2011 YÜksek lisans tez özetleri

A Diagnostic Study of Experimentaly Induced Lactococcosis in Rainbow Trout (Oncorhynchus mykiss, W.) by Bacteriological and Serological Techniques

This study was carried out in young rainbow trouts (Oncorhynchus mykiss, W.) experimentally infected with local and reference Lactococcus garvieae strains to diagnose lactococcosis by bacteriological and serological tecniques and to confirm by histopathology. For this purpose, conventional bacteriological diagnostic methods and rapid diagnostic kits, slide agglutination, Indirect Fluorescent Antibody Technique (IFAT) and Enzyme-Linked Immunosorbent Assay (ELISA) tests and histological methods were used.

In this study, young 100 rainbow trouts weighing 65 ± 5 gr obtained from Istanbul University Sapanca Freshwater Fish Production Research and Applied Unit were replaced into adaptation tanks belonging Diseases Section of Aquaculture Department and were adapted for a period of 7 days. Six randomly selected fish from adaption tanks was autopsied then bacteriological inoculation from liver, kidney and spleen were streaked onto TSA medium for bacteriological control. Seventy five healty fish were divided into 3 group and each 25 rainbow trouts were placed into 3 circular fiberglass tanks, 1 m in diameter and 70 cm depth. The first experimental group fish were injected with 10⁷ cells/ml of local L. garvieae strain, second experimental group fish were injected with 10⁷ cells/ml of reference L. garvieae strain also third control group including 20 fish were injected with 0.1 ml sterile PBS. The temperature of water in the tanks was adjusted at 17 ± 1 Cº during the experiment period.

On the fifth day of injection, both group of experimentally infected rainbow trout were showed lethargy and loss of appetite. After the fifth day, externally bilateral exophthalmia with haemorrhagie and corneal opacification, darkening of the skin and haemorrhages at the base of fins and internally extensive haemorrhages in the gut wall, swim bladder and visceral adipose tissue, pale liver with petechial haemorrhagie and enlarged spleen were observed.

Histopathologically, in the expermental groups liquefactive necrosis and reduced of interrenal haemopoietic tissue in the spleen and kidney; liquefactive necrosis in the liver; in the gill filaments hemorrhagie, telangiectasis and hyperplasia of the gill filament; sub-retinal haemorrhagie in the eyes were observed. Gram positive bacteria were present in the lamina propria of intestine stained with Tissue Gram.

The antibody formation against two strains of L. garvieae has been demonstrated in the infected blood serum by the slide agglutination, IFAT and ELISA tests. While strong agglutination were observed in the blodd serum obtained on the fourth week of injection by slide agglutination test, the pathogen bacteria were demonstrated in the eye, spleen, kidney and liver of the moribund fish by IFAT from after fifth day of injection. The presence of spesific antibody in the blood serum were demonstrated by slide agglutination, IFAT and ELISA test from moribund fish four week after injection.

As a result, lactococcosis was diagnosed using by namely as slide agglutination, IFAT and ELISA. This serological tecniques have been performed in a short time when compared with conventional bacteriologic metods.

KÖSE İrem

Danışman : Doç. Dr. Mustafa YILDIZ

Anabilim Dalı : Su Ürünleri Yetişticiliği

Programı : Yetiştiricilik

Mezuniyet Yılı : 2011

Tez Savunma Jürisi : Doç. Dr. Mustafa YILDIZ

Prof. Dr. Metin TİMUR

Prof. Dr. Özkan ÖZDEN

Yrd. Doç. Dr. Erdoğan GÜVEN

Yrd. Doç. Dr. Ferhat ÇAĞILTAY