T. SURESHSHIVAKUMAR2023-12-282023-12-282022https://krishikosh.egranth.ac.in/handle/1/5810204783Diseases are of great concern in fish production and its expansion. Similar to other animals, fish can also suffer from different diseases. Disease is a main agent affecting fish mortality and a major constraint in aquaculture. The global economic loss caused by diseases is about 6.5 billion USD (2017). The habitat of the fish makes it more susceptible to the pathogens. Emerging and re-emerging viral diseases like ISKNV, RSIV, KHV, VNN, SDDV, TRBIV and LCDV are known to cause huge economical loss in wild and cultured. Although prevalence of more than 125 different viruses have been reported in fish culture around the globe including many Asian countries. In the present study, several ornamental and cultured fishes were screened for the viruses of family Iridoviridae and Alloherpesviridae. Moribund and clinically unhealthy samples were collected from different location of Karnataka and were checked for viral infection by using specific primers through conventional PCR method. A total of 130 samples were collected, among them 1 Gold gourami was found to be positive for the presence of ISKNV and 4 Asian Sea bass were positive for RSIV. Further confirmation was done by sequence analysis of positive samples, where sequenced ISKNV strain was more similar (99.74 - 99.88 %) to the Malaysia and Australian ISKNV strains and RSIV strains were more similar (98.77-99.65 %) to Indian and Japanese RSIV strains. Phylogenetic trees of ISKNV and RSIV revealed that our ISKNV strain and RSIV strains formed a clade with the reference ISKNV and RSIV strains. These results suggested, that the occurrence of iridoviral infection is more than the viruses of family Alloherpesviridae in ornamental and cultured fishes in Karnataka.EnglishThesis