@article {783,
	title = {Antigen polymorphism in Borrelia hermsii, a clonal pathogenic bacterium.},
	journal = {Proc Natl Acad Sci U S A},
	volume = {98},
	year = {2001},
	month = {2001 Dec 18},
	pages = {15038-43},
	abstract = {The relapsing fever spirochete, Borrelia hermsii, escapes immune selection by alternating expression of surface lipoprotein alleles. The switch results from a duplicative transposition of one of several surface lipoprotein-encoding nucleotide sequences into the singular expression site. These nucleotide sequences constitute a large gene family whose diversity originated, in some cases, before the major divergences of Borrelia species. We have examined the B. hermsii vsp subfamily of alleles, which are carried on linear plasmids within each cell and maintained in several diverse copies as an antigenic archive. Each encodes a distinct serotype-specific protein. We sequenced more than 90\% of the alleles within a single strain-B. hermsii strain HS1. A preponderance of allelic mosaicism suggests that intragenic recombination, coupled with selection imposed by host immune response, has driven diversification of the archived ensemble of vsp alleles. The recombinational diversification of vsp alleles generates change in the associated serotypes of the magnitude (30-40\% amino acid differentiation) necessary for overcoming cross-reactivity of neutralizing antibodies. We conclude that evolution of vsp has occurred by punctuated occurrence of allelic differentiation, rather than by gradual selection of incremental point mutations that do not meet the threshold for antigenic diversity.},
	keywords = {Antigens, Bacterial, Base Sequence, Borrelia, DNA, Bacterial, Polymorphism, Genetic, Repetitive Sequences, Nucleic Acid},
	issn = {0027-8424},
	doi = {10.1073/pnas.071042098},
	author = {Rich, S M and Sawyer, S A and Barbour, A G}
}
@article {785,
	title = {Lone star tick-infecting borreliae are most closely related to the agent of bovine borreliosis.},
	journal = {J Clin Microbiol},
	volume = {39},
	year = {2001},
	month = {2001 Feb},
	pages = {494-7},
	abstract = {Although Borrelia theileri, the agent of bovine borreliosis, was described at the turn of the century (in 1903), its relationship with borreliae causing Lyme disease or relapsing fever remains undescribed. We tested the previously published hypothesis that spirochetes infecting Lone Star ticks (Amblyomma americanum) may comprise B. theileri by analyzing the 16S ribosomal DNAs (rDNAs) and flagellin genes of these spirochetes. B. theileri, the Amblyomma agent, and B. miyamotoi formed a natural group or clade distinct from but most closely related to that of the relapsing fever spirochetes. B. theileri and the Amblyomma agent were 97 and 98\% similar at the nucleotide level within the analyzed portions of the 16S rDNA and the flagellin gene respectively, suggesting a recent divergence. The agent of bovine borreliosis might be explored as a surrogate antigen for the as-yet-uncultivatable Amblyomma agent in studies designed to explore the etiology of a Lyme disease-like infection associated with Lone Star ticks.},
	keywords = {Animals, Borrelia, Borrelia Infections, Cattle, Cattle Diseases, Flagellin, Humans, Lyme Disease, Phylogeny, Relapsing Fever, RNA, Bacterial, RNA, Ribosomal, 16S, Species Specificity, Tick-Borne Diseases, Ticks},
	issn = {0095-1137},
	doi = {10.1128/JCM.39.2.494-497.2001},
	author = {Rich, S M and Armstrong, P M and Smith, R D and Telford, S R}
}
@article {797,
	title = {A new Borrelia infecting Lone Star ticks.},
	journal = {Lancet},
	volume = {347},
	year = {1996},
	month = {1996 Jan 6},
	pages = {67-8},
	keywords = {Animals, Base Sequence, Borrelia, Borrelia Infections, Deer, Disease Vectors, DNA Primers, Maryland, Molecular Sequence Data, Ticks},
	issn = {0140-6736},
	author = {Armstrong, P M and Rich, S M and Smith, R D and Hartl, D L and Spielman, A and Telford, S R}
}
