Activation of Innate Immune System During Viral Infection: Role of Pattern-recognition Receptors (PRRs) in Viral Infection

Innate immunity and adaptive immunity are two major immune responses against pathogens. Innate immunity is responsible for the immediate immune response to pathogens. Pattern-recognition receptors (PRRs) play an important role in innate immune response. PRRs recognize regular patterns of molecule structure known as pathogen-associated molecular patterns (PAMPs). Among the PRRs, Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), and DNA-dependent activator of interferon regulatory factors (DAI) display key roles in response to viral infections. This article reviews how viral infections activate PRR-PAMP signal pathways and how viruses evade immune responses elicited by PRR signal pathways.

Expression of Plus- and Minus-strand Viral RNA in Coxsackievirus B3-Infected A/J Mice

In order to investigate the implication of viral replication in acute, subacute, and chronic infections of coxsackievirus B3 (CVB3), we examined the histopathological changes and plus- and minus-strand viral RNA dynamics in heart, pancreas, brain, and liver of CVB3-infected A/J mice. Mice were inoculated intraperitoneally with CVB3 and sacrificed on 1, 2, 3, 4, 7, 10, 14, 21, 30, 60, and 90 days post infection (p.i.). Plus- and minus-strand viral RNAs in the organs were quantitated and the organs were additionally evaluated histopathologically for inflammation. No inflammatory infiltrates were observed in the liver, brain, and heart. In contrast, massive lymphocyte infiltration and fat replacement were shown in the pancreas with loss of acinar cells. Both plus- and minus-strand viral RNA levels were detected by 21 days p.i. in heart, 90 days p.i. in pancreas, 4 days p.i. in liver, and 10 days p.i. in brain. The plus-strand RNA was found at least fifty fold higher than the minus-strand RNA by 4 days p.i. in heart and pancreas and by 3 days p.i. in liver. The plus- to minus-strand RNA ratio in brain was found less than 1:20. Our data indicate that viral replication was actively occurred in heart, pancreas, and liver during acute CVB3 infection, whereas viral replication was limited in brain. Furthermore, chronic persistent viral RNA was observed in pancreas. In conclusion, CVB3 at low dose of virus induces severe pancreatitis but marginal or no inflammatory changes in the heart, liver, and brain.

Characterization of Enteroviruses Isolated from Patients with Aseptic Meningitis

Enteroviruses (EVs) are human pathogens that cause a wide variety of clinical illnesses. The spectrum of the diseases ranges from a mild febrile illness to severe diseases such as meningitis or myocarditis. In the present study, we have used a reverse transcription-polymerase chain reaction method to detect EVs from patients with aseptic meningitis followed by typing of the EVs after HeLa cell culture isolation. In addition, twelve reference strains and the six clinical isolates of EVs were infected to neonatal rat cardiocytes and the viability of infected cells was measured by MTT assay. Marked inhibition of cell proliferation was observed in the cardiocytes cultures infected with coxsackievirus (CV) B1, CVB4, and CVB5, and two wild strains, whereas mild inhibition was observed from those infected with CVB2, CVB3, echoviruses 6, 7, 11, 22, 25, and 30. Recombinant plasmid containing full-length cDNA genome of the cardiovirulent wild strain was successfully constructed and its complete nucleotide sequence was determined. The genome showed characteristics of enteroviruses. The RNA genome was 7,391 nucleotides in length, with a 5'-nontranslating region (742 nucleotides) followed by an open reading frame (encoding a 2,182 amino acid polyprotein) and a 3'-nontranslating region (100 nucleotides) and polyadenylated tail. The predicted amino acid sequences of the polyprotein showed 89~95% homology with those of reference coxsackievirus strains (CVB1-5).

