en Vaccination Vaccination پژوهشي Original research papers <span style="font-size:11pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><a name="_Hlk175808965"><span lang="TR" style="font-size:12.0pt"><span style="line-height:150%"><span new="" roman="" style="font-family:" times="">In this study, effect of <i>lactobacillus delbrueckii bulgaricus (L. bulgaricus)</i>, both in its free form and microencapsulated with alginate/chitosan, on immunity and efficacy of&nbsp; <i>Aeromonas hydrophila</i> vaccine was assessed in common carp. A total of 360 common carp (48&plusmn;5.1 g) were randomly divided in four groups, each in tree replicates. </span></span></span></a></span></span></span></span></span><br> <span style="font-size:11pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><b><span lang="TR" new="" roman="" style="font-family:" times="">*</span></b><b><span lang="TR" new="" roman="" style="font-family:" times="">Corresponding author&rsquo;s email:</span></b>&nbsp; <a href="mailto:alishahim@scu.ac.ir" style="color:blue; text-decoration:underline"><span lang="TR" new="" roman="" style="font-family:" times="">alishahim@scu.ac.ir</span></a><span lang="TR" style="font-family:"Times New Roman",serif"></span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span lang="TR" style="font-size:12.0pt"><span style="line-height:150%"><span new="" roman="" style="font-family:" times="">Groups 1 to 3 were vaccinated against <i>A. hydrophila</i> and fed diets supplemented with basal diet, L.<i> bulgaricus</i>-treated feed, and encapsulated <i>L. bulgaricus</i> -treated feed, respectively, and group 4 was considered as the control.</span></span></span> <span lang="TR" style="font-size:12.0pt"><span style="line-height:150%"><span new="" roman="" style="font-family:" times="">Samples were taken on days zero, 30 and 60 of the experiment. Growth performance indices (including FCR, SGR, PER, and FER) and immunological parameters (antibody titer, serum lysozyme, complement and bactericidal activity, NBT reduction, globulin levels, and myeloperoxidase activity) were evaluated. Additionally, hematological parameters (RBC, WBC, Hb, and Hct), intestinal enzyme activities (lipase, protease, amylase, and ALP), antioxidant status (maladeyaldehide (MDA) levels, superoxide dismutase (SOD), glutathione (GSH), and catalase activity), and serum biochemical indices (glucose, urea, calcium, triglycerides, ALP, CPK, and bilirubin) were compared among the groups. On day 60 of the experiment, the remaining fish in each group were challenged with virulent <i>A. hydrophila</i>, and cumulative mortality was recorded over a 14-day period. The results indicated that group 3 exhibited the highest growth indices and intestinal enzyme activity. Most of the immune parameters showed a significant increase in groups 3 and 2 compared to control group (<i>p</i><0.05). Hematological and biochemical parameters remained consistent across all groups (<i>p</i>>0.05). Following the challenge, the mortality rates were lower in groups 3 (20%) and 2 (30%) compared to control group (60%). Overall, these data exhibited that administration of <i>L. bulgaricus</i> is able to enhance efficacy and immunogenicity of injectable <i>A. hydrophila</i> vaccine. Also, alginate/chitosan-microencapsulation of this probiotic further amplifies its positive effects on the vaccine&#39;s efficacy. </span></span></span></span></span></span></span></span> Aeromonas hydrophila vaccine, Lactobacillus delbrueckii bulgaricus, Common carp, Immunogenicity 35 64 http://ijaah.ir/browse.php?a_code=A-10-148-3&slc_lang=en&sid=1 M.A.K. Aakool mohkaagool@gmail.com 10031947532846003193 10031947532846003193 No Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, M. Alishahi alishahim@scu.ac.ir 10031947532846003194 10031947532846003194 Yes Department of livestock, poultry and aquatic animals Health, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran R. Peyghan peyghan2014@gmail.com 10031947532846003195 10031947532846003195 No Department of livestock, poultry and aquatic animals Health, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran M. Khosravi m.khosravi@scu.ac.ir 10031947532846003196 10031947532846003196 No Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran D. Gharibi d.gharibi@scu.ac.ir 10031947532846003197 10031947532846003197 No Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran