Learn More
Two specific and sensitive polymerase chain reaction (PCR) assays were developed to detect and quantitate Orientia tsutsugamushi, the agent of scrub typhus, using a portion of the 47-kD outer membrane protein antigen/ high temperature requirement A gene as the target. A selected 47-kD protein gene primer pair amplified a 118-basepair fragment from all 26(More)
A truncated recombinant 56-kDa outer membrane protein of the Karp strain of Orientia tsutsugamushi (Kp r56) was evaluated in cynomolgus monkeys (Macaca fascicularis) for immunogenicity and safety as a vaccine candidate for the prevention of scrub typhus. This recombinant antigen induced strong humoral and cellular immune responses in two monkeys and was(More)
The aim of this study was to survey the bacterial diversity of Amblyomma maculatum Koch, 1844, and characterize its infection with Rickettsia parkeri. Pyrosequencing of the bacterial 16S rRNA was used to determine the total bacterial population in A. maculatum. Pyrosequencing analysis identified Rickettsia in A. maculatum midguts, salivary glands, and(More)
The 56-kD outer membrane protein of Orientia tsutsugamushi has previously been shown to be the immunodominant antigen in scrub typhus infections. Its gene was cloned into the DNA vaccine vector pVR1012 as a vaccine candidate (pKarp56). The in vitro expression of this 56-kD antigen by pKarp56 was confirmed in tissue culture by an indirect fluorescence assay(More)
The Lone Star tick, Amblyomma americanum, is endemic to the southeastern United States and capable of transmitting pathogenic diseases and causing non-pathogenic conditions. To remain firmly attached to the host, the tick secretes a proteinaceous matrix termed the cement cone which hardens around the tick's mouthparts to assist in the attachment of the tick(More)
Orientia tsutsugamushi is the etiological agent of scrub typhus, an acute, mite-borne, febrile illness that occurs in the Asia-Pacific region. Historically, strain characterization used serological analysis and revealed dramatic antigenic diversity. Eyeing a recommendation of potential vaccine candidates for broad protection, we review geographic diversity(More)
We compared the performance of 2 commercially available dipstick assays, 2 enzyme-linked immunosorbent assays (ELISAs), and an indirect immunofluorescent antibody (IFA) assay for the diagnosis of scrub typhus, using the indirect immunoperoxidase (IIP) test as the reference standard. The dipstick assays were the Integrated Diagnostics (Baltimore, MD)(More)
Two scrub typhus outbreaks occurred among U.S. Marines training at Camp Fuji, Japan, between October 25 and November 3, 2000 and October 17 and November 30, 2001. Nine cases in approximately 800 Marines in 2000 and eight cases in approximately 900 Marines in 2001 (approximate attack rates = 1.1% and 0.9%, respectively) reported with signs and symptoms of(More)
Rickettsia prowazekii, the causative agent of epidemic typhus, has been responsible for millions of human deaths. Madrid E is an attenuated strain of R. prowazekii, while Breinl is a virulent strain. The genomic DNA sequence of Madrid E has recently been published. To study the genomic variations between Madrid E (reference) and Breinl (test) DNAs,(More)
We evaluated the diagnostic accuracy of two broadly reactive rapid immunochromatographic tests (ICTs) for detection of IgM and IgG against Orientia tsutsugamushi by using archived acute-phase serum samples from 102 patients with laboratory-confirmed scrub typhus, and from 62 archived serum samples from patients with other causes of fever as a negative(More)