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Subject: Fish Health ×

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    ThesisItemOpen Access
    IMMUNE GENES EXPRESSION IN ORNAMENTAL FISH AGAINST INFECTIOUS SPLEEN AND KIDNEY NECROSIS VIRUS (ISKNV) INFECTION
    (KARNATAKA VETERINARY, ANIMAL & FISHERIES SCIENCES UNIVERSITY, BIDAR, 2021) DHEERAJ, S. B.,; S.K.GIRISHA
    Ornamental sector in fisheries is one of the important growing sectors in the world. Movement of innumerable exotic ornamental fishes paved the spread of various potent infectious viral diseases. Among these viral diseases, recent incidence of Infectious spleen and kidney necrosis virus (ISKNV) belonging to the genus Megalocytivirus has imposed a major threat to many ornamental fishes in India. In the present study, screening of ornamental fishes for ISKNV infection aided to identify the incidence of the virus in various species of ornamental fishes. The obtained ISKNV isolates showed 98.40%-98.76% nucleotide similarity with the MCP gene of ISKNV reference strains (NCBI genbank). Further, the phylogenetic tree constructed by using the sequences of the MCP gene clustered together with the same clade of ISKNV from the NCBI reference strains indicating that the positive samples belong to ISKNV. To understand the host pathogen interaction of ISKNV and ornamental fishes, different immune genes expression profile against ISKNV infection was performed in zebrafish as a model. This is the first kind of the study from India. A total of 14 immune related genes were selected and their relative expression was compared with the PBS control. Major immune related genes like type I interferons (T1-IFN), interferon regulatory factor 3 (IRF3) and tumour necrosis factor (TNFα) were highly expressed during the initial hours of the experiment. Interferon induced antiviral genes like myxovirus A (MxA) and viperin 1 (Vig1) genes were slowly upregulated and reached a maximum during 24-72hpi. Other genes related to adaptive immunity viz., CD4, CD8a, MHC I and IgM were lately expressed when compared with the innate immune genes. The major expression levels were observed in spleen, kidney and liver of ISKNV infected zebrafish. This study indicates, the ISKNV infection imparts a severe damage to organs like spleen, kidney and liver and considered as the target organs for ISKNV infection
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    ThesisItemOpen Access
    ASSESSMENT OF AEROMONAS HYDROPHILA BIOFILM AS ORAL VACCINE CANDIDATE AGAINST AEROMONAS INFECTION IN NILE TILAPIA (OREOCHROMIS NILOTICUS)
    (KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR, 2021) CHANDAN, D.V.,; K.S.RAMESH
    Nile tilapia being one of the most potential candidate species for aquaculture stands second in global total fish production. Along with the increased production, intensification of fish culture systems paved the foundation for the incidence of several infectious diseases. Further, these diseases resulted in the huge economic losses to the fish farmers. Among these diseases, Aeromonas hydrophila is the major causative agent and its outbreaks are most common in fresh water fishes. Hence, for treating this disease, antibiotics were predominately used. Due to the increased usage of antibiotics, raised antibiotic resistance in bacteria were found. To cut such complications biofilm vaccines were used. Biofilm of A. hydrophila oral vaccination was used in Nile tilapia fingerlings to evaluate the effect on growth and disease resistance to A. hydrophila. An experimental trail was conducted for 80 days with biofilm, free cell and control diet. Initial 20 days of the experiment was fed with vaccinated feed (Biofilm and Free cell) and remaining 60 days were fed with control diet. At the end of the study, the biofilm vaccinated group showed significantly higher (p < 0.05) SGR, mean weight gain, ADG and PER. When compared with the free cell vaccinated and control groups, the biofilm vaccinated group showed a lower FCR value. Biofilm vaccinated group of fish showed higher RPS (100, 100 and 87.5%) than free cell vaccinated group of fish (16, 27 and 27%) in case of A. hydrophila, A. sobria and A, veronii respectively. The present study concludes that, the biofilm vaccine of A. hydrophila protects the fish against Aeromonas infections caused by A. veronii and A. sobria. Hence, biofilm vaccines proved to have broad spectrum of defence against Aeromonas infections.