Address for correspondence: Marina E. Eremeeva, Viral and Rickettsial Zoonoses Branch, National Center for Infectious Diseases, 1600 Clifton Road NE, Atlanta, GA 30333. Voice: 404-639-4612; fax: 404-639-4436.
MEremeeva{at}cdc.gov
Ann. N.Y. Acad. Sci. 990: 468-473 (2003).
The pine vole,
Microtus pinetorum, was evaluated as a laboratory
animal model for infection with
Rickettsia rickettsii. Voles
demonstrated signs of acute disease, and 45% of infected animals
died following intraperitoneal infection with 3
x 10
6 plaque
forming units of
R. rickettsii. Spleen, liver, kidney, lung,
brain, testes and blood were analyzed for rickettsial burden
by a quantitative PCR assay. The distribution of rickettsiae
in tissues during the course of infection was determined by
immunohistochemical staining and pathological changes in tissues
were correlated with the clinical severity of infection. Quantitative
RT-PCR assays were designed to measure the mRNA levels of the
antioxidant enzyme genes for catalase, glutathione peroxidase,
glutathione reductase, heme oxygenase, Cu-Zn superoxide dismutase
(SOD) and Mn-SOD, and 2 housekeeping genes, actin and glyceraldehyde
phosphate dehydrogenase. Tissues from acutely ill animals on
days 2 to 6 of infection, convalescent animals, and uninfected
control animals were studied. The number of transcripts of each
enzyme gene was determined and compared to the degree of rickettsial
infection present. These studies demonstrate that the pine vole
is a valuable experimental model for studying infection with
R. rickettsii. Our results provide the first experimental evidence
that
R. rickettsii causes alteration(s) of the anti-oxidant
system
in vivo.
