Leptospira borgpetersenii

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A Microbial Biorealm page on the genus Leptospira borgpetersenii

Classification

Higher order taxa

Bacteria; Spirochaetes; Spirochaetes (class); Spirochaetales; Leptospiraceae; Leptospira

Strains: Leptospira borgpetersenii serovar Hardjo-bovis L550. Leptospira borgpetersenii serovar Hardjo-bovis JB197.

Species

Leptospira borgpetersenii

Description and significance

Leptospira borgpetersenii are Gram-negative bacteria with a spiral shape. It contains no endospores but is motile. They are aerobic spirochetes. Leptospira borgpetersenii is a bacterial pathogen of cattle and it also causes zoonotic infections in humans. It is important because it poses a significant public health problem because leptospirosis causes organ failure in the liver, lungs, kidney, and brain (Naiman, Brian M. et. al.). It was first identified in 2003 on Yoroshomi Island of the Amami Islands in Japan. It was identified by means of flaB sequencing, 16S rDNA sequencing and gyrB sequencing (Hiroki Kawabata et. al.).

Genome structure

There are two different strains of this organism which have some similarities and some differences. Both strains consist of two circular chromosomes. Leptospira borgpetersenii serovar Hardjo-bovis JB197 has one chromosome of 3,576,473 nucleotides and a second of 299,762 nucleotides. Leptospira borgpetersenii serovar Hardjo-bovis L550 has one chromosome that consists of 3,614,446 nucleotides and a second of 317,336 nucleotides. Both also have a GC content of 40% (Monash University).

Due to the genomic reduction Leptospira borgpetersenii has undergone through its evolutionary history, it has become completely host dependent for nutrients, a feature that is unique to this species of Leptospira. The genes that were lost include those that control important metabolite control and function(Bulach DM et al.).

Cell structure and metabolism

Lipopolyssacharide (LPS) is found on the surface of Leptospira borgpetersenii and constitutes the majority of the structure. Slight variations in the LPS result in the wide array of serovars that exist. Although the LPS is extremely important, little is known about its genetics and chemistry. The repeating sugar portion of the LPS, the O-antigen, defines each of the different strains and has been successfully identified for Leptospira borgpetersenii.

Leptospira borgpetersenii is a chemoorganotroph and it uses oxygen as its electron receptor. These organisms are unable to use sugar as a source for carbon even though they can synthesize a multitude of carbohydrates. The main energy source is long chain fatty acids which are obtained through β-oxidation (Monash University).

Ecology

Because this organism is a pathogen, its habitat is host-associated. It requires an aerobic and non-halophilic environment. Leptospira borgpetersenii is also a mesophilic organism, growing optimally at 28-32 °C. Before infection occurs, the bacteria live in stagnant water reservoirs, such as lakes and ponds. (More about the environment is described in the “Pathology” section).

Pathology

Leptospirosis is the most common bacterial zoonotic disease in domestic or wild animals and is caused by infection from the spirochaetes. The disease is a direct result of infection by this pathogen and is responsible for high mortality rates in the dairy industry due to agalactia, abortion, stillbirth, birth of weak calves, and reduced fertility. This organism colonizes in the kidney and reproductive tracts of infected animals and can cause zoonotic infections in humans. The majority of cases arise in people working in the farming industry.

Leptospirosis is transferred to humans when fresh water that has been contaminated by infected animal urine comes in contact with open wounds, the eyes, or the mucous membranes. The disease is extremely contagious and occurs more readily during rainfall.

In humans, typical symptoms include fever, chills, headaches, muscle soreness, vomiting, red eyes, jaundice, abdominal pain, diarrhea, and/or rashes. If untreated, leptospriosis can lead to kidney damage, meningitis, liver failure, and respiratory problems. These symptoms usually arise after 4 to 14 days in humans. In animals, the organism travels through the bloodstream and settles in the kidneys where it reproduces. The typical symptoms in animals include fever, loss of appetite, joint pain, nausea, excessive drinking, and jaundice. The symptoms in animals usually arise after 2 to 20 days.

