Limits...
Transmission dynamics of Borrelia turicatae from the arthropod vector.

Boyle WK, Wilder HK, Lawrence AM, Lopez JE - PLoS Negl Trop Dis (2014)

Bottom Line: Spirochetes were also detected in acini lumen of salivary glands by SEM.Upon host entry, B. turicatae did not require colonization of the bite site to establish murine infection.These results suggest that once B. turicatae colonizes the salivary glands the spirochetes are preadapted for rapid entry into the mammal.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Mississippi State University, Starkville, Mississippi, United States of America.

ABSTRACT

Background: With the global distribution, morbidity, and mortality associated with tick and louse-borne relapsing fever spirochetes, it is important to understand the dynamics of vector colonization by the bacteria and transmission to the host. Tick-borne relapsing fever spirochetes are blood-borne pathogens transmitted through the saliva of soft ticks, yet little is known about the transmission capability of these pathogens during the relatively short bloodmeal. This study was therefore initiated to understand the transmission dynamics of the relapsing fever spirochete Borrelia turicatae from the vector Ornithodoros turicata, and the subsequent dissemination of the bacteria upon entry into murine blood.

Methodology/principal findings: To determine the minimum number of ticks required to transmit spirochetes, one to three infected O. turicata were allowed to feed to repletion on individual mice. Murine infection and dissemination of the spirochetes was evaluated by dark field microscopy of blood, quantitative PCR, and immunoblotting against B. turicatae protein lysates and a recombinant antigen, the Borrelia immunogenic protein A. Transmission frequencies were also determined by interrupting the bloodmeal 15 seconds after tick attachment. Scanning electron microscopy (SEM) was performed on infected salivary glands to detect spirochetes within acini lumen and excretory ducts. Furthermore, spirochete colonization and dissemination from the bite site was investigated by feeding infected O. turicata on the ears of mice, removing the attachment site after engorment, and evaluating murine infection.

Conclusion/significance: Our findings demonstrated that three ticks provided a sufficient infectious dose to infect nearly all animals, and B. turicatae was transmitted within seconds of tick attachment. Spirochetes were also detected in acini lumen of salivary glands by SEM. Upon host entry, B. turicatae did not require colonization of the bite site to establish murine infection. These results suggest that once B. turicatae colonizes the salivary glands the spirochetes are preadapted for rapid entry into the mammal.

Show MeSH

Related in: MedlinePlus

Immunoblots from four mice demonstrating seroconversion in animals when spirochetes were detected by microscopy or qPCR after ticks fed to repletion (A), or were interrupted after attaching for 15 seconds (B).Animals that were fed on by infected ticks yet spirochetes were undetectable in murine blood (C and D). B. turicatae protein lysates and rBipA were electrophoresed in lane 1 and 2, respectively. Serum samples were collected from animals four weeks after tick feeding. Molecular masses (kilodaltons) are indicated to the left of each immunoblot.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3974661&req=5

pntd-0002767-g001: Immunoblots from four mice demonstrating seroconversion in animals when spirochetes were detected by microscopy or qPCR after ticks fed to repletion (A), or were interrupted after attaching for 15 seconds (B).Animals that were fed on by infected ticks yet spirochetes were undetectable in murine blood (C and D). B. turicatae protein lysates and rBipA were electrophoresed in lane 1 and 2, respectively. Serum samples were collected from animals four weeks after tick feeding. Molecular masses (kilodaltons) are indicated to the left of each immunoblot.

Mentions: The lack of available information regarding transmission efficiencies by O. turicata initiated a comparative study feeding one to three third stage nymphal ticks on a given mouse. All ticks engorged within 10–30 minutes. Comparing microscopy, qPCR, and serological responses indicated that immunoblotting and qPCR results were similar and more consistent in assessing murine infection than dark-field microscopy (Table 1). For example, when spirochetes were detected in the blood by microscopy or qPCR, mice seroconverted to B. turicatae protein lysates and rBipA (Figure 1 A and B), an antigen for relapsing fever spirochetes [18], [19]. Animals in which spirochetes were not detected in the blood by qPCR failed to seroconvert (Figure 1 C and D). Serological responses from the four mice (Figure 1 A–D) were representative of remaining animals that were fed upon by infected ticks. Murine infection rates after one to three O. turicata fed indicated that three ticks provided an infectious dose to a minimum of 80% of mice (Table 1). Also, IFA enabled B. turicatae visualization in the salivary glands from 9 of 10 ticks that were individually fed on mice (Figure 2 A–C), suggesting that while most ticks were colonized with spirochetes, they failed to deliver a sufficient infectious dose.


