Deoxyribonucleic Acid Hybridization Among Selected Leptospiral Serotypes

Abstract

The deoxyribonucleic acids (DNA) from phenotypically unusual Leptospira strains were compared to each other and to reference strains of existing genetic groups. In the "pathogenic" genetic complex, three groups emerged as genetically distinct. Representative examples of these groups were bataviae strain Van Tienen, javanica strain Veldrat Bataviae, and ranarum strain Iowa City Frog. The serologically different muenchen strain Muenchen 90C, icterohaemorrhagiae strain RGA, and kabura strain Kabura were found to be closely related to bataviae strain Van Tienen. The "saprophytic"genetic complex also contained three inter-related groups. The representative examples were patoc strain Patoc I, codice strain CDC, and Turtle strain A-183. Strain 3055 of serotype illini appeared t o have unique nucleotide sequences and was placed in a third genetic complex of its own. Partial relatedness between DNA could be emphasized by increasing the salt concentrations in the incubation media. This could not be attributed t o the methods of annealing but appeared to be dependent upon the genetic relatedness between the heterologous DNA.The genus Leptospira can be separated into two major divisions, the pathogenic and the so-called "sap rop hy t icy' or "bifle xa " lep t 0-spiras. The latter are usually found in fresh surface waters and are rarely found in animals. In addition to infectivity, various phenotypic properties serve to separate members of the two divisions (1 8). Using deoxyribonucleic acid (DNA) base composition determinations and specific DNA-DNA annealing tests in agar matrices, Haapala et al. (7) demonstrated genetic differences between, as well as within, serotypes in the two divisions. Two distinct genetic groups were demonstrated among selected strains within each of the pathogenic and biflexa serotypes. The serological relationships among lep tospiras did not necessarily denote genetic relatedness; however, strains of the same or very similar serotypes appeared to be in the same genetic group. The two genetic groups of pathogenic lep tospiras could be differentiated from each other and from the two biflexa groups by a number of phenotypic characteristics which also served as a basis for the leptospiral groups described by Johnson and Harris (9). The principal differentiating attributes were lipase production and relative resistance to the bacteriostatic action of 8-azaguanine (AZA) and 2,6-diaminopurine (DAP).The genetic groups of pathogenic strains represented by strains of serotypes bataviae and javanica corresponded to the Johnson and Harris biological groups 1 and 2, respectively. Group 1 strains were sensitive to AZA and DAP and had lipase activity, whereas group 2 strains were sensitive to AZA, resistant t o DAP, and lacked lipase activity. The two genetic groups of biflexa strains were phenotypically indistinguishable and fit into the Johnson and Harris biological group 3 , which was characterized by resistance to both purine analogues and by positive lipase activity.

Movement of antibody-coated latex beads attached to the spirochete Leptospira interrogans.

“…DISCUSSION The present communication reports that Ab-beads attached to two serovars of L. interrogans are displaced backwards along the lengths of swimming cells. Because these serovars belong to markedly different DNA hybridization groups (15), the results obtained are likely to be relevant to other serovars of the genus. Jarosch observed a similar phenomenon of India ink particles being displaced along the length ofL.…”

Phylogenetic analysis of the spirochetes

“…The first subgroup contains the saprophytic leptospires (L. biflexa serovar patoc and turtle strain A-183 [which had identical sequences]) and the parasitic leptospires (L. interrogans serovar canicola [17] and serovar pomona [which had nearly identical sequences]), with 90.3% similarity. The identical sequences of the patoc serovar and strain A-183 were not surprising inasmuch as the patoc strain had approximately 50% DNA relatedness with strain A-183 (6). The other subgroup consists of the single species, Leptonema illini, with an average level of 83.2% sequence similarity with members of the first subgroup.…”

Cloning and analysis of the leuB gene of Leptospira interrogans serovar pomona

“…A clone (pWVL1) was isolated from this genomic library which complemented three independent leuB mutations in E. coli. (Brendle et al, 1974;Yasuda et al, 1987). Tn5 insertions flanking the leuB gene did not inactivate gene expression, suggesting that expression of the gene depends on its own promoter rather than on a pUC13 promoter.…”