Implications of back-and-forth motion and powerful propulsion for spirochetal invasion

The spirochete Leptospira spp. can move in liquid and on a solid surface using two periplasmic flagella (PFs), and its motility is an essential virulence factor for the pathogenic species. Mammals are infected with the spirochete through the wounded dermis, which implies the importance of behaviors on the boundary with such viscoelastic milieu; however, the leptospiral pathogenicity involving motility remains unclear. We used a glass chamber containing a gel area adjoining the leptospiral suspension to resemble host dermis exposed to contaminated water and analyzed the motility of individual cells at the liquid-gel border. Insertion of one end of the cell body to the gel increased switching of the swimming direction. Moreover, the swimming force of Leptospira was also measured by trapping single cells using an optical tweezer. It was found that they can generate [Formula: see text] 17 pN of force, which is [Formula: see text] 30 times of the swimming force of Escherichia coli. The force-speed relationship suggested the load-dependent force enhancement and showed that the power (the work per unit time) for the propulsion is [Formula: see text] 3.1 × 10-16 W, which is two-order of magnitudes larger than the propulsive power of E. coli. The powerful and efficient propulsion of Leptospira using back-and-forth movements could facilitate their invasion.

A Spirochaete is suggested as the causative agent of Akoya oyster disease by metagenomic analysis

Mass mortality that is acompanied by reddish browning of the soft tissues has been occurring in cultured pearl oyster, Pinctada fucata martensii. The disease is called Akoya oyster disease (AOD). Although spreading pattern of the disease and transmission experiments suggest that the disease is infectious, the causative agent has not yet been identified. We used shotgun and 16S rRNA-based metagenomic analysis to identify genes that are present specifically in affected oysters. The genes found only in diseased oysters were mostly bacterial origin, suggesting that the causative agent was a bacterial pathogen. This hypothesis was supported by the inhibition of AOD development in naïve oysters injected with the hemolymph of diseased animals followed immediately with penicillin bath-administration. Further analyses of the hemolymph and mantle specifically and universally detected genes of bacteria that belong to phylum Spirochaetes in diseased pearl oysters but not in healthy oysters. By in situ hybridization or immunostaining, a Brachyspira-like bacterium was observed in the smears of hemolymph from affected oysters, but not from healthy oysters. Phylogenetic analysis using 16S rRNA sequences showed that the presumptive causative bacterium was outside of but most closely related to family Brachyspiraceae. We propose ‘Candidatus Maribrachyspira akoyae’ gen. nov, sp nov., for this bacterium.

Analysis of the ability of spirochete species associated with relapsing fever, avian borreliosis, and epizootic bovine abortion to bind factor H and cleave c3b

Some Borrelia species associated with Lyme disease bind the complement-regulatory protein factor H (fH), a process that may aid in immune evasion. In this report we demonstrate that some Borrelia species associated with relapsing fever bind fH, but not those associated with avian borreliosis and epizootic bovine abortion. Cell-bound fH was also found to mediate cleavage of exogenously supplied human C3b, demonstrating the biological relevance of fH binding and its possible importance in the pathogenesis of the relapsing-fever spirochetes.

Identification of a new intestinal spirochete with pathogenicity for chickens

Two intestinal spirochete isolates obtained from chickens with diarrhea were examined by electron microscopy, biochemical tests, rRNA gene restriction pattern analysis, and multilocus enzyme electrophoresis. One isolate (strain 91-1207/C1) was pathogenicity tested in vivo in chickens. The chicken spirochetes were morphologically indistinguishable from Serpulina innocens and Serpulina hyodysenteriae and phenotypically similar to S. innocens. However, the chicken spirochetes could be distinguished from S. innocens, S. hyodysenteriae, and other swine intestinal spirochetes by rRNA gene restriction pattern analysis and multilocus enzyme electrophoresis. In pathogenicity tests in 1-day-old chicks and 14-month-old hens, chicken spirochete 91-1207/C1 produced pale-yellow, watery cecal contents and mild lymphocytic typhlitis. These findings support the conclusion that avian intestinal spirochetes can be pathogenic to commercial poultry and that the microorganisms are different from intestinal spirochetes that infect pigs.

[Experimental induction of foot rot in sheep]

By means of local strains Bacteroides nodusus was reproduced experimentally a case of foot-rot with sheep. For the appearance and the development of the disease it was necessary, before the infection, to keep the sheep in damp and uncleaned from fecal impurities room. Besides that, of decisive importance was the scarification of the skin-horny junction in the interungular slit. The combination of Bacteroides nodusus with Spirohaeta penorta and Corynebacterium piogenes resulted in more serious changes in the infected hooves.

Intestinal spirochaetosis

An abnormal condition of the large intestine is described in which the surface epithelium is infested by short spirochaetes. Diagnosis can be made by light microscopy. A review of 14 cases diagnosed by rectal biopsy and 62 cases involving the appendix shows no consistent symptom complex. The possible significance is discussed.

Spirochete from the rabbit tick, Haemaphysalis leporispalustris (Packard). I. Isolation and preliminary characterization

An unidentified spirochete, referred to as the 277F agent, was isolated from Haemaphysalis leporispalustris ticks from two cottontail rabbits by inoculation of the tick suspension into embryonated chicken eggs. Because of its minute width (0.1 mu), the organism was difficult to see when stained by the Giemsa method, but was readily demonstrated by silver impregnation or fluorescent-antibody procedures. In dark-field microscopy, the spirochetes appeared uniformly and rather tightly coiled, and exhibited typical corkscrewlike motility. After yolk-sac inoculation, the agent was highly lethal for chick embryos and was recovered in large quantity from several embryonic tissues and fluids. It could also be maintained in nonfertile eggs and in an enriched liquid medium. This previously undescribed spirochete could pass through Berkefeld N but not Seitz EK filters. It was relatively resistant to heat and to penicillin or sulfadiazine, but was markedly inhibited by streptomycin, broad-spectrum antibiotics, and homologous neutralizing antiserum. Of several species of animals tested for susceptibility to this spirochete, only the snowshoe hare gave evidence of infection.