29. Sequence of 168 rRNA Gene of Rat Origin CAR Bacillus SMR Strain

Akihiro Kawano Mitsuru NCIIIOI, Satoru Matsushita, Tsuneya Matsumoto, Hiromi Takahashi-Omoe and Kazuei Mita

Keywords: CAR bacillus, sequence similarity, 16S rRNA gene.

Cilia-associated respiratory (CAR) bacillus is an unclassified, gram-negative, filamentous bactertum that was tentatively designated in 1985 as one of the agents that cause chronic respiratory diseases in laboratory rodents. Recently, 16S rRNA gene analysis has indicated that the ratand mouse-ortgnn CAR bacilli were most closely related to members of the Flavobacter/Flexibacter group, while the rabbit origin CAR bacilli were most closely related to members of the genus Helicobacter. In the present study, the 16S rRNA gene of the SMR strain of cilia associated respiratory (CAR) bacillus, which was isolated from a spontaneously infected rat at our unstitute, was sequenced, and its 1,521 nucleotides were determined. On the basis of the results of the homological analysis, it was revealed that the SMR strain was most closely related to Flavobacterium ferrugineum (83% similarity), Chitinophaga pinensis (83%), and Flexibacter sancti (81%) belonging to the Flavobacter/Flexibacter group. This result cotncides with the previous taxonomic analysis of the ratand mouse-origin CAR bacillus. This sequence was compared with the previously determined l6S rRNA gene sequences (rat-origin: the CARB-NIH strain, the CBR strain and the R isolates; mouse-origin: the CBM strain; rabbit-origin: the 13 isofates) of CAR bacillus isolates. Between the SMR and the CARB-NIH strains, the sequence similarity was 99% That is, only a single nucleotide was dif ferent among 1,489 overlapped nucleotides. Therefore, within the accuracy of sequencing technology, we conclude that these two strains, SMR and CARB-NIH, are genetically identical based on the analysis of the 16S rRNA gene. As a result of the comparuson of the 16S rRNA gene sequences of the abovementioned ratand mouse-origin CAR bacillus strains, almost identical sequences were recognized from positions 269 to 454. In the 16S rRNA gene sequence, it is known that there are conserved regtons and variable regions. The former regions are those that are fully conserved over the species and genera in eubacteria, while the latter regions differ between species. Accordingly, it is suggested that posutuons 269 to 454 are peculiar to the ratand mouse-ortgun CAR bacillus, and this region of the gene may therefore be useful in diagnosing ratand mouse-ortgtn CAR bacillus infection by the PCR method.

Publication:
Kawano A. Nenoi, M., Matsushita, S., Matsumoto 'r. ana Muta, K.: t. vet. wea. scz., 62, 797-800, 2000