مقالات پذیرفته شده در سومین کنگره بین المللی زیست پزشکی
Flow Cytometric Evaluation of Cellular Immune Responses of SPF Chickens Induced by fowl pox vaccine
Flow Cytometric Evaluation of Cellular Immune Responses of SPF Chickens Induced by fowl pox vaccine
Mohammadrezaazizi,1,*Esmail Asli,2
1. Department of Microbiology, Faculty of Sciences, Islamic Azad University, Karaj, Iran 2. Department of Poultry Research & Diagnostic, Razi Vaccine and Serum Research Institute, AREEO, Karaj, Iran
Introduction: Fowl pox is a disease of chickens and its distribution is world-wide. It is a disease of economic importance in Iran. The disease has an economic impact on the poultry industry, and even the outbreak has been reported in vaccinated herds. The present study provides more information that will assist poultry industry to a better understanding of the fowl-pox problems. This study was designed to evaluate the cellular immune responses of SPF chickens induced by fowl pox (FP) vaccines using flow cytometric method. The immunogenicity of the vaccine was also compared with commercial and Razi live attenuated FP vaccines in Specific pathogen free (SPF) chickens.
Methods: Three groups of certain specific pathogens free (SPF) chickens were (21 days old, n = 40 per group) were used. One group served as the negative control (PBS) and the other two groups were inoculated with either the local FP vaccine or commercial vaccine. Inoculations of All chicks were done by wing-web puncture with a double needle. All chickens were kept for 5 weeks following inoculation. Blood samples from each group were collected from the vein under the wing at weeks 1, 2, 3, 4, 5, and 6 after post-vaccination. Peripheral blood mononuclear cells (PBMC) were isolated from each blood sample using Ficoll–Hypaque density gradient centrifugation. The percentages of CD3+, CD3+ CD4+, and CD3+CD8+ lymphocytes in the PBMC suspension were analyzed by flow cytometry. Figure 1 shows the schematic diagram of the experimental procedures. All flow cytometry analyses were performed on a Partec PAS equipped with a 488 nm blue laser and a 633 nm red. Statistical analysis was used for evaluation of significant difference between the groups and a P < 0.05 was considered to be statistically significant.
Results: The results of this study showed that vaccinated chickens elevated one week later swelling and scab formation (“take”) at the site of vaccination. A maximum elevation of “takes” at day 7 post vaccination (90-100%) were observed. Absence of “take” indicates lack of effectiveness of vaccine or improper vaccination. they were not show any symptoms of disease. vaccinated chickens develop cell-mediated immune responses. Vaccinated chickens from all groups found to be significantly higher frequency of circulating T cells than the control group (Figure 2). Significant increases in CMI responses were observed in inoculated chickens with commercial and local Razi fowl pox vaccines as assessed by flow cytometry method., The ratios of CD4+ to CD8+ lymphocytes in both groups of commercial and local Razi fowl pox vaccinated groups were significantly higher (P < 0.05) than the control group inoculated with PBS from the first week after vaccination (Table 1). the percentages of CD3+, CD3+CD4+, and CD3+CD8+ T-lymphocytes were increased (P < 0.05) in chickens vaccinated with commercial and local Razi fowl pox vaccines. There were no significant differences between both groups of vaccines
Conclusion: The present study revealed that the protective immunity may be associated with increased cellular immunity, which has been interpreted as enhancing the proliferation of T cells and increasing CD4+ to CD8+ ratios due to vaccination of the FP vaccine. This suggests that increased the induction of the immune responses by predominantly a Th1-type response.