A kunitz protease inhibitor from dermacentor variabilis, a vector for spotted fever group rickettsiae, limits rickettsia montanensis invasion

Shane M. Ceraul, Ashley Chung, Khandra T. Sears, Vsevolod L. Popov, Magda Beier-Sexton, M. Sayeedur Rahman, Abdu F. Azad

Research output: Contribution to journalArticle

29 Scopus citations


A defining facet of tick-Rickettsia symbioses is the molecular strategy employed by each partner to ensure its own survival. Ticks must control rickettsial colonization to avoid immediate death. In the current study, we show that rickettsial abundance in the tick midgut increases once the expression of a Kunitz-type serine protease inhibitor from the American dog tick (Dermacentor variabilis) (DvKPI) is suppressed by small interfering RNA (siRNA). A series of in vitro invasion assays suggested that DvKPI limits rickettsial colonization during host cell entry. Interestingly, we observed that DvKPI associates with rickettsiae in vitro as well as in the tick midgut. Collectively, our data demonstrate that DvKPI limits host cell invasion by Rickettsia montanensis, possibly through an association with the bacterium.

Original languageEnglish (US)
Pages (from-to)321-329
Number of pages9
JournalInfection and immunity
Issue number1
StatePublished - Jan 1 2011


ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases

Cite this