Role of Type I Interferon during Bacterial Infection

Type 1 Interferons (T1 IFN) play a pivotal role in innate immune responses against viral infection. Recently, this anti-viral cytokines are shown to be induced during bacterial infections via activation of various pattern recognition receptors (PRRs) including Toll-like receptors, RIG-I-like receptors, or NOD-like receptors. Signaling mediators such as MyD88, TRIF, MAVS, STING, or RIP2 of the receptor signaling pathways are also involved in T1 IFN responses depending on the bacterial species and their ligands. However, role of T1 IFN in anti-bacterial immunity is still obscure and its effect on immunological pathogenesis during bacterial infection has been controversial. It has been reported that T1 IFN could provide protective effect on several bacterial infections but it also aggravates pathogenic situation during some intracellular pathogens or secondary bacterial infection after respiratory viral infection. Here, we summarize recent findings how T1 IFN is induced by various bacterial pathogens and discuss the potential effect of T1 IFN responses on immune responses against bacterial infection.

Improvement of the Diagnostic Sensitivity of Scrub Typhus Using a Mixture of Recombinant Antigens Derived from Orientia tsutsugamushi Serotypes

Diagnosis of scrub typhus is difficult because its symptoms are very similar to other acute febrile illnesses, such as leptospirosis, murine typhus, and other viral hemorrhagic fevers. To differentiate scrub typhus from other acute febrile diseases, a rapid and reliable serological diagnosis is important. We have developed a chimeric recombinant antigen cr56 and two other recombinant antigens, r21 and kr56, from various serotypes of Orientia tsutsugamushi. They were tested for the detection of antibodies against O. tsutsugamushi in the patient's serum samples using enzyme-linked immunosorbent assay (ELISA) and dot-blot analyses. As of conventional immunofluorescence assay (IFA), when the mixture of these three recombinant antigens was used, both sensitivity and specificity of the recombinant antigens were increased up to 98% in IgM and IgG at ELISA and dot blotting. Additionally, both sensitivity and specificity by detection of IgM and IgG antibodies at rapid diagnostic test (RDT), using the mixture of three antigens and gold conjugated antibodies, were 99%. Our results suggest the use of mixture of these recombinant antigen proteins in ELISA or RDT is suitable as a diagnostic test for scrub typhus.

A Case of Tsutsugamushi Disease after Traveling to the Philippines / 감염과화학요법

Infectious diseases imported from other countries have increased as more and more Koreans are going abroad for various purposes. Tsutsugamushi disease from other endemic area such as Southeast Asia is important, because it can occur in any season and eschar may be absent. We report a case of imported tsutsugamushi disease acquired in the Philippines. A patient presented with fever, headache, and maculopapular skin rash. However, eschar was absent. Polymerase chain reaction (PCR) for 56-kDa gene of Orientia tsutsugamushi using buffy coat was positive. Serum indirect immunofluorescent antibody assay was initially negative but became positive with a titer of 1:320 at follow-up. Sequencing analysis revealed the strain to be 100% identical to the TW73R strain identified in Taiwan. After the patient received doxycycline, body temperature normalized in 12 hours. Tsutsugamushi disease is one of the differential diagnoses that should be included for patients with fever who have recently returned from Southeast Asian countries. PCR for O. tsutsugamushi using patient's buffy coat was useful for early diagnosis.

A Case of Tsutsugamushi Disease after Traveling to the Philippines / 감염과화학요법

Infectious diseases imported from other countries have increased as more and more Koreans are going abroad for various purposes. Tsutsugamushi disease from other endemic area such as Southeast Asia is important, because it can occur in any season and eschar may be absent. We report a case of imported tsutsugamushi disease acquired in the Philippines. A patient presented with fever, headache, and maculopapular skin rash. However, eschar was absent. Polymerase chain reaction (PCR) for 56-kDa gene of Orientia tsutsugamushi using buffy coat was positive. Serum indirect immunofluorescent antibody assay was initially negative but became positive with a titer of 1:320 at follow-up. Sequencing analysis revealed the strain to be 100% identical to the TW73R strain identified in Taiwan. After the patient received doxycycline, body temperature normalized in 12 hours. Tsutsugamushi disease is one of the differential diagnoses that should be included for patients with fever who have recently returned from Southeast Asian countries. PCR for O. tsutsugamushi using patient's buffy coat was useful for early diagnosis.

