الفهرس 
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Abstract
The major diseases affecting sea bass farming are the bacterial diseases vibriosis. V. alginolyticus is one of the most common pathogenic marine Vibrio species and has been found to not only cause serious vibriosis in marine aquatic animals . The marine bacterium V. anguillarum is the causative agent of vibriosis, a systemic disease of fish characterized by acute hemorrhagic septicemia.
Chemotherapy with antibiotics or other veterinary drugs is far from satisfactory because of the appearance of antibiotic-resistant strains. Effective vaccines have been successfully applied in various farmed fish to prevent vibriosis outbreaks caused by a variety of Vibrio spp. Vaccination also influences trafficking of immune cells between hemopoietic organs and blood and metabolic parameters such as hematocrit and serum protein levels.
However, there is as yet no specific vaccine available against V. alginolyticus and L. anguillarum and cross protection between them. Therefore, the main objectives of the present study were: To develop and compare the efficacies of Formalin killed bacterin (FKB) administration by various routes against V. alginolyticus and L. anguillarum in sea bass.
1) In our study, a total number of One hundred of naturally infected sea bass with an average body weight 350 ± 40 g were collected during summer season from private fish farm at Wadi-Mariut region in Borg El-Arab at west Alexandria governorate, Egypt. Fish suffered from mass mortalities and show clinical signs. The freshly dead fish specimens were subjected to clinical, postmortem, and bacteriological examination for isolation of Vibrio spp.
2) After culture on media and biochemical reactions and phenotypic characterizations of V. alginolyticus and L. anguillarium isolates by MALDI-TOF-MS Spectrometry analysis.
3) The incidence of bacterial isolates in the internal organs of all naturally examined fish species (Liver, Spleen, Heart and Kidney) has been studied .
The results revealed that :
1) Clinical signs of V. alginolyticus and L. anguillarium in naturally infected sea bass D. labrax L showed severe hemorrhagic ulceration on abdomen and caudal peduncle and severe hemorrhagic ulceration on the head while in case of L. anguillarium showing hemorrhagic ulceration on abdomen and eye opacity.
2) The post-mortem (PM) lesions of L. anguillarium and V. alginolyticus on the naturally infected sea bass indicated severe liver discolorations, enlarged cherry red spleen, and severe congestion of the internal organs.
3) The prevalence of V. alginolyticus and L. anguillarium retrieved from different organs of naturally infected sea bass revealed that the high incidence of V. alginolyticus and L. anguillarium was in gills followed by the liver then heart and the lowest incidence occurs in spleen and kidney respectively.
4) The histopathological lesion of liver of naturally infected seabass with V. alginolyticus and L. anguillarium showing vaculation and eosinophilic infiltrations in hepatopancreas; fatty degeneration of hepatocytes; marked lymphocytic infiltrations; eosinophilic granular cells in hepatopancreas and vacuolation of hepatocytes.