Humoral and non-specific immune responses in rainbow trout (Oncorhynchus mykiss) naturally exposed to and immunized with Streptococcus iniae

Authors

1 ‌دانش آموخته دانشکده دامپزشکی دانشگاه شیراز

2 ‌بخش بهداشت وبیماریهای آبزیان، دانشکده دامپزشکی دانشگاه شیراز

3 ‌بخش ایمنی شناسی، گروه پاتوبیولوژی، دانشکده دامپزشکی دانشگاه شیراز

4 بهداشت وبیماریهای آبزیان، دانشکده دامپزشکی دانشگاه شهرکرد،

5 تحقیقات واکسن و سرم سازی رازی، منطقه جنوب کشور (شیراز)

Abstract

In this study, immune responses against Streptococcus iniae
infections in rainbow trout (Oncorhynchus mykiss) were analyzed. Anti-streptococcal antibody (ASA) levels, respiratory burst activity (RBA), phagocytic activity (PA) and phagocytic index (P index) were measured in kidney macrophages. Fish were allocated to three experimental groups (n = 50 per group): survivors of natural S. iniae infections, non-exposed healthy fish immunized by immersion with formalin-killed S. iniae bacterin and a control group of non-exposed healthy fish. Blood sera and kidney samples were collected from each group (n = 10 fish) at days 0, 15, 30, 45 and 65 post-immunization (p.i.).
Analysis of ASA levels, RBA, PA and P index in survivors of Streptococcus infections revealed optical density (OD) values of 0.082-0.091, 0.089-0.091, 53-55 and 1.8-1.9 respectively. In the immunized non-exposed group, the ASApeak antibody level occurred at day 15 (mean OD=0.122) and declined significantly by day 65 (p<0.05). Similarly, the mean PAand P index values of macrophages peaked at day 15 p.i. (71 and 3.2, respectively) and declined by day 65(p<0.05). Therefore, the acquired immune status of survivors of naturalS. iniae infection was not altered by immunization.
Iranian Journal of Veterinary Medicine
Volume 5, Issue 4 - Serial Number 666206
13 International Journal Of Veterinary Research
December 2011
Pages 218-224

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