Rapid Detection and Identification of Human Respiratory Syncytial Virus, Human Parainfluenza Virus Type 1, 2 and 3 by Single-tube Multiplex Reverse Transcription Polymerase Chain Reaction

Laboratory diagnosis of respiratory viral infection has traditionally been based upon virus isolation and/or viral antigen identification. Recently, more sensitive and specific nucleic acid detection methods by reverse transcription- polymerase chain reaction (RT-PCR) have been developed, however, conventional RT-PCR can identify only a single suspected virus. To identify the causative agents which belong to Paramyxoviridae of respiratory virus infections, we have developed a single-tube multiplex RT-PCR using four primer sets which can amplify respiratory syncytial virus and parainfluenza virus type 1, 2 and 3 simultaneously. Assay sensitivity of single-tube multiplex RT-PCR allowed a detection in the range of 3~500 TCID50 and there were no cross amplification among other respiratory viral agents based on the test using reference virus stocks. The single-tube multiplex RT-PCR was able to directly detect viruses in respiratory specimens, with virus being detected 11 of 80 samples as compared to 9 of 80 samples detected by indirect immunofluorescence or antigen detection following shell vial culture. This result suggests that the single-tube multiplex RT-PCR can be established as a more sensitive and rapid diagnostic application than shell vial assay for the detection of respiratory infection of Paramyxoviridae.

Molecular Analysis of Protease and Reverse Transcriptase in an AIDS Patient with HAART - Failure

No abstract available.

Sequence Varation of 5(1) Nontranslating Region of Enterovirus Isolated from Patients with Aseptic Meningitis

No abstract available.

A Prospective Multicenter Study on the Etiological Analysis of Community-Acquired Pneumonia in Adult Patients in Korea: Detection of Mycoplasma pneumoniae and Chlamydia pneumoniae Infections / 감염

BACKGROUND: The purpose of this study is to develop rapid and sensitive method to detect M. pneumoniae and C. pneumoniae. In addition, we prospectively investigate the prevalence of M. pneumoniae and C. pneumoniae infections in community-acquried pneumonia. METHODS: The nasopharyngeal aspirates were collected from July 1997 to April 2000. PCR or nested PCR techniques were used to detect causative agents. RFLP and nucleotide sequence analysis were performed to study molecular epidemiology. Furthermore, feasibility of one-step technique to detect two microorganisms was tested by use of multiplex PCR. RESULTS: Of 250 clinical specimens, 23 (9.2%) specimens were positive for M. pneumoniae and 33 (13.2%) for C. pneumoniae, including one dual-infected specimen. Most M. pneumoniae infection occurred during the colder months of the year. C. pneumoniae infection was predominently found between December to February. CONCLUSION: The result indicate that M. pneumoniae and C. pneumoniae infections are frequently found from patients with community-acquired pneumoniae.

Detection and Characterization of Enteroviral RNA in Paraffin-embedded Heart Tissues form Patients with Dilated Cardiomyopathy

The aim of this study was to investigate viral etiology in dilated cardiomyopathy (DCM) by polymerase chain reaction (PCR) or nested reverse tanscription PCR (RT-PCR), and characterize the enteroviral RNA presented in the clinical specimens. Twenty-eight paraffin-embedded heart tissue samples were assayed to detect cytomegalovirus, herpes simplex virus type 1, type 2, parvovirus, adenovirus, and enterovirus (EV) with each specific primer. Of these 28 patients (mean age: 27, M: 24, F: 4), 26 were histologically diagnosed as DCM and 2 as myocardial infarction (MI). Nested RT-PCR detected enteroviral RNA in 7 (26.9%) of 26 patients with DCM, and none of patients with MI. And none of DNA viruses tested were detected from the samples. Amplified products were also genotyped by single-variation of EV is present in the explanted heart tissues from patients with DCM. Although most of the sequences among the wild isolates have the greatest similarity to those of coxsackievirus B3, there are specific regions of variable sequences (no 490 - no 510). The data suggest that enterovirus may be a major viral pathogen for the DCM in Korea and nucleotide sequence data indicate that coxsackievirus B3 may be a leading etiologic agent of DCM.

