Infection of Ixodes scapularis ticks with Rickettsia monacensis expressing green fluorescent protein

A model system

Gerald D Baldridge, Timothy J Kurtti, Nicole Burkhardt, Abigail S. Baldridge, Curtis M. Nelson, Adela S. Oliva, Ulrike G Munderloh

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Ticks (Acari: Ixodidae) are ubiquitous hosts of rickettsiae (Rickettsiaceae: Rickettsia), obligate intracellular bacteria that occur as a continuum from nonpathogenic arthropod endosymbionts to virulent pathogens of both arthropod vectors and vertebrates. Visualization of rickettsiae in hosts has traditionally been limited to techniques utilizing fixed tissues. We report epifluorescence microscopy observations of unfixed tick tissues infected with a spotted fever group endosymbiont, Rickettsia monacensis, transformed to express green fluorescent protein (GFP). Fluorescent rickettsiae were readily visualized in tick tissues. In adult female, but not male, Ixodes scapularis infected by capillary feeding, R. monacensis disseminated from the gut and infected the salivary glands that are crucial to the role of ticks as vectors. The rickettsiae infected the respiratory tracheal system, a potential dissemination pathway and possible infection reservoir during tick molting. R. monacensis disseminated from the gut of capillary fed I. scapularis nymphs and was transstadially transmitted to adults. Larvae, infected by immersion, transstadially transmitted the rickettsiae to nymphs. Infected female I. scapularis did not transovarially transmit R. monacensis to progeny and the rickettsiae were not horizontally transmitted to a rabbit or hamsters. Survival of infected nymphal and adult I. scapularis did not differ from that of uninfected control ticks. R. monacensis did not disseminate from the gut of capillary fed adult female Amblyomma americanum (L.), or adult Dermacentor variabilis (Say) ticks of either sex. Infection of I. scapularis with R. monacensis expressing GFP provides a model system allowing visualization and study of live rickettsiae in unfixed tissues of an arthropod host.

Original languageEnglish (US)
Pages (from-to)163-174
Number of pages12
JournalJournal of Invertebrate Pathology
Volume94
Issue number3
DOIs
StatePublished - Mar 1 2007

Fingerprint

Rickettsia
Ixodes scapularis
tick
green fluorescent protein
ticks
protein
infection
arthropods
arthropod
digestive system
endosymbionts
endosymbiont
nymphs
Rickettsiaceae
visualization
Dermacentor variabilis
Amblyomma americanum
tick control
Ixodidae
salivary glands

Keywords

  • Endosymbiont
  • GFP
  • Ixodidae
  • Live imaging
  • Rickettsia
  • Ticks
  • Tracheal dissemination

Cite this

Infection of Ixodes scapularis ticks with Rickettsia monacensis expressing green fluorescent protein : A model system. / Baldridge, Gerald D; Kurtti, Timothy J; Burkhardt, Nicole; Baldridge, Abigail S.; Nelson, Curtis M.; Oliva, Adela S.; Munderloh, Ulrike G.

In: Journal of Invertebrate Pathology, Vol. 94, No. 3, 01.03.2007, p. 163-174.

Research output: Contribution to journalArticle

Baldridge, Gerald D ; Kurtti, Timothy J ; Burkhardt, Nicole ; Baldridge, Abigail S. ; Nelson, Curtis M. ; Oliva, Adela S. ; Munderloh, Ulrike G. / Infection of Ixodes scapularis ticks with Rickettsia monacensis expressing green fluorescent protein : A model system. In: Journal of Invertebrate Pathology. 2007 ; Vol. 94, No. 3. pp. 163-174.
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