Megha Kadam Bedekar
Central Food Technological Research Institute, India
Title: Comparative study of two antigens of Edwardsiella tarda as DNA vaccine candidates in Labeo rohita
Biography
Biography: Megha Kadam Bedekar
Abstract
Edwardsiella tarda is an important pathogen of fish globally. This pathogen is also important from a public health point of view, as this is known to produce disease in reptiles, birds, humans and other mammals. In spite of these facts, there is no established successful commercial treatment or preventive measure available. Labeo rohita which is not just an Indian major carp but is also an important part of Indian economy is one of the sufferers of Edwardsiellosis. There is a heavy quality loss in L. rohita because of this bacterial infection. Our laboratory is working on developing a DNA based vaccine against this pathogen. With this aim in present study we compared vaccine potential of two important antigens of Edwardsiella tarda as DNA construct in Labeo rohita fingerlings. L. rohita fingerlings were DNA immunized with recombinant glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and Outer Membrane Protein (OMP-S) genes of E. tarda. PCR primers were designed for both the gene using NCBI GenBank sequences. Amplified genes were cloned in eukaryotic expression vector pIRES 6.5 and purified. Two different groups of L. rohita fingerlings were immunized with 10 µg of respective DNA construct followed by booster at 14 day post vaccination. At 35th day, both the groups were challenged pathogenic E. tarda culture available in our laboratory. Relative percentage survivability, antibody titre, cell mediated immune response and immune gene expression analysis was done. We recorded that RPS was significantly higher in GAPDH group (73%) compared to OMP-S group (62 %). Competitive ELISA test indicated higher antibody titre in OMP-S group than GAPDH group. However nonspecific indicators NBT and phagocytic assay were significantly higher in GAPDH group. iNOS, Ilβ1 and IFNγ gene which are key regulators of immune mechanism were significantly up regulated in GAPDH group compared to OMP-S group. Our study suggested that GAPDH gene can be an ideal candidate for DNA immunization against E. tarda in L. rohita. But the antibody response generated is higher if we use OMP-S.