Borrelia miyamotoi
From Wikipedia, the free encyclopedia
| Borrelia miyamotoi | |
|---|---|
Scientific classification  | |
| Domain: | Bacteria |
| Kingdom: | Pseudomonadati |
| Phylum: | Spirochaetota |
| Class: | Spirochaetia |
| Order: | Spirochaetales |
| Family: | Borreliaceae |
| Genus: | Borrelia |
| Species: | B. miyamotoi |
| Binomial name | |
| Borrelia miyamotoi Fukunaga et al. 1995 | |
Borrelia miyamotoi is a bacterium of the spirochete phylum in the genus Borrelia. A zoonotic organism, B. miyamotoi can infect humans through the bite of several species of hard-shell Ixodes ticks, the same kind of ticks that spread B. burgdorferi, the causative bacterium of Lyme disease. Ixodes ticks are also the primary vector in the spread of babesiosis and anaplasmosis.[1]
B. miyamotoi causes Borrelia miyamotoi disease (BMD) in humans. BMD is a relapsing fever illness that has been reported across the world, often in the same geographic areas where Lyme disease is endemic.[1] Treatment currently follows that of Lyme disease.[2]
History and morphology
B. miyamotoi was discovered in 1995 when it was isolated from a population of Ixodes persulcates ticks on the Japanese island of Hokkaido.[1] The organism was named for Kenji Miyamoto, who initially discovered Borrellia spirochetes in Japan.[3] It was first detected in the United States in 2001.[4]
B. miyamotoi is a gram-negative, anaerobic, obligate parasitic bacterium with a spiraling corkscrew shape.[1][5]
Genetics
The bacterial genome is physically made up of one linear chromosome, twelve linear plasmids, and two circular plasmids, which encode a total of 1362 genes. Four distinct genotypes of B. miyamotoi have been demonstrated based on examples isolated from Asia, Europe, and North America.[2][5]
Borrelia species that cause human disease are classified into two genetic clades, the Lyme borreliosis (LB) clade, and the relapsing fever (RF) clade. B. miyamotoi is a member of the relapsing fever (RF) clade.[5] The glpQ gene and its resulting GlpQ protein are conserved in the RF clade of Borrelia, which makes it possible to distinguish them from LB group Borrellia in testing.[5]
Transmission
Unlike B. burgdoferi, B. miyamotoi exhibits transovarial transmission, whereby the bacterium is passed from an adult tick directly into the eggs of new larvae within the ovaries. This mode of transmission has implications for diagnosis of disease because a very small larva can attach to a human host and go undetected.[1]
Virulence factors
B. miyamotoi employs antigenic variation and variable membrane proteins (VMPs) that help it to evade the human immune system.[6] It is also known to evade components of the complement cascade, part of innate immune system, which mounts the initial response to an infection.[2][7]