BACKGROUND: Enhancement of the immune system seems to be the most promising method of preventing fish diseases and increasing growth rate. Objectives: The purpose of the present study was to investigate the influence of dietary administration of Zataria multiflora Boiss and Menthapulegium L extracts on phagocytosis, lysozyme, respiratory burst and total white and red blood cells (WBC/RBC) of rainbow trout (Oncorhynchus mykiss). Methods: Two hundred and ten fish (100±10 g) were used in a completely randomized design with 7 treatment and 3 replicates in a 2 weeks period (from 0 to 14 d). The basal diet supplemented with 0 (control), 20, 50 and 100 mg/kg food Z. multiflora and M.pulegium extracts. At the end of the experiment (after 14 days), samples from kidney and blood of the fish were collected in order to determine WBC/RBC (by neubauer chamber), serum lysozyme activity (by turbid metric assay, phagocytosic (by number of yeast cells phagocytosed method) and respiratory burst activities (by reduction of nitroblue tetrazolium method) of head kidney tissue. Results: The results indicated that the highest ratio of phagocytosis and respiratory burst activity was observed in 50 mg/kg extract concentration of Z. multiflora (p<0.05). The highest WBC lysozyme activities were seen   in 100 mg/ kg extract concentration of Z. multiflora. No significant difference was shown between RBC in treatment groups and control group (p>0.05). The highest ratio of phagocytosis activity was observed in 100 mg/kg extract concentration of M. pulegium (p<0.05). No significant difference was observed between WBC /RBC, lysozyme, respiratory burst means in treatment groups and control group (p>0.05). Conclusions: It can be concluded that 50 and 100 mg/ kg of the methanol Z. multiflora and 100 mg/ kg M. pulegium have positive effects on stimulating of innate immune system in O.mykiss, but the influence of Z. multiflora extract with100 mg/ kg  concentration is  better than  M. pulegium extract.

BACKGROUND: The repetitive use of antibiotics in different fields (veterinary and medicine) improves the emergence and occurrence of the resistance phenomenon in pathogenic bacteria. Due to the problem of antimicrobial resistance, it is an urgent need to discover new drugs and alternative treatments for the control of bacterial diseases in aquaculture. OBJECTIVES: The purpose of this study is to investigate antibacterial effects of methanol and hexane extracts of medicinal plants Rattles (Prosopis farcta), datura (Datura stramunium L) and milkweed (Calotropis procera L), the major pathogenic bacteria of fish, including Aeromonas hydrophila, Yersinia ruckeri and Streptococcus iniae. METHODS: Extraction was performed using a rotary evaporator. To determine the minimum inhibitory concentration (MIC), the standard microdilution method (Dilution in broth) was used and the minimum bactericidal concentration (MBC) was determined based on MIC values obtained for each extract. RESULTS: The results showed that the effect of most potent extract, methanol extract obtained from fruit rattle on the three studied bacteria, with MIC and MBC are 25, 50mg/ml, respectively. The most sensitive bacteria to methanol and hexane plant extracts, is bacterium Streptococcus iniae and Aeromonas hydrophila and Yersiniaruckeri bacteria were resistant. The studied extracts had stronger antibacterial properties against gram-positive bacteria compared to gram-negative. CONCLUSIONS: According to the results, it seems that the use of methanol extract of Prosopis farcta fruit is effective for treatment of bacterial diseases in aquaculture.

A 474-base pair segment covering the hypervaible region of VP2 gene from six Korean infectious bursal disease virus(K-IBDV) isolates(K1, K2, SH/92, 225, 269, 310) and one attenuated IBDV(DAE) were amplified using RT-PCR, sequenced, and compared with published sequences for IBDV. K-IBDV isolates(K1, K2, SH/92, 225, 269) and foreigh very virulent(vv) IBDV strains had 94.93-100% amino cid sequence similarity. K-IBDV isolate 310 and other K-IBDV isolates had 84.31%-86.07% amino acid sequence similarity. Attenuated strain(DAE), like other attenuated strain, has substitution at positions 279(D to N) and 284(A to T) as well as in the serine-rich heptapeptide region. Five K-IBDV isolates except 310 isolate share unique amino acid residues at positions 222(A), 256(I), 294(I) which are not present in other standard and attenuated strains. At the two hydrophilic region, K-IBDV isolates except 310 isolate had identical amino cids comparing with Belgium vv IVDV 894VB but had four amino acid substitutions comparing with Chinese vv IBDV F9502. The SWSASGS heptapeptide is conserved in all KIBDV isolates. The sequence of K-IBDV isolate 310 was markedly different from other IBDV strains, evolving from a separate lineage than the others. By phylogenetic analysis, Five K-IBDV isolates except 310 isolate were categorized in one group with foreign vv IBDV isolates but K-IBDV isolate 310 was categorized ina separate group which was differentiated form other compared IBDV strains.