ABSTRACT
The virome associated with the corkscrew shaped bacterium Leptospira, responsible for Weil's disease, is scarcely known, and genetic tools available for these bacteria remain limited. To reduce these two issues, potential transposable prophages were searched in Leptospiraceae genomes. The 236 predicted transposable prophages were particularly abundant in the most pathogenic leptospiral clade, being potentially involved in the acquisition of virulent traits. According to genomic similarities and phylogenies, these prophages are distantly related to known transposable phages and are organized into six groups, one of them encompassing prophages with unusual TA-TA ends. Interestingly, structural and transposition proteins reconstruct different relationships between groups, suggesting ancestral recombinations. Based on the baseplate phylogeny, two large clades emerge, with specific gene-contents and high sequence divergence reflecting their ancient origin. Despite their high divergence, the size and overall genomic organization of all prophages are very conserved, a testimony to the highly constrained nature of their genomes. Finally, similarities between these prophages and the three known non-transposable phages infecting L. biflexa, suggest gene transfer between different Caudovirales inside their leptospiral host, and the possibility to use some of the transposable prophages in that model strain.
Subject(s)
Genome, Bacterial , Genome, Viral , Leptospira , Phylogeny , Prophages/genetics , Weil Disease/genetics , Humans , Leptospira/genetics , Leptospira/virology , Sequence Analysis, DNAABSTRACT
The gene polymorphism of the DNAs extracted from reference strains of L. interrogans in China was characterized by LSSP-PCR primered by G1 or G2, which were a pair of specific primers for L. interrogans. The fingerprinting produced by LSSP-PCR showed that serovar lai, serovar canicola, serovar pyrogens, serovar autumnalis, serovar australis, serovar linhai, serovar wolffi and serovar haemolytic have similar patterns, but serovar hebdomadis, serovar javanica, serovar ballum, serovar pomona, serovar spaidjin, serovar tarassov and serovar manahao I have different profiles. This result agreed with the classification of genetic species by Yasuda. The utilization of LSSP-PCR banding patterns in the identification of leptospries in blood samples also gained encouraging results. Compared with the routine methods in genetic species classification, LSSP-PCR has the advantages of rapidity, simplicity and low-cost. It appears to be a promising tool in studying such slowly growing bacteria as leptospires. Further exploration of LSSP-PCR in classification and identification of Leptospires is worthwhile.
Subject(s)
DNA, Bacterial/genetics , Leptospira interrogans/genetics , Gene Amplification , Leptospira interrogans/classification , Polymerase Chain Reaction/methods , Polymorphism, Genetic , Weil Disease/geneticsABSTRACT
Measurements of DNA and study of chromatin status in blood cell nuclei help solve numerous basic problems of biology and medicine. Acid lability of DNA was assessed in 5 patients with grave icterohemorrhagic leptospirosis. The distribution of fluorescence peaks on the curve of neutrophil DNA hydrolysis in patients with grave leptospirosis indicates that functionally low-active acid-resistant DNA fraction predominates in their chromatin. Assessment of acid lability of DNA is proposed to be used for assessing the severity of the pathological process.
Subject(s)
DNA/analysis , Weil Disease/diagnosis , Weil Disease/genetics , Acids , Adult , Aged , Cell Nucleus/ultrastructure , Chromatin/genetics , Female , Fluorescence , Humans , Hydrolysis , Male , Middle Aged , Neutrophils/cytologyABSTRACT
Fifty-five serum samples from patients with leptospirosis treated by the method of high SiO2 concentration salt solution absorption were analysed with the variable sequences of the 16S rRNA genes of Leptospria interrogans as primers. It is shown that the 16S rRNA gene primer is useful for the clinical detection and the epidemic investigation of leptospirosis, and the detecting effect by PCR is superior to that by the blood culture and MAT (P < 0.01).
Subject(s)
Genes, Bacterial , Leptospira interrogans/genetics , Weil Disease/diagnosis , Humans , Polymerase Chain Reaction , RNA, Ribosomal, 16S/genetics , Weil Disease/geneticsABSTRACT
A sensitive assay for Leptospira spp., the causative agent of leptospirosis, was developed on the basis of the polymerase chain reaction (PCR). A 331-bp sequence from the Leptospira interrogans serovar canicola rrs (16S) gene was amplified, and the PCR products were analyzed by DNA-DNA hybridization by using a 289-bp fragment internal to the amplified DNA. Specific PCR products also were obtained with DNA from the closely related nonpathogenic Leptospira biflexa but not with DNA from other spirochetes, such as Borrelia burgdorferi, Borrelia hermsii, Treponema denticola, Treponema pallidum, Spirochaeta aurantia, or more distant organisms such as Escherichia coli, Staphylococcus aureus, Mycobacterium tuberculosis, and Proteus mirabilis. The assay was able to detect as few as 10 bacteria. Leptospira DNA was detected in urine from experimentally infected mice. In addition, the test was found to be suitable for diagnosing leptospirosis in humans. Cerebrospinal fluid and urine from patients with leptospirosis were positive, whereas samples from control uninfected patients were negative.
