Serological studies on murine typhus in field workers of national forest

( Byoungchul Gill ),( Hyun-sul Lim ),( Ji-hyuk Park ),( Jeongmin Lee ),( Nari Shin ),( Yeong Seon Lee ) 대한인수공통전염병학회 2017 창립총회 및 학술대회 초록집 Vol.2017 No.1

Background: Rickettsia species are gram negative, strictly intracellular bacilli that multiply within the cytosol endothelial cells. Rickttsia typhi, a typhus group rickettsia, is the etiologic agent of murine or endemic typhus. R. typhi is transmitted to human primarily by the rat flea, Xenopsylla cheopis, although lice and mites are also potential vectors. In Korea, about 50 cases of this disease has been reported since the first case reported in the 1950s. This surveillance study was conducted to obtain basic data of murine typhus for prevention and control in high-risk population. Materials and Methods: This study included field workers (Yeongrim-dan) in national forest considered as a high-risk population of scrub typhus. The eligible participants were 715 (43.9%) out of 1,629 forestry workers. The sera were collected and then the antibodies specific to R. typhi Wilmington causing murine typhus were titrated using indirect immunofluorescence antibody assay (IFA). As a reference for seroprevalence, 1:256 in IgG or 1:16 in IgM was considered as a single cut-off titer. Results: The seroprevalence showing higher titration than the single cut-off and seroreactivity showing any titration to the single cut-off were 12.4% (89/715) and 26.5% (190/715), respectively. However, the gene for the 16s rRNA of Rickettsia spp. was not detected in any seroprevalence-positive samples. Conclusion: This is the first serological study of murine typhus among forestry workers considered as high-risk population. The high exposure to R. typhi amongst forestry workers suggests that flea-borne spotted fever is an important cause of undifferentiated fever conditions that may not be adequately recognized in Korea. Therefore, continuous surveillance needs to understand the status and to improve the control and prevention of these diseases in high-risk population.

Metabolic Responses to <i>Orientia tsutsugamushi</i> Infection in a Mouse Model

Jung, Jeeyoun,Jung, Youngae,Gill, Byoungchul,Kim, Changhun,Hwang, Kyu-Jam,Ju, Young-Ran,Lee, Hye-Ja,Chu, Hyuk,Hwang, Geum-Sook Public Library of Science 2015 PLoS neglected tropical diseases Vol.9 No.1

<▼1><P>Tsutsugamushi disease is an infectious disease transmitted to humans through the bite of the <I>Orientia tsutsugamushi</I>-infected chigger mite; however, host-pathogen interactions and the precise mechanisms of damage in <I>O. tsutsugamushi</I> infections have not been fully elucidated. Here, we analyzed the global metabolic effects of <I>O. tsutsugamushi</I> infection on the host using <SUP>1</SUP>H-NMR and UPLC-Q-TOF mass spectroscopy coupled with multivariate statistical analysis. In addition, the effect of <I>O. tsutsugamushi</I> infection on metabolite concentrations over time was analyzed by two-way ANOVAs. Orthogonal partial least squares-discriminant analysis (OPLS-DA) showed distinct metabolic patterns between control and <I>O. tsutsugamushi</I>-infected mice in liver, spleen, and serum samples. <I>O. tsutsugamushi</I> infection caused decreased energy production and deficiencies in both remethylation sources and glutathione. In addition, <I>O. tsutsugamushi</I> infection accelerated uncommon energy production pathways (i.e., excess fatty acid and protein oxidation) in host body. Infection resulted in an enlarged spleen with distinct phospholipid and amino acid characteristics. This study suggests that metabolite profiling of multiple organ tissues and serum could provide insight into global metabolic changes and mechanisms of pathology in <I>O. tsutsugamushi</I>-infected hosts.</P></▼1><▼2><P><B>Author Summary</B></P><P>Scrub typhus is an acute febrile illness caused by attacks of <I>Orientia tsutsugamushi</I>-carrying mites, and is the most prevalent febrile illness in the Asia-Pacific region. If not properly treated with antibiotics, patients often develop severe vasculitis that affects multiple organs, and the mortality rate can reach 30%. To explore the pathogenic mechanisms underlying the host-pathogen interaction, we characterized metabolic changes in various organs and the serum of <I>O. tsutsugamushi</I>-infected hosts. After <I>O. tsutsugamushi</I> infection, the host experienced decreased energy production, as well as a severe deficiency in re-methylation sources and glutathione, which impaired purine synthesis, DNA and protein methylation. In addition, abnormal pathways for phosphatidylcholine (PC) biosynthesis and phosphoethanolamine methylation were utilized in the enlarged spleen of <I>O. tsutsugamushi</I>-infected hosts. These results suggested that metabolic profiling could provide insight into global metabolic changes in <I>O. tsutsugamushi</I>-infected hosts, and increase our understanding of the pathogenic mechanisms of <I>O. tsutsugamushi</I>, as well as providing novel therapeutic targets for scrub typhus.</P></▼2>

