Outer Membrane Protein A Conservation among Orientia tsutsugamushi Isolates Suggests Its Potential as a Protective Antigen and Diagnostic Target

Research output: Contribution to journalArticle

Authors

External Institution(s)

  • Virginia Commonwealth University
  • Infectious Diseases Laboratory
  • Naval Medical Research Center
  • Shippensburg University
  • Swiss Tropical and Public Health Institute
  • Uniformed Services University of the Health Sciences

Details

Original languageEnglish (US)
Article number63
JournalTropical Medicine and Infectious Disease
Volume3
Issue number2
StatusPublished - Jun 11 2018
Peer-reviewedYes

Abstract

Scrub typhus threatens one billion people in the Asia-Pacific area and cases have emerged outside this region. It is caused by infection with any of the multitude of strains of the bacterium Orientia tsutsugamushi. A vaccine that affords heterologous protection and a commercially-available molecular diagnostic assay are lacking. Herein, we determined that the nucleotide and translated amino acid sequences of outer membrane protein A (OmpA) are highly conserved among 51 O. tsutsugamushi isolates. Molecular modeling revealed the predicted tertiary structure of O. tsutsugamushi OmpA to be very similar to that of the phylogenetically-related pathogen, Anaplasma phagocytophilum, including the location of a helix that contains residues functionally essential for A. phagocytophilum infection. PCR primers were developed that amplified ompA DNA from all O. tsutsugamushi strains, but not from negative control bacteria. Using these primers in quantitative PCR enabled sensitive detection and quantitation of O. tsutsugamushi ompA DNA from organs and blood of mice that had been experimentally infected with the Karp or Gilliam strains. The high degree of OmpA conservation among O. tsutsugamushi strains evidences its potential to serve as a molecular diagnostic target and justifies its consideration as a candidate for developing a broadly-protective scrub typhus vaccine.

    Research areas

  • Anaplasma, Orientia tsutsugamushi, Outer membrane protein A, Rickettsia, Rickettsiales, Scrub typhus

Citation formats

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Evans, SM, Adcox, HE, VieBrock, L, Green, RS, Luce-Fedrow, A, Chattopadhyay, S, Jiang, J, Marconi, RT, Paris, D, Richards, AL & Carlyon, JA 2018, 'Outer Membrane Protein A Conservation among Orientia tsutsugamushi Isolates Suggests Its Potential as a Protective Antigen and Diagnostic Target', Tropical Medicine and Infectious Disease, vol. 3, no. 2, 63. https://doi.org/10.3390/tropicalmed3020063