Vaccinations to Leptospira borgpetersenii have recently been developed. Although vaccinations already existed for other species of Leptospira that caused leptospirosis, these anti-leptospiral lipopolysaccharide antibodies do not protect against Leptospira borgpetersenii. Rather, renal colonization and urinary shedding are used to induce a cell-mediated respone. Nearly fifty-eight percent of all leptospirosis cases are caused by infection due to Leptospira borgpetersenii, not from the other species of Leptospira (Naiman, Brian M. et. al.).

Application to Biotechnology

Leptospira borgpetersenii is a bacterial pathogen that is not used for biotechnology.

Current Research

September 2006: Recent research has been conducted that concludes that Leptospira borgpetersenii requires strict host-to-host transmission. Evidence has been collected that shows how Leptospira borgpetersenii has undergone genomic reduction and therefore is no longer able to survive nutrient deprivation. Gene loss, however, does not affect the organism’s virulent abilities. Instead, it simply increases the organism’s dependence on the host cell for its nutrients. The genomic portions that are lost have tremendous metabolic implications. This is consistent with the evidence that Leptospira borgpetersenii is transmitted only by direct contact with the disease unlike an extremely similar species Leptospira interrogans, which does not contain this genomic reduction. (Bulach DM et. al.)

July 1998: In an experiment, bovine embryos were produced by in vitro fertilization and exposed to Leptospira borgpetersenii, to mimic conditions in the reproductive tracts of naturally infected animals. These embryos had their zona pellucida intact. They were exposed for 24 hours and washed accordingly. Once they were observed under scanning electron microscopy and transmission electron microscopy, it became evident that the spirochaetes were entering the pores of the embryos via the pores of the zona pellucida. Although the concentration of Leptospira borgpetersenii was placed intentionally high, it is evident that it is possible for the disease to enter an embryo in vitro, as opposed to previously thought. Through these means, it becomes apparent that the disease can easily be transferred from generation to generation via the reproductive tract (Bielanski).

July 1999: Research has been conducted on 17 Leptospira strains isolated from beef cattle in Zimbabwe. Their DNA relatedness was determined using the hydroxyapatite method. All of the strains from Zimbabwe belong to either Leptospira borgpetersenii or Leptospira kirschneri. All 17 of the serogroups that were studied were 86% or more related with 2% or less divergence within each respective species. This research shows the phylogenetic relationships of the different species of Leptospira. On the continent of Africa, species diversity has been limited as only slight variations of two species exist, challenging the origins of the bacteria (Feresu).

References

Feresu, SB et. al. “DNA relatedness of Leptospira strains isolated from beef cattle in Zimbabwe.” 1999. PubMed Central. http://ijs.sgmjournals.org/cgi/reprint/49/3/1111

Bulach DM et. al. “Genome reduction in Leptospira borgpetersenii reflects limited transmission potential.” 2006 Sep 26. Proc Natl Acad Sci U S A. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1599999

Bielanski AB et. al. “Leptospira borgpetersenii serovar hardjo type hardjobovis in bovine embryos fertilized in vitro.” 1998. PubMed Central. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=9684055

Hiroki Kawabata et. al. “First record of Leptospira borgpetersenii isolation in the Amami Islands, Japan.” 2006. Microbiol Immunol. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16785714&query_hl=1&itool=pubmed_docsum

Monash University. 22 October 2006. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=genomeprj&cmd=Retrieve&dopt=Overview&list_uids=16148

Naiman, Brian M. et. al. “Evaluation of Type 1 Immune Response in Naïve and Vaccinated Animals following Challenge with Leptospira borgpetersenii Serovar Hardjo: Involvement of WC1+ γδ and CD4 T Cells.” 2002. American Society for Microbiology. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=12379692

Bulach DM et al. “Lipopolysaccharide biosynthesis in Leptospira.” 2000. Pubmed. http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=11075908&ordinalpos=33&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum


Edited by student of Rachel Larsen and Kit Pogliano

KMG