Immune responses to fusion antigen OT BS56-47 based on the major antigens of Orientia tsutsugamushi causing scrub typhus

( Sangho Choi ),( Hang Jin Jeong ),( Byoungchul Gill ),( Yeong Seon Lee ),( Jeongmin Lee ) 대한인수공통전염병학회 2016 창립총회 및 학술대회 초록집 Vol.2016 No.1

Background: Scrub typhus is an acute, febrile, and potentially fatal mite-borne disease that is caused by infection with Orientia tsutsugamushi. In Korea, the incidence has increased due to environmental changes and increased outdoor activity leading to frequent exposure to chigger mite vectors. Although the infection is treatable with doxycycline and azithromycin, an effective prophylactic vaccine against O. tsutsugamushi would be more favorable for preventing scrub typhus in the endemic areas. Materials and Methods: We combined the immunoreactive regions of 47-kDa outer membrane protein (47-kDa OMP) and 56-kDa type-specific antigen (TSA56) to generate a conventional subunit vaccine expressing recombinant OTBS56-47 (recOTBS56-47) and a DNA vaccine (pOTBS56-47). We evaluated two types of vaccination, intranasal immunization with recOTBS56-47, and Intramuscular immunization with pOTBS56-47 for immunogenicity and efficacy. Results: In mice, intranasal immunization with recOTBS56-47 plus cholera toxin (CT) was the most effective method for the induction of humoral and cell-mediated immune responses; it induced a strong cellular immune response, as demonstrated by a spleen cell proliferation assay, and induced a higher amount of recOTBS56-47-specific antibodies. Intramuscular immunization with pOTBS56-47 alone, or pOTBS56-47 plus adjuvant pmIL-2, induced a low level of humoral immune response. Conclusion: OTBS56-47 is an attractive candidate for developing a prophylactic vaccine against scrub typhus caused by O. tsutsugamushi. This work was supported by an intramural fund (2013-NG52001-00) by research of Korea Centers for Disease Control and Prevention.

A Recombinant 47-kDa Outer Membrane Protein Induces an Immune Response against <i>Orientia tsutsugamushi</i> Strain Boryong

Choi, Sangho,Jeong, Hang Jin,Hwang, Kyu-Jam,Gill, Byoungchul,Ju, Young Ran,Lee, Yeong Seon,Lee, Jeongmin Allen Press, etc 2017 The American journal of tropical medicine and hygi Vol.97 No.1

<P><B>Abstract.</B></P><P>We investigated the 47-kDa outer membrane protein (OMP), which is a periplasmic serine protease and an antigenic major surface protein of <I>Orientia tsutsugamushi</I>, as a vaccine candidate. We developed a conventional subunit vaccine expressing recombinant 47-kDa OMP (rec47) and a DNA vaccine (p47). In mouse immunization experiments, intranasal immunization with rec47 alone or with rec47 plus heat-labile enterotoxin B subunit from <I>Escherichia coli</I> or plus cholera toxin (CT) as adjuvants induced a higher amount of rec47-specific antibodies than intramuscular immunization with p47 alone or with p47 plus pBOOST2-samIRF7/3 (pB) as adjuvant. Moreover, the combination of rec47 and CT induced a strong cellular immune response to 47-kDa OMP, as demonstrated by a spleen cell proliferation assay, and also induced Th1- and Th2-type cytokine production, as demonstrated by a cytokine enzyme-linked immunosorbent assay. Intranasal immunization with rec47 plus CT was the most effective method for the induction of humoral and cell-mediated immune responses. Furthermore, relatively strong protection against homologous <I>O. tsutsugamushi</I> strain Boryong challenge was observed in mice immunized with rec47 plus CT. Therefore, 47-kDa OMP is an attractive candidate for developing a prophylactic vaccine against scrub typhus by <I>O. tsutsugamushi</I> infection.</P>

