title: Transovarial Transmission of Co-Existing Orientia tsutsugamushi Genotypes in Laboratory-Reared Leptotrombidium imphalum.
abstract: The co-evolution of Orientia tsutsugamushi and its vector/host Leptotrombidium mites is important for this bacterium to survive and exist in its environment. The data in this study demonstrated that O. tsutsugamushi has adapted to take advantage of the parasitic nature of the host's larval stage and thus increase its chance of transmission to a vertebrate host and potentially to other vector mites by increasing its density at the time of transmission. Our data demonstrated that during the larval stage the density of O. tsutsugamushi was at its highest level compared to other life stages (Kruskal-Wallis, p < 0.0001). We further revealed that the different O. tsutsugamushi 56-kDa type-specific antigen (TSA) genotypes within the mite were maintained and preserved during transovarial transmission from the Leptotrombidium imphalum, lines Li-3 and Li-5. No sequence difference of 56-kDa TSA gene (variable domain I-III, 765 bp) was observed between the UT302-like genotype found in mothers and their offspring (100% identity). However, one or two nonsynonymous mutations in the 56-kDa TSA gene were observed in the Karp-like genotypes found in the F1 offspring with a percent difference ranging from 0.13 to 0.26 for nucleotide sequences and from 0.39 to 0.78 for amino acid sequences. Additionally, the composition of co-existing O. tsutsugamushi genotypes was maintained in L. imphalum lines through transsovarial and transstadial transmission processes; however, the proportion of these genotypes in each stage varied (larva, nymph, adult). These results show some of the key characteristics of O. tsutsugamushi maintenance within and transmission among its vector/host L. imphalum.
authors.affiliation: 1 Department of Entomology, United States Army Medical Component-Armed Forces Research Institute of Medical Sciences , Bangkok, Thailand .
authors.forename: Ratree
authors.initials: R
authors.lastname: Takhampunya
authors.affiliation: 1 Department of Entomology, United States Army Medical Component-Armed Forces Research Institute of Medical Sciences , Bangkok, Thailand .
authors.forename: Bousaraporn
authors.initials: B
authors.lastname: Tippayachai
authors.affiliation: 1 Department of Entomology, United States Army Medical Component-Armed Forces Research Institute of Medical Sciences , Bangkok, Thailand .
authors.forename: Achareeya
authors.initials: A
authors.lastname: Korkusol
authors.affiliation: 1 Department of Entomology, United States Army Medical Component-Armed Forces Research Institute of Medical Sciences , Bangkok, Thailand .
authors.forename: Sommai
authors.initials: S
authors.lastname: Promsathaporn
authors.affiliation: 1 Department of Entomology, United States Army Medical Component-Armed Forces Research Institute of Medical Sciences , Bangkok, Thailand .
authors.forename: Surachai
authors.initials: S
authors.lastname: Leepitakrat
authors.affiliation: 1 Department of Entomology, United States Army Medical Component-Armed Forces Research Institute of Medical Sciences , Bangkok, Thailand .
authors.forename: Warattaya
authors.initials: W
authors.lastname: Sinwat
authors.affiliation: 1 Department of Entomology, United States Army Medical Component-Armed Forces Research Institute of Medical Sciences , Bangkok, Thailand .
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Schuster
authors.affiliation: 2 Viral and Rickettsial Diseases Department, Naval Medical Research Center , Silver Spring, Maryland.
authors.forename: Allen L
authors.initials: AL
authors.lastname: Richards
mesh_terms: D000818:Animals; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D005838:Genotype; D054884:Host-Pathogen Interactions / Q000502:physiology; D007814:Larva / Q000382:microbiology; D009758:Nymph / Q000382:microbiology; D012285:Orientia tsutsugamushi / Q000235:genetics*; D010053:Ovary / Q000382:microbiology*; D014324:Trombiculidae / Q000235:genetics / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial
keywords: Co-existing genotypes; Leptotrombidium imphalum; Orientia tsutsugamushi; Scrub typhus; Transovarial transmission