Immunogenicity and Safety of Oral Live Attenuated Salmonella typhi Vaccine / 감염과화학요법

BACKGROUND: This study is aimed at evaluating immunogenicity by measuring immunoglobulin A (IgA) seroconversion rate through common mucosal immune system and adverse reactions after vaccination of oral live attenuated Salmonella typhi (S. typhi) Ty21a vaccine in Korean population. METHODS: A commercially available oral live attenuated vaccine of S. typhi strain Ty21a (Zerotyph(r) capsule, Boryung Biopharma Co., Seoul, Korea) was given to volunteers; children above 6 years, adolescents, and adults who have never infected with S. typhi nor received S. typhi vaccination. The vaccines were given in three doses, with two day interval between the doses. Seroconversion was determined by ELISPOT (enzyme-linked immunospot) assay. Adverse reactions after vaccination were evaluated in 12 institutions by direct interviewing with vaccinees. RESULTS: A total of 93 volunteers for evaluation of seroconversion were enrolled. Seroconversion rate in the the below 16 year-old group was 73.8% (31/42) and that of over 16 year-old group was 86.3% (44/51), which was not statistically different. Adverse reaction were found in 8.6% (40/465). Gastrointestinal symptoms were most common (6.5%, 30/465). Adverse reactions were found in 5.2% (24/465) after 1st administration, 4.5% (21/462) after 2nd, and 2.6% (12/461) after 3rd. Frequency of adverse reactions was significantly higher after 1st administration (P<0.05). CONCLUSION: Oral live attenuated S. typhi vaccine, Zerotyph(r) capsule, had good immnuogenicity and safety through intestinal immune system.

Immunogenicity and Safety of Oral Live Attenuated Salmonella typhi Vaccine / 감염과화학요법

BACKGROUND: This study is aimed at evaluating immunogenicity by measuring immunoglobulin A (IgA) seroconversion rate through common mucosal immune system and adverse reactions after vaccination of oral live attenuated Salmonella typhi (S. typhi) Ty21a vaccine in Korean population. METHODS: A commercially available oral live attenuated vaccine of S. typhi strain Ty21a (Zerotyph(r) capsule, Boryung Biopharma Co., Seoul, Korea) was given to volunteers; children above 6 years, adolescents, and adults who have never infected with S. typhi nor received S. typhi vaccination. The vaccines were given in three doses, with two day interval between the doses. Seroconversion was determined by ELISPOT (enzyme-linked immunospot) assay. Adverse reactions after vaccination were evaluated in 12 institutions by direct interviewing with vaccinees. RESULTS: A total of 93 volunteers for evaluation of seroconversion were enrolled. Seroconversion rate in the the below 16 year-old group was 73.8% (31/42) and that of over 16 year-old group was 86.3% (44/51), which was not statistically different. Adverse reaction were found in 8.6% (40/465). Gastrointestinal symptoms were most common (6.5%, 30/465). Adverse reactions were found in 5.2% (24/465) after 1st administration, 4.5% (21/462) after 2nd, and 2.6% (12/461) after 3rd. Frequency of adverse reactions was significantly higher after 1st administration (P<0.05). CONCLUSION: Oral live attenuated S. typhi vaccine, Zerotyph(r) capsule, had good immnuogenicity and safety through intestinal immune system.

Seroprevalence to Coxiella burnetii in Patients with Acute Febrile Episodes during 1993

Coxiella burnetii is the etiological agent of Q fever, that may occur either acutely or the chronically. To understand the seroepidemiological patterns of C. burnetii infection in Korea, we examined a total of 3,178 sera from patients with acute febrile episodes by using indirect immunofluorescence assay (IFA) for detectable antibodies to C. burnetii and other eight rickettsial antigens. The IFA seropositivity>or=1:20 for C. burnetii phase II was 11.5% (368 out of 3,178 sera). The co-existence of antibodies to other rickettsial antigens was found in 216 out of the 368 positive sera. Thirty-seven point five percent (n=138) had antibodies to R. tsutsugamushi (cutoff>or=1:20), 16% (n=59) to Ehrlichia sennetsu, 14.9% (n=55) to Rickettsia typhi, 13.5% (n=50) to R. akari, 11.4% (n=42) to R. japonica, 8.9% (n=33) to R. prowazekii, 7.6% (n=28) to R. sibirica, and 6.7% (n=25) to R. conorii by IFA, respectively. These results are consistent with previous reports documenting diverse serum cross-reactivity in chronic Q fever. Therefore we excluded the samples that reacted to other rickettsial antigens at same or higher titers than to C. burnetii, resulting in the seropositive rate of 4.1%. The serological prevalence was 2% (n=64) when the conventional cut-off titer of 1:80 was used. Our results suggest that infections with C. burnetii are more prevalent than expected previously and should be differentially diagnosised for febrile illness occurring after exposure to ticks or other vectors.

