A Spirochaete is suggested as the causative agent of Akoya oyster disease by metagenomic analysis

作者：Matsuyama Tomomasa^*; Yasuike Motoshige; Fujiwara Atushi; Nakamura Yoji; Takano Tomokazu; Takeuchi Takeshi; Satoh Noriyuki; Adachi Yoshikazu; Tsuchihashi Yasushi; Aoki Hideo; Odawara Kazushi; Iwanaga Shunsuke; Kurita Jun; Kamaishi Takashi; Nakayasu Chihaya

来源：PLos One, 2017, 12(8): e0182280.

DOI：10.1371/journal.pone.0182280

Mass mortality that is acompanied by reddish browning of the soft tissues has been occurring in cultured pearl oyster, Pinctada fucata martensii. The disease is called Akoya oyster disease (AOD). Although spreading pattern of the disease and transmission experiments suggest that the disease is infectious, the causative agent has not yet been identified. We used shotgun and 16S rRNA-based metagenomic analysis to identify genes that are present specifically in affected oysters. The genes found only in diseased oysters were mostly bacterial origin, suggesting that the causative agent was a bacterial pathogen. This hypothesis was supported by the inhibition of AOD development in naive oysters injected with the hemolymph of diseased animals followed immediately with penicillin bath-administration. Further analyses of the hemolymph and mantle specifically and universally detected genes of bacteria that belong to phylum Spirochaetes in diseased pearl oysters but not in healthy oysters. By in situ hybridization or immunostaining, a Brachyspira-like bacterium was observed in the smears of hemolymph from affected oysters, but not from healthy oysters. Phylogenetic analysis using 16S rRNA sequences showed that the presumptive causative bacterium was outside of but most closely related to family Brachyspiraceae. We propose 'Candidatus Maribrachyspira akoyae' gen. nov, sp nov., for this bacterium.

• 出版日期2017-8-3
• 单位上海生物信息技术研究中心