Etiology and Clinical Features of Severe Acute Viral Lower Respiratory Tract Infections in Children

PURPOSE: The purpose of the study is to understand the etiology and clinical features of severe acute viral lower respiratory tract infection(LRI), especially in conjunction with the use of ventilator care and/or with bronchiolitis obliterans. METHODS: Etiologic agents and clinical features of severe acute viral LRI were studied from July 1998 through June 1999 in children at Asan Medical Center. The viruses were identified by shell viral technique. Medical records of children with proven viral LRI were reviewed retrospectively. RESULTS: 81 cases were confirmed as respiratory viral infection. The identified pathogens were influenza virus(32.1%), parainfluenza virus(PIV, 29.9%), respiratory syncytial virus(RSV, 16.0%), adenovirus(11.0%), and mixed viruses(11.0%). Clinical patterns of viral LRI were pneumonia(46.9%), bronchiolitis(38.3%), croup(7.4%), and tracheobronchitis(7.4%). 29.6 percents of patients had a fever of 38.5C degree or higher and their most common etiologic agent was influenza virus(33.3%). 30.8 percents of patients had fever for 5 days or more and their most common etiologic agent was RSV(31.3%). 35.8 percents of patients showed cyanosis and their most common etiologic agent was PIV(31.0%). CRP (more than 4.0mg/dL) was increased in 33.8%, and their common etiologic agents were RSV and PIV(29.9%). Abnormal liver function test was detected in 19.4%, and the most common etiologic agent was RSV(50.0%). 5 patients(6.2%) showed clinical and radiologic findings consistent with bronchiolitis obliterans and their most common etiologic agent was influenza virus(60.0%). CONCLUSION: Influenza virus, PIV, and RSV were common etiologic agents in severe viral respiratory tract infection in children.

Augmented Surgery for Partially Accommodative Esotropia

The conventional surgery, based on the nonaccommodative angle after full correction of a hypermetropic refractive error, has resulted in a high incidence of undercorrection in the partially accommodative esotropia. In this study, we compared the conventional surgery group (82 patients)to the augmented surgery group (102 patients)in a total of 184 patients.The follow-up period in each group was at least 6 months. Of the 82 patients in conventional surgery group, 55 (67%)showed postoperative deviations of 10 delta or less, 25 (30%)undercorrection, and 2 (3%)overcorrection.Of the 102 patients in augmented surgery group, 81 (79%)revealed postoperative deviations of 10 delta or less, 9 (9%)undercorrection, and 12 (12%) overcorrection.The deviation was improved toward orthotropia by spectacle reduction of less than +2.0 D in overcorrected patients (2 of 2 in conventional surgery group, and 9 of 12 in augmented group).But 3 patients in augmented surgery group remained overcorrected. Our conclusion is that augmented surgery, even if it increase overcorrection, provides better postoperative alignment than conventional surgery in partially accommodative esotropia.

Detection of resistance mutation to lamivudine in HIV-1 infected patients

To investigate resistance to lamivudine (3TC), we examined the incidence of M184V in 20 HIV-1 patients treated with 3TC for 13.1 +/- 9 months. Fourteen of 20 patients had been exposed to zidovudine (ZDV) or didanosine (ddl) prior to 3TC therapy. Nested PCR targeting to reverse transcriptase (RT) and direct sequencing were performed for peripheral blood mononuclear cells sampled serially. There were resistance mutations to ZDV in at least 9 patients at baseline, although there was no resistance mutation to 3TC. We could detect M184V in 6 (30%) out of 20 patients. The incidence of M184V increased as the duration of therapy prolongs (13% in samples<12 months; 47% in samples gtoreq 12 months). The frequency of mutation M184V was higher in patients with previous mutation to ZDV than in patients with wild type. Resistance mutation was not detected in 7 patients. This study shows that resistance to 3TC tends to develop rapidly in patients with baseline mutations or two drugs combination therapy than in those treated simultaneously with triple drugs. This report is the first on resistance to 3TC in Korean AIDS patients.