Serological Analysis of Ehrlichiosis in Korean from 1990 to 1992

Ehrlichia sennetsu is the causative agent of human Sennetsu ehrlichiosis. Ehrlichiosis is an acute and occasionally chronic infectious disease caused by obligate intracellular bacteria in the family Rickettsiaceae. To understand the seroepidemiological patterns of ehrlichiosis in Korea, a total of 2,625 patients with acute febrile episode reported from 1990 to 1992 were surveyed using an indirect fluorescent antibody assay (IFA). The result was as follows. Seropositivity for ehrlichiosis was 3.23% by excluding highly cross-reacted sera with other rickettsial antigens. Sera reacted to E. sennetsu showed the cross reaction with other rickettsia as in the order of R. typhi 49.6%, R. conorii 31.6%, R. japonica 28.1%, C. burnetii 26.4%, R. sibirica 25.8%, O. tsutsugamushi 25.8%, R. akari 25.4%, and R. prowazekii 25.4%. Sexual difference in the seropositivity was not noted. The age groups of fifties and under the tenth showed higher prevalence than others. Seropositivity was most prevalent in July and August. As for regional distribution, Chonbuk (10.5%) showed the highest seropositive rate. Geographical distribution of the seropositivity covered most area except Cheju province in Korea.

Serological Analysis of Epidemic Typhus in Korea from 1990 to 1992

No abstract available.

Serological Analysis of Endemic Typhus in Korea from 1990 to 1992

No abstract available.

Scrub Typhus in a Pregnant Woman: No Evidence of Intrauterine Infection / 감염

Pregnancy with scrub typhus is a rare condition. A 30-year-old woman was infected with scrub typhus at the 35th week of gestation. She was treated successfully with azithromycin, and delivered her baby uneventfully. The baby developed no signs for scrub typhus, and thrived well. IgM antibodies to O. tsutsugamushi were undetectable in the baby's sera, and titers of IgG antibodies did not rise. The polymerase chain reaction of the cord blood for O. tsutsugamushi was also negative. We concluded that transplacental infection did not occur in this pregnant woman.

Increased expression of adhesion molecules on human umbilical vein endothelial cells by Orientia tsutsugamushi infection

Scrub typhus is caused by Orientia tsutsugamushi characterized by fever, headache, lymphadenopathy and eschar formation. Infiltration of inflammatory cells around blood vessels and within the affected organs is known to be pathologic hallmark of the scrub typhus. Recently, expression of adhesion molecules on vascular endothelial cells was implicated as an important pathogenic mechanism in rickettsial disease. This study was performed to examine the expression of adhesion molecules and to investigate its role in the pathogenesis of O. tsutsugamushi infection. The expression of adhesion molecules on human umbilical vein endothelial cells (HUVEC) was measured by flow cytometry and indirect immunofluorescence. Expression of E-selectin, ICAM-1 and VCAM-1 was significantly increased 4 hours after the infection and persisted at least for 24 hours. Expression of those molecules was not induced by killed O. tsutsugamushi. Adhesion of polymorphonuclear cells and mononuclear cells to HUVEC was increased after the infection with O. tsutsugamushi. In conclusion, adhesion molecules are expressed on HUVEC during the infection of live O. tsutsugamushi and those molecules can contribute to the infiltration of inflammatory cells during the infection.

47kDa Protein of Orientia tsutsugamushi Do a Critical Role in Invasion to Eucaryotic Cells by Binding to Cell Surface Heparan Sulfate

No Abstract Available.

