Abstract
Background: Koi Herpesvirus (KHV) infection evidently gave a serious impact to the ornamental fish industry in Indonesia. Measures have been managed to control the outbreak in local fisheries, however, the infection is somehow persistent due to presumptive broad contamination to native fishes, water body, and poor fishpond management. This study investigated the KHV infection cases occurrence in Malang and Batu city based on pathological changes found in deceased fish followed by partial thymidine kinase (TK) encoding gene analysis. Methods: Five and two koi fish were dissected to obtain gill tissue and preserved in non-buffered 10% formalin for histopathologic examination. Two gill tissues were performed polymerase chain reaction (PCR) and an amplicon with prominent specific band were sequenced using Sanger sequencing method. Results: The smaller fish presented lesser gills necrosis with multifocal whitish fibrinous exudate plaques and the larger fish tended to develop a vast area of necrosis. The amplicons partially covered about 410 base pairs (bp) of nucleotides of the total about 998 bp length nucleotides of TK encoding gene that matched to KHV 3 TK encoding gene sequences from NCBI Genbank. Conclusions: There was no distinct grouping of haplotypes based on KHV TK encoding gene sequences.
Keywords: Haplotype, Histopathology, Koi herpesvirus, Phylogeny, Thymidine kinase