Epidemiological Analysis of Viral Respiratory Infections and Comparison of Isolation Rate of Various Clinical Specimens / 감염

BACKGROUND: We studied the epidemics of respiratory viral infections in Korea and examined various respiratory tract specimens for the presence of respiratory viruses, since the accuracy of rapid detection method depends, in part, on the source of the specimens. METHODS: Over a 24-month period, from March 1997 through February 1999, a total of 1,574 clinical specimens were submitted for the detection of respiratory viruses. A shell vial technique with commercially available monoclonal antibodies directed against respiratory viruses was used to detect respiratory syncytial virus, adenovirus, influenza virus, and parainfluenza virus in clinical specimens, which included throat swab, nasopharyngeal aspirate, tracheal aspirate, and bronchoalveolar lavage (BAL) fluid. RESULTS: Overall positive rate of respiratory viruses was 73/1574 (4.6%). Respiratory viruses were predominantly found between December and February. High incidences were observed among those younger than 2 years and those older than 50 years. The numbers of viral isolates were 3/69 (4.3%) for throat swab, 26/459 (5.7%) for nasopharyngeal aspirate, 11/315 (3.2%) for tracheal aspirate, and 30/528 (5.7%) for BAL fluid. CONCLUSIONS: Nasopharyngeal aspirate and BAL fluid appear to permit increased detection of the respiratory viruses compared with throat swab or tracheal aspirate. However, throat swab may be good specimen for the detection of influenza virus and parainfluenza virus.

Detection of Mutations to Zidovudine in the pol Gene of Human Immunodeficiency Virus-1 by Direct Sequencing

No abstract available.

4 Cases of Pseudomonas Scleritis after Pterygium Excision

It is known that the treatment of pseudomonas aeruginosa infection associated with scleral necrosis after pterygium excision is difficult. Pseudomonas scleritis were treated with systemic and topical antibiotics, debridement, scleral homograft,and conjunctival autograft in 3 cases of 4 cases. Another 1 case was transfered to other hospital with patient`s request after short medical treatment. The interval from pterygium operation to onset of pseudomonas scleritis ranged from 2 to 17 years with an average of 10 years. In all cases with operation, the graft was stabilized after mean time of 42 days (ranged 35 to 48 days) from operation. The complications were visual disturbance, endophthalmitis, complicated cataract, exudative retinal detachment, exotropia, and posterior synechia of iris. In 1 case, a corticosteroid which was used in the early of treatment induced exacerbation of disease.Because the complications of disease were so severe,early prophylactic operation will be necessary in noninfected scleral necrosis, and when infection is suspected, it should be necessary to do culture and sensitivity test with an intensive anti-pseudomonal therapy.

CMV Infection in AIDS Patients Depends on the Decrease of CD4+ T Cell Count eauth

Cytomegalovirus is the most common cause of life-threatening viral infection in HIV-infected patients. This study was done prospectively to investigate the incidence of CMV infection according to the decrease of CD4+ T cell count (CD4+) in Korean AIDS patients. Thirty-nine HIV-infected patients diagnosed before 1994 were followed for regular immunological monitoring. We have used urine shell vial method for the CMV detection from 1994 and have also checked clinical findings. Positive urine culture rate definitely depended on the CD4+ as follows; 45%, 22%, 17%, 11% and 0%, CD4+ >50, 50-100, 100-200, 200-500 and <500, respectively. Except culture positive 2 patients with CD4+ of 200~300/ul, all eight culture positive patients with CD4+ less than 200/ul showed CMV related diseases on or before urine culture. But, we could not get a positive culture for a late AIDS patient with vision loss. With ganciclovir therapy, all culture results were at least negative just after or on late of first 14 days-ganciclovir infusion-course. These data suggest that the incidence of CMV disease in Korean AIDS patients is very high, and early diagnosis and treatment for CMV diseases is required for the prevention of life threatening results.