Transmission dynamics of Borrelia turicatae from the arthropod vector.

Boyle WK, Wilder HK, Lawrence AM, Lopez JE - PLoS Negl Trop Dis (2014)

Immunoblots from four mice demonstrating seroconversion in animals when spirochetes were detected by microscopy or qPCR after ticks fed to repletion (A), or were interrupted after attaching for 15 seconds (B).Animals that were fed on by infected ticks yet spirochetes were undetectable in murine blood (C and D). B. turicatae protein lysates and rBipA were electrophoresed in lane 1 and 2, respectively. Serum samples were collected from animals four weeks after tick feeding. Molecular masses (kilodaltons) are indicated to the left of each immunoblot.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3974661&req=5

pntd-0002767-g001: Immunoblots from four mice demonstrating seroconversion in animals when spirochetes were detected by microscopy or qPCR after ticks fed to repletion (A), or were interrupted after attaching for 15 seconds (B).Animals that were fed on by infected ticks yet spirochetes were undetectable in murine blood (C and D). B. turicatae protein lysates and rBipA were electrophoresed in lane 1 and 2, respectively. Serum samples were collected from animals four weeks after tick feeding. Molecular masses (kilodaltons) are indicated to the left of each immunoblot.
Mentions: The lack of available information regarding transmission efficiencies by O. turicata initiated a comparative study feeding one to three third stage nymphal ticks on a given mouse. All ticks engorged within 10–30 minutes. Comparing microscopy, qPCR, and serological responses indicated that immunoblotting and qPCR results were similar and more consistent in assessing murine infection than dark-field microscopy (Table 1). For example, when spirochetes were detected in the blood by microscopy or qPCR, mice seroconverted to B. turicatae protein lysates and rBipA (Figure 1 A and B), an antigen for relapsing fever spirochetes [18], [19]. Animals in which spirochetes were not detected in the blood by qPCR failed to seroconvert (Figure 1 C and D). Serological responses from the four mice (Figure 1 A–D) were representative of remaining animals that were fed upon by infected ticks. Murine infection rates after one to three O. turicata fed indicated that three ticks provided an infectious dose to a minimum of 80% of mice (Table 1). Also, IFA enabled B. turicatae visualization in the salivary glands from 9 of 10 ticks that were individually fed on mice (Figure 2 A–C), suggesting that while most ticks were colonized with spirochetes, they failed to deliver a sufficient infectious dose.

Bottom Line: Spirochetes were also detected in acini lumen of salivary glands by SEM.Upon host entry, B. turicatae did not require colonization of the bite site to establish murine infection.These results suggest that once B. turicatae colonizes the salivary glands the spirochetes are preadapted for rapid entry into the mammal.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Mississippi State University, Starkville, Mississippi, United States of America.

ABSTRACT

Background: With the global distribution, morbidity, and mortality associated with tick and louse-borne relapsing fever spirochetes, it is important to understand the dynamics of vector colonization by the bacteria and transmission to the host. Tick-borne relapsing fever spirochetes are blood-borne pathogens transmitted through the saliva of soft ticks, yet little is known about the transmission capability of these pathogens during the relatively short bloodmeal. This study was therefore initiated to understand the transmission dynamics of the relapsing fever spirochete Borrelia turicatae from the vector Ornithodoros turicata, and the subsequent dissemination of the bacteria upon entry into murine blood.

Methodology/principal findings: To determine the minimum number of ticks required to transmit spirochetes, one to three infected O. turicata were allowed to feed to repletion on individual mice. Murine infection and dissemination of the spirochetes was evaluated by dark field microscopy of blood, quantitative PCR, and immunoblotting against B. turicatae protein lysates and a recombinant antigen, the Borrelia immunogenic protein A. Transmission frequencies were also determined by interrupting the bloodmeal 15 seconds after tick attachment. Scanning electron microscopy (SEM) was performed on infected salivary glands to detect spirochetes within acini lumen and excretory ducts. Furthermore, spirochete colonization and dissemination from the bite site was investigated by feeding infected O. turicata on the ears of mice, removing the attachment site after engorment, and evaluating murine infection.

Conclusion/significance: Our findings demonstrated that three ticks provided a sufficient infectious dose to infect nearly all animals, and B. turicatae was transmitted within seconds of tick attachment. Spirochetes were also detected in acini lumen of salivary glands by SEM. Upon host entry, B. turicatae did not require colonization of the bite site to establish murine infection. These results suggest that once B. turicatae colonizes the salivary glands the spirochetes are preadapted for rapid entry into the mammal.

Show MeSH
Related in: MedlinePlus