Gene Cloning of the Epstein-Barr Virus (EBV) Antigen Reactive with the Serum from EBV-infected Patients / 감염

BACKGROUND: Epstein-Barr virus (EBV) is causative agent of infectious mononucleosis and nasopharyngeal carcinoma and associated with Burkitt lymphoma and other tumors. The recombinant protein is needed for the rapid and sensitive serodiagnosis of EBV infection. METHODS: EBV gene encoding the protein reactive with the sera of EBV-infected patient was cloned and characterized with lambda gt11 expression library of cDNA of EBV B95-8 strain. RESULTS: The recombinant proteins from clone 12, 15 and 21 were expressed as 120, 118, 160 kDa-usion protein with beta-galactosidase, respectively, which were reactive with IgG anti-EBV antibody-positive sera, but not with anti-EBV antibody-negative sera. A homology search of the DNA sequence of the cloned gene with EBV B95-8 sequences revealed that those were located at 61716~62087, 61898~62085, and 102128~103158, respectively. These positions correspond to BFRF3, BFRF3, and BZLF1, respectively, which were reported as immunogenic protein which evoked strong and longstanding antibody response and had no sequence homology with the proteins of other herpesviruses. All the patients' sera were reactive with clone 12 protein, but only 5 out of 9 patients' sera were reactive with clone 21 protein. CONCLUSION: Clone 21 protein expressing BFRF3 fragment was immunoreactive in patient sera from natural EBV infection and was regarded as useful candidate for the serodiagnosis of EBV infection.

Infectivity of Orientia tsutsugamushi to Various Eukaryotic Cells and Their Cellular Invasion Mechanism

Orientia tsutsugamushi is obligate intracellular bacterium that grows within the cytoplasm of the eukaryotic host cells. Therefore capability of the attachment, entry into the host cell and intracellular survival should be critical process for oriential infection. In this study we investigated the cellular invasion mechanism of Orientia tsutsugamushi and the role of transmembrane heparan sulfate proteoglycan, which binds diverse components at the cellular microenvironment and is implicated as host cell receptors for a variety of microbial pathogens. First of all Orientia tsutsugamushi can invade a wide range of nonprofessional phagocytic cells including fibroblast, epithelial cells a#nd endothelial cells of various host species, including B and T lymphocytes. Thus, it was postulated that the attachment of O. tsutsugamushi requires the recognition of ubiquitous surface structures of many kinds of host cells. Treatments with heparan sulfate and heparin inhibited the infection of Orientia tsutsugamushi in dose-dependent manner for L cell, mouse fibroblast, whereas other glycosaminoglycans such as chondroitin sulfate had no effect. Collectively, these findings provide strong evidence that initial interaction with heparan sulfate proteoglycan is required for the oriential invasion into host cells.

Identification of Mycobacterium avium complex ( MAC ) clinical Strains to a Species Level by Sequencing and PCR - SSCP Analysis of rpoB DNA

A recent study showed that comparative sequence analysis of rpoB DNAs could reveal natural relationships in genus Mycobacterium [J Clin Microbiol. 37 (6). 1999]. rpoB DNAs showed interspecies variation and intraspecies conservation, Based on these data, we developed polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) protocols which enable species differentiation in genus Mycabacterium. When this assay was applied to 24 clinical isolates identified as M. avium complex (MAC) by biochemical test, these were successfully differentiated into M. avium and M. intracellulare. These results were concordant with those obtained by 16s rDNA analysis. It is the first report that PCR-SSCP analysis of rpoB DNA could be used for species differentiation of MAC strains.

Laboratory-Acquired Infections with Hantavirus at a Research Unit of Medical School in Seoul, 1996 / 예방의학회지

BACKGROUND: In April 6, 1996, a male researcher who has worked at a research unit at the Basic Research Building of Seoul National University(SNU) College of Medicine admitted to SNU Hospital due to persistent fever. He was diagnosed serologically as hemorrhagic fever with renal syndrome(HFRS). Another female researcher in the same unit was also diagnosed as HFRS at the same hospital several days later. Epidemic investigation of HFRS was conducted to determine the magnitude of the problems since these two cases were strongly suspected to have laboratory-acquired infections of HFRS. METHODS: All researchers and employees working at the Basic Research Building(BRB) of SNU College of Medicine as of April 1, 1996 were recruited for the study. Information on symptoms of HFRS and history of contact to experimental animals were collected by self-administered questionnaires and serological tests among study subjects were also conducted by indirect immunofluorescent antibody(IFA) to hantavirus. The experimental animals were also serologically tested for infection with hantavirus by IFA. RESULTS: Among 218 surveyed, six researchers and an animal caretaker had hantavirus antibodies above 1:20 in IFA titer. Five of seven sero-positive subjects had antibodies above 1:640 in IFA titer and had shown clinical symptoms compatible to HFRS during Jan. 1 to Apr. 20, 1996. The sero-positive persons had handled animals more frequently than sero-negative persons (OR, 19.68; 95% CI, 1.11 - 350.40) and handling animals at the animal quarter at School of Public Health(SPH) had shown consistently higher risk to get infected with hantavirus irrespective of types of animals handled (OR, 4.90 - 6.37). Sero-positivity of rats of the aniamal quarter at BRB was 30-60%, whereas 80% of rats at SPH tested were shown sero-positivity. CONCLUSION: There was a epidemic of HFRS in research units of a medical school during the period from Jan. through Apr. Further investigation is needed to determine the extent and the mode of transmission of the laboratory-acquired infection with hantavirus in other research facilities.

