Detection of Kuchijirosho Associated Proteins by Western Blot with Sera of Tiger Puffer which Survived Kuchijirosho

Abstract

ABSTRACT-Kuchijirosho (snout ulcer disease) is an infectious disease of tiger puffer Takifugu rubripes in Japan and Korea. Little is known about detailed characteristics on the causative agent of kuchijirosho, except it is a filterable agent. In the present study, kuchijirosho associated proteins (KAPs) with molecular weight of 100 -120 kDa were detected in brain tissues of tiger puffer by western blot analysis with sera of tiger puffer which survived kuchijirosho, but not in the kidney or spleen tissues. Interestingly, KAPs existed in brain tissues of tiger puffer with no history of kuchijirosho, however, the KAPs were not recognized by those healthy fish sera. KAPs were fractionated in supernatant of brain tissue homogenate containing the kuchijirosho agent by ultra-centrifugation, while pathogenicity of the kuchijirosho agent was observed in the precipitated fraction rather than the supernatant. These results suggest that KAPs are not structural proteins of the kuchijirosho agent, and could be brain tissue proteins antigenically altered by infection of the kuchijirosho agent. It is also considered that the causative agent could be low in antigenicity to host fish because structural proteins of the causative agent was never recognized by host fish sera.

Exogenous RNA Segments Detected Specifically in the Brain of Kuchijirosho (snout ulcer disease)-infected Fugu <i>Takifugu rubripes</i>: Molecular Diagnosis Tool for Kuchijirosho

“…Inouye (1988) indicated that the kuchijirosho virus is a DNA virus because, when a homogenate of kuchijirosho-affected fugu brain was treated with DNase, the infectivity of the pathogen of kuchijirosho was completely lost. Although the symptoms of kuchijirosho caused by infection with kuchijirosho virus used in this study are similar to those described in other reports (Hatai et al, 1983;Nakauchi et al, 1985;Wada et al, 1985Wada et al, , 1986Inoue et al, 1986Inoue et al, , 1992Miyadai et al, 2001;Takami et al, 2007aTakami et al, , 2007bTakami et al, , 2007c, more than one virus species might be involved in the development of kuchijirosho. We detected KARs in fugu showing symptomatic signs similar to kuchijirosho that had broken out at an aquaculture farm in 2020 in Japan (Fig.…”