The present work was designed to study the effect of DEAE-dextran and Magnesium Chloride (MgCl) on fowl pox virus vaccine (FPV) in order to obtain a maximum titer allowing the massive production of the vaccine. Fowl pox virus; used for vaccine production; was propagated on embroynated chicken eggs (ECE) and chicken embryo fibroblast (CEF), the virus was inoculated in ECE and CEF without DEAEdextran nor MgCl, and with DEAE-Dextran and MgCl separately. The time of harvestion was early as one day post inoculation in CEF. The virus titer were higher in case of treated inoculums with DEAEdextran and MgCl reaching (6.2 and 7.5 log 10 TCID 50 /ml respectively) on CEF and (6.2 and 6.7 Log 10 EID 50 respectively) on ECE. Fowl pox vaccines (FPV) were prepared before and after DEAE-Dextran and MgCl treatment. The application of quality control assays revealed the safety, sterility and potency of the prepared vaccines. Immune response of the prepared FPV vaccines were evaluated in chickens using virus neutrization test (VNT). It was found that, the use of DEAE-Dextran and MgCl with the recommended concentrations could result in increasing the virus titer with reduction in the time of harvestation and accordingly increase the vaccine production and decrease its cost.

Infectious Bronchitis Virus (IBV) is considered an important virus which may cause major losses in the poultry industry. One of the most important and effective tool that control the infection spread is the vaccination strategy. The present study was undertaken to determine the antigenic relationship between the currently used IBVs, classic and variant vaccinal strains, and the dominating Egyptian variant-2, IBV which could be relatively reflecting the quality of such vaccine. The recommended doses of the monovalent live IBV vaccines of Ma5, H120, 4/91 & CR88, and bivalent vaccine of H120-D274 were administrated via the eye-drop route in groups of 2-week-old SPF-chickens. Three weeks after vaccination, immunized and control chickens were bled, and serum samples were collected. Sera were tested individually for measuring the IBV-Haemagglutination Inhibiting (HI) antibodies against each of IBV-haemagglutinating antigen prepared from the reference classic M41 strain and the Egyptian variant.2 strain (Egy/12/2b spike protein), and IBV-neutralizing antibodies against the Egyptian variant-2 strain. The chicken groups vaccinated with the commercial live vaccines of strains Ma5, H120, 4/91, CR88 and H120-D274 of IBV respectively developed mean serum HI-antibody titers of 6.8, 6.5, 4.9, 5.0 and 5.5 log 2 with the reference classic strain M41-HA antigen, and 3.0, 3.0, 4.4, 4.0, and 4.6 log 2 with the Egyptian variant.2 strain-HA antigen. However, the obtained results revealed utility of VN test more than HI test for assessment of the antigenic relatedness between the vaccinal and challenge strains of IBV as well as testing quality of different commercial live IBV vaccines using the sera of vaccinated chickens against the field strain(s) matched with the homologous strain(s); the antigenic relatedness (r 1) between the dominating Egyptian variant-2 strain, and the vaccinal strains, CR88, D274-H120 and H120 of IBV were 33%, 55% and 17% respectively.

Chicken anemia virus (CAV) is the causative agent of chicken infectious anemia (CIA). Studying CAV isolates in Egypt and their genetic diversity and its potential role in vaccination failure recently noticed in broiler flocks, is lacking in Egypt. So, the present study aimed to characterize CAV isolate-collected from a commercial broiler flock suffered from severe anemia and high mortality based on sequence and phylogenetic analysis of partial VP1 gene as well as to study pathogenicity and immunosuppressive potential in one day-old SPF chicks. The CAV isolate proved to be positive by PCR. The PCR product was sequenced and submitted to the gene bank under the accession number KX171350 and the CAV strain was designated as CLEVB-Zag2. Phylogenetic analysis at the nucleotide and amino acids level classify CLEVB-Zag2 CAV under group III (genotype III) of CAVs. On the other hand, the CLEVB-Zag2 CAV was found to be highly pathogenic for the experimentally inoculated SPF-chicks showing depression, severe anemia in almost all chicks in two infected groups beginning at the 7th day post infection (PI) and reached the peak of severity at the 14th day (hematocrit value, hemoglobin conc. and RBCs counts) are significantly reduced in chicks of the infected group. Blue wings were observed in few chicks in each infected group at the 14th day PI. Macroscopic lesions consisting of subcutaneous and muscular hemorrhages are observed with pale bone marrow, significant atrophy of thymus, spleen and bursa, hepatomegally with mottled liver and paleness of the carcasses were detected 7 days PI Those findings were evident and increased in severity until the day 14 PI. Concerning the CLEVB-Zag2 CAV, it was found to be highly immunosuppressive in the infected SPFchicks vaccinated with a commercial potent inactivated H5N1 vaccine as manifested by a significant reduction (protection 50%). The variance in the titer of the shieded challenge H5N1 virus was 1.45 log10 and the mean HI titer at the 4th week post vaccination was 1.5 log2 compared with the non-infected vaccinated group where these values were 90%, 2.35 log10 and 5.3 log2; respectively. In conclusion, the present study revealed that the CLEVB-Zag2 CAV isolate is highly pathogenic and immunosuppressive.

No abstract