BREVINEMA-ANDERSONII GEN-NOV, SP-NOV, AND INFECTIOUS SPIROCHETE ISOLATED FROM THE SHORT-TAILED SHREW (BLARINA-BREVICAUDA) AND THE WHITE-FOOTED MOUSE (PEROMYSCUS-LEUCOPUS)

A spirochete which infects short-tailed shrews (Blarina brevicauda) an d white-footed mice (Peromyscus leucopus) has been shown previously to be ultrastructurally and serologically distinct from other spirochete s. Two of the original isolates from Connecticut and Minnesota and 16 new isolates obtained from shrews captured in Minnesota were character ized phenotypically and genetically in this study, A comparative analy sis of the 16S rRNA sequences of two shrew isolates and one mouse isol ate and the 16S rRNA sequences of 16 other spirochetes and Escherichia coli revealed that these organisms exhibited low levels of similarity (range of similarity values, 73.9 to 77.8%; average level of similari ty, 74.7%). The shrew and mouse isolates which we examined formed a de eply branching subgroup that was clearly distinct from the other gener a of spirochetes examined, These and other results indicated that the new spirochetes represent a unique taxon in the order Spirochaetales. Accordingly, we propose that they should be classified as members of a new genus, Brevinema, The three strains of Brevinema which we examine d had 16S rRNA sequences that were nearly identical, We also compared these isolates by using sodium dodecyl sulfate-polyacrylamide gel elec trophoresis, fatty acid and enzyme analyses, restriction endonuclease analysis, and Southern hybridization and found that the levels of gene tic and phenotypic homogeneity among the strains were very high, We co ncluded that the isolates which we examined were members of a single s pecies, for which we propose the name Brevinema andersonii, The type s train of Brevinema andersonii is CT11616 (= ATCC 43811). The guanine-p lus-cytosine content of the DNA of this species was determined to be 3 4 to 36 mol% by the thermal denaturation method.