Molecular characterization of "Candidatus Parilichlamydia carangidicola," a novel Chlamydia-Like epitheliocystis agent in yellowtail kingfish, Seriola lalandi (Valenciennes), and the proposal of a new family, "Candidatus Parilichlamydiaceae" fam. nov. (order Chlamydiales)

• Published in: Applied and Environmental Microbiology
• Main Authors: Stride, M C, Polkinghorne, A, Miller, T L, Groff, J M, LaPatra, S E, Nowaka, B F
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 2013
• Subjects: FoR 0608 (Zoology); 16S rRNA; 16S rRNA sequences; Arctic charrs; Atlantic salmon; cytoplasmic vacuolization; epithelial cells; molecular characterization; morphological features; phylogenetic analysis; rRNA sequences; South Australia; RNA; transmission electron microscopy; Arctic; Arctic charr
• Online Access: https://doi.org/10.1128/AEM.02899-12

Three cohorts of farmed yellowtail kingfish (Seriola lalandi) from South Australia were examined for Chlamydia-like organisms associated with epitheliocystis. To characterize the bacteria, 38 gill samples were processed for histopathology, electron microscopy, and 16S rRNA amplification, sequencing, and phylogenetic analysis. Microscopically, the presence of membrane-enclosed cysts was observed within the gill lamellae. Also observed was hyperplasia of the epithelial cells with cytoplasmic vacuolization and fusion of the gill lamellae. Transmission electron microscopy revealed morphological features of the reticulate and intermediate bodies typical of members of the order Chlamydiales. A novel 1,393-bp 16S chlamydial rRNA sequence was amplified from gill DNA extracted from fish in all cohorts over a 3-year period that corresponded to the 16S rRNA sequence amplified directly from laser-dissected cysts. This sequence was only 87% similar to the reported "Candidatus Piscichlamydia salmonis" (AY462244) from Atlantic salmon and Arctic charr. Phylogenetic analysis of this sequence against 35 Chlamydia and Chlamydialike bacteria revealed that this novel bacterium belongs to an undescribed family lineage in the order Chlamydiales. Based on these observations, we propose this bacterium of yellowtail kingfish be known as "Candidatus Parilichlamydia carangidicola" and that the new family be known as "Candidatus Parilichlamydiaceae". © 2013, American Society for Microbiology.