Sequence Analysis of C2-V3 Region of Human Immunodeficiency Virus Type 1 gp120 and its Correlation with Clinical Significance : the Effect of Long-Term Intake of Korean Red Ginseng on env Gene Variation

Human immunodeficiency virus type 1 (HIV-1) phenotype plays an important role in the pathogenesis of AIDS. The presence of syncytium-inducing (SI) HIV-1 isolates in infected persons is associated with a rapid decline of CD4+T cells (CD4+), rapid disease progression, and reduced survival time after AIDS diagnosis. We have reported the effects of Korean red ginseng (KRG) on HIV-1 infected patients. To investigate whether KRG affects HIV-1 at gene level and there is a correlation between genotype and decline of CD4+, the C2-V3 region of env gene from 65 HIV-1 isolates were cloned and sequenced. Distributions of subtype were subtype B 57 (88%), subtype A 4 (6%), subtype C 2 (3%), subtype G 1 (2%), and subtype H 1 (2%). The prevalences of SI according to the number of CD4+ are as follows; 40% (6/15) in CD4+ 200/ul. Seventy-five percent (6/8) of SI were detected in rapid progressor with the decline of CD4+ over 60/ul per year. The correlation between SI genotype and the detection of immune complex dissociated (ICD) p24 antigen was significant (p<0.001). In the 40 patients followed-up over 60 months by CD4+, there was significant correlation between annual decrease of CD4+ and duration of KRG intake (R=-0.380, p<0.01), whereas no correlation between CD4+ and zidovudine (ZDV) was observed. The intrapatient variation of amino acid level showed significant inverse correlation with the months of KRG intake (R=-0.47, p<0.01). These results suggest that the determination of genotype by C2- V3 sequencing may be used for the evaluation of prognosis of AIDS patient, and long-term intake of KRG may prevent or delay the progression from NSI to SI.

The Development of Molecular Detection Method and Differentiation of Genotypes of Enterovirus

In this study, the feasibility of identification and genotypic differentiation of enteroviruses was investigated by using nested reverse transcription-polymerase chain reaction (nested RT-PCR), single-stranded conformation polymorphism (SSCP), and restriction fragment length polymorphism (RFLP) techniques. Two hundred seventy-four clinical samples were assayed by both nested RT-PCR and tube culture method using MRC-5 and MK cells; 58 (86.6%) out of 67 enterovirus culture-positive samples contained enteroviral RNA. In addition, 114 (55.1%) of 207 samples from patients with suspected enteroviral CNS disease with negative viral cultures were positive by the nested RT-PCR. The nested RT-PCR products were genotyped by the SSCP method and the results were compared with serotypes. We could differentiate 6 subtypes, 3 of which are similar to coxsackievirus B3, B5, echovirus 11, plus 3 other subtypes. RFLP cleaved with Sty I, Bgl I, and Xmn I yielded characteristic patterns for each laboratory strains. This study demonstrates the usefulness of the RT-PCR for the rapid diagnosis of enterovirus infection and the potentials of the SSCP method for differentiation of enterovirus strains.

Innovative curriculum of Ulsan Medical College: Introduction, experience and prospect / 한국의학교육

No abstract available.

Experience of New Curriculum in college of Medicine, University of Ulsan / 한국의학교육

It has pointed out that there are problems in the traditional medical education in Korea. First of all, basic science and clinical education were not integrated so that students can not develop abilit ies to incorporate scientific concepts and principles into solving clinical problems. In order to improve medical education, new educational program was developed in College of Medicine, University of Ulsan, which started medical education in 1990. Among the many types of new medical educational system, the program from the University of Calgary, which was thought to be more applicable to educational environment in Korea, was adopted. The new program comprises principles of (1) integrated teaching, (2) patient-oriented, (3) problem-oriented, (4) student-oriented, (5) adoption of core and elective course and (6) self learning. During the first two year period, integrated curriculum of eleven system courses(musculoskeletal, hematology oncology, immunology and infection, gastroenterology, endocrinology, reproductive, nephrology, cardiology, pulmonology and neuroscience), introductory course, continuity course, elective course, clinical skills, independent study and integrative course were proceeded. Students have spent the last two years in clinical clerkships, including 4 months of elective course. Students evaluated the integrated curriculum as being satisfactory for clinical education, but not enough for basic science education.

Early diagnosis of pneumocystis carinii pneumonia by calcofluor white stain in bronchoalveolar lavage fluid / 감염

No abstract available.