Protective Immunity of 56-kDa Type-Specific Antigen of Orientia tsutsugamushi Causing Scrub Typhus

( Sang Ho Choi ),( Hang Jin Jeong ),( Young Ran Ju ),( Byoungchul Gill ),( Kyu Jam Hwang ),( Jeong Min Lee ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.12

Scrub typhus, caused by infection with Orientia tsutsugamushi, is a mite-borne zoonotic disease endemic to the Asian-Pacific region. In Korea, the incidence of this disease has increased with climate changes, and over 10,000 cases of infection were reported in 2013. Although this infection is treatable with antibiotics such as doxycycline and azithromycin, an effective prophylactic vaccine against O. tsutsugamushi would be more desirable for preventing scrub typhus in endemic areas. In this study, we investigated the 56-kDa type-specific antigen (TSA56), which is a major outer membrane protein of O. tsutsugamushi, as a vaccine candidate. Intranasal immunization of recombinant TSA56 (rec56) induced a higher level of TSA56- specific IgG than that induced by intramuscular immunization of tsa56-expressing DNA (p56). Both types of immunization induced a cell-mediated immune response to TSA56, as demonstrated by the splenic cell proliferation assay. Mice immunized with p56, followed by rec56 plus heat-labile enterotoxin B subunit from E. coli, had a stronger protection from a homologous challenge with the O. tsutsugamushi Boryong strain than with other combinations. Our preliminary results suggest that an effective human vaccine for scrub typhus can include either recombinant TSA56 protein or tsa56-expressing DNA, and provide the basis for further studies to optimize vaccine performance using additional antigens or different adjuvants.

Annual Fluctuation in Chigger Mite Populations and Orientia Tsutsugamushi Infections in Scrub Typhus Endemic Regions of South Korea

Seong Yoon Kim,Jong Yul Roh,Bong-Gu Song,추혁,Won Il Park,이희일,E-Hyun Shin,조신형,Byoungchul Gill 질병관리본부 2019 Osong Public Health and Research Persptectives Vol.10 No.6

Objectives: Chigger mites are vectors for scrub typhus. This study evaluated the annual fluctuations in chigger mite populations and Orientia tsutsugamushi infections in South Korea. Methods: During 2006 and 2007, chigger mites were collected monthly from wild rodents in 4 scrub typhus endemic regions of South Korea. The chigger mites were classified based on morphological characteristics, and analyzed using nested PCR for the detection of Orientia tsutsugamushi. Results: During the surveillance period, the overall trapping rate for wild rodents was 10.8%. In total, 17,457 chigger mites (representing 5 genera and 15 species) were collected, and the average chigger index (representing the number of chigger mites per rodent), was 31.7. The monthly chigger index was consistently high (> 30) in Spring (March to April) and Autumn (October to November). The mite species included Leptotrombidium pallidum (43.5%), L. orientale (18.9%), L. scutellare (18.1%), L. palpale (10.6%), and L. zetum (3.6%). L. scutellare and L. palpale populations, were relatively higher in Autumn. Monthly O. tsutsugamushi infection rates in wild rodents (average: 4.8%) and chigger mites (average: 0.7%) peaked in Spring and Autumn. Conclusion: The findings demonstrated a bimodal pattern of the incidence of O. tsutsugamushi infections. Higher infection rates were observed in both wild rodents and chigger mites, in Spring and Autumn. However, this did not reflect the unimodal incidence of scrub typhus in Autumn. Further studies are needed to identify factors, such as human behavior and harvesting in Autumn that may explain this discordance.