Seroepidemiological Survey of Hemorrhagic Fever with Renal Syndrome in Korea , 1994 - 1996

To understand the seroepidemiological patterns of haemorrhagic fever with renal syndrome in Korea, a nation-wide survey collaborated with fourteen clinics was carried out from 1994 to 1996. Sera of 4,547 patients with acute febrile episodes were tested by indirect immunofluorescent antibody test and the seroepidemiological analysis including sex, age, seasonal and regional distributions were performed. According to the results obtained in this study, the epidemiological characteristics of haemorrhagic fever with renal syndrome in Korea were summarized as follows: 1. Seropositive rate of hemorrhagic fever with renal syndrome among the patients with acute febrile episodes was 6.4% by the cut-off point of 1:40. 2. Among the seropositives, male outnumbered female and the ratio of males to females was 2.0:1.0. 3. Seventy six % of the seropositive patients were 21-60 years old. 4. The number of seropositive cases increased from October and reached maximum in December and began to decrease gradually from January. 5. The geographical distribution of the seropositives cover most areas including Cheju province in Korea.

Antigenicity of the G2 Glycoprotein in Cell - Mediated Immune Response Against Hantanvirus Infection

Hemorrhagic fever with renal syndrom is an acute febrile disease which is caused by Hantanvirus and several other viruses that belong to the genus Hantavirus. Gl and G2 glycoproteins of Hantanvirus have been thought to be involved in protective immunity against Hantanvirus infection. In this study, the antigenicity of G1 and G2 glycoproteins in cell mediated immune response was investigated. When peripheral blood mononuclear cell fraction from recovered hemorrhagic fever with renal syndrome patient was cultivated with a recombinant protein containing amino-terminal 78 amino acids of G2 glycoprotein, these cells were activated to proliferate and secreted significant amount of interleukin-2 and interferon-r. These results suggest that T cell epitope exists in the amino-terminal region of G2 glycoprotein.

Safety and Immunogenicity of a Pseudomonas aeruginosa Outer Membrane Protein Vaccine(CFC-101) : a Phase I/IIa Clinical Trial / 감염

BACKGROUND: We developed a Pseudomonas aeruginosa outer membrane protein(OMP) vaccine, CFC-101, and the prophylactic efficacy of which has been demonstrated in animal models. In order to evaluate the safety and immunogenicity of the P. aeruginosa vaccine, we carried out a phase I/IIa clinical trial in healthy male volunteers. METHODS: Groups of eight volunteers, including two placebo subjects, were vaccinated intramuscularly with three doses of 0.25, 0.5 or 1.0 mg of the vaccine at one week intervals. Signs of systemic and local reactions observed after vaccination were recorded for each vaccinee for 5 days. Physical examinations were performed on days 0, 1, 7, 8, 14, 15, 21, and 42, and clinical laboratory tests were done on days 0, 3, and 21. Blood samples for assay of serum antibody levels were obtained up to 42 days after the first vaccination. RESULTS: The vaccine was generally well tolerated by all vaccinees, showing no significant side effects. In the three dosage groups, all vaccinees, except one receiving the 0.25 mg dose, showed significant elevation in serum IgG antibody titers against the vaccine proteins, indicating 100% seroconversion in 0.5 and 1.0 mg groups. The human antibodies induced by the vaccine were specific for P. aeruginosa OMPs, as confirmed by western blot analysis and immunoprecipitation assays. The capacity of the human antisera to enhance opsonophagocytic killing activity by polymorphonuclear leukocytes and to confer protection against P. aeruginosa infections indicates that the antibodies elicited by the vaccine have protective efficacy. CONCLUSION: We conclude that the P. aeruginosa OMP vaccine is safe and effective for human use and its optimal dose to be 0.5 or 1.0 mg.