chain reaction (m-PCR) was developed for direct detection and discrimination between canarypox virus (CPV) and other avian poxvirus (APV). Materials and Methods: Three compatible primer sets were designed for m-PCR amplification of different loci; fpv126, fpv140, and fpv167 located at highly conserved APV genes. Results: Results showed that m-PCR products of the expected sizes were obtained for all of the primer sets when they were tested either alone or in combination with an artificial mixture of positive controls. Based on the better amplification of fpv167 than other loci, the locus primer set was used to examine tissue samples from canaries clinically diagnosed as AVPinfected. Conclusion: All canary samples were positive for CPV by the m-PCR and virus isolation. The results of the present study indicate the m-PCR assay holds potential to be versatile, rapid, and sensitive for detection of CPV and differentiation of the virus from the other APVs.

Background and Aims: Infectious bursal disease (IBD) is an acute contagious viral disease of birds worldwide. The causative virus induces a persistent immune suppression following destroy B lymphocytes precursors in bursal lymphoid follicles. Vaccination is the main strategy for prevention of the disease in commercial poultry industry. Materials and Methods:To produce a live vaccine against the disease, an new virus strain was isolated from the affected bursa of Fabricius. Diagnostic serological tests, histopathology and molecular examinations were done for pathotyping the isolate. Results:The results indicated that the virus is a new strain and named IBD07IR. In case of developing live IBD vaccine, the bacteriology, purity, titration, reversion to virulence, bursabody index, immunosupression and efficacy tests were performed on the candidate vaccine virus seed. The live vaccine was produced following propagation of the IBDV seed in SPF embryonated eggs. The proper dose of the vaccine was found by administration of SPF chicken groups. Afterward, the laboratory trial was scaled and the clinical trials were done three times with different administration routs. Conclusion: According to serological assays and challenge, the developed live IBD vaccine induces an adequate immunity in both SPF and commercial chickens and had no adverse effects.

Introduction: Poultry vaccines are used to immunize chickens against different diseases. Inactivated vaccines have been widely used to protect poultry against diseases such as infectious bursal disease (IBD). IBD is one of the most important viral immunosuppressive diseases in the poultry industry. This viral disease targets the immune organs. This study was aimed to evaluate the effect of an inactivated IBDV antigen on inducing the humoral immune response in Specific-Pathogen-Free (SPF) chickens. Methods: An infectious strain of bursal disease virus (IBDV) was isolated from an affected chicken bursa of Fabricius. Serological diagnostic tests and molecular experiments were carried out to identify the isolate. Different concentrations of formalin, beta propiolacton (BPL) and binary ethylenimine (BEI) were used for inactivation of IBDV. The samples of IBDV antigen were adjuvanted separately with ISA-70. Threeweek-old SPF chickens were divided into four groups. Groups 1, 2, and 3 received 0.5 ml of the adjuvanted antigens subcutaneously and group 4 received PBS as negative control. Blood samples from each group were collected 4 weeks post-inoculation and the targets were measured by ELISA and serum neutralization test (SNT). Results: The lowest concentrations that could fully inactivate the infectivity of IBD virus were 2.5 mM for BEI, 0.15% for BPL and 0.1% for formalin. Examination of the inactivated samples with 0.1% formalin showed a decrease in antigenicity after 12 months. Treatment with 2.5 mM BEI and 0.15% BPL showed no apparent adverse effect on IBDV infectivity and showed a reliable inactivation. In the SPF chickens of all experimental groups, the antibody titers raised against IBDV were detected by ELISA. Conclusion: In the group which the virus was inactivated using BEI, the antigenicity stability was much better than others. Hence, BEI-inactivated IBDV is suggested for preparing more immunogenic, efficient and stable vaccines against IBD.