Transgenic functional complementation with a transmission -associated protein restores spirochete infectivity by tick bite

Publication date: Available online 20 January 2020Source: Ticks and Tick-borne DiseasesAuthor(s): Tom G. Schwan, Sandra J. Raffel, James M. BattistiAbstractThe relapsing fever spirochete Borrelia hermsii and the Lyme disease spirochete Borrelia burgdorferi sensu stricto each produces an abundant, orthologous, outer membrane protein, Vtp and OspC, respectively, when transmitted by tick bite. Gene inactivation studies have shown that both proteins are essential for spirochete infectivity when transmitted by their respective tick vectors. Therefore, we transformed a vtp-minus mutant of B. hermsii with ospC from B. burgdorferi and examined the behavior of this transgenic spirochete in its soft tick vector Ornithodoros hermsi. IFA staining indicated up to 97.8% of the transgenic B. hermsii upregulated OspC in the ticks’ salivary glands compared to no more than 12.8% in the midgut, similar to our previous findings with wild-type B. hermsii producing Vtp. Transformation with ospC also restored B. hermsii infectivity to mice when fed upon by infected ticks. Previous sequence analysis of Vtp for 79 isolates and DNA samples of B. hermsii in our laboratory showed this protein is highly polymorphic with 9 divergent amino acid types, yet strikingly the signal peptide is identical among all samples and the same for all OspC signal peptides for B. burgdorferi and related species examined to date. Searches in multiple genome sequences for other species of relapsing fever spirochetes failed...
Source: Ticks and Tick borne Diseases - Category: Zoology Source Type: research