Development of Genetic System to Inactivate a Borrelia turicatae Surface Protein Selectively Produced within the Salivary Glands of the Arthropod Vector

Background:borrelia turicatae,an agent of tick-borne relapsing fever,is an example of a pathogen that can adapt to disparate conditions found when colonizing the mammalian host and arthropod vector. however,little is known about the genetic factors necessary during the tick-mammalian infectious cycle,therefore we developed a genetic system to transform this species of spirochete. we also identified a plasmid gene that was up-regulated in vitro when b. turicatae was grown in conditions mimicking the tick environment. this 40 kilodalton protein was predicted to be surface localized and designated the borrelia repeat protein a (brpa) due to the redundancy of the amino acid motif gln-gly-asn-val-glu.methodology/principal findings:quantitative reverse-transcriptase polymerase chain reaction using rna from b. turicatae infected ticks and mice indicated differential regulation of brpa during the tick-mammalian infectious cycle. the surface localization was determined,and production of the protein within the salivary glands of the tick was demonstrated. we then applied a novel genetic system for b. turicatae to inactivate brpa and examined the role of the gene product for vector colonization and the ability to establish murine infection.conclusions/significance:these results demonstrate the complexity of protein production in a population of spirochetes within the tick. additionally,the development of a genetic system is important for future studies to evaluate the requirement of specific b. turicatae genes for vector colonization and transmission. © 2013.