Development of Measles Immunoglobulin M Detecting Enzyme-Linked Immunosorbent Assay (IgM ELISA) Using Recombinant Nucleoprotein of Measles Virus

Rapid and reliable diagnosis of measles is important to establish an appropriate therapy and to monitor the epidemic. However, classical ELISA methods using purified virus or virus-infected cells as antigens are not only difficult to determine optimal condition for diagnosis but also highly expensive to establish routine and appropriate diagnostic systems. Nucleoprotein of measles virus is one of the major antigens of measles virus that evoke initial IgM responses. It can be used as an attractive antigen for sero-diagnosis of measles during early infection. To develop simple and inexpensive diagnostic method for measles, we expressed a recombinant nucleoprotein (60-kDa) and a fragmented portion of the nucleoprotein (50-kDa) in E. coli and evaluated their appropriateness as diagnostic antigens. The proteins strongly reacted with sera from measles patients but not with normal control sera. Efficiency of recombinant nucleoprotein-ELISA (rN-ELISA) to detect IgM was compared that of whole measles virus-ELISA (MV-ELISA) on the basis of a clinical diagnosis. In rN-ELISA, sensitivity was 73.8% and agreement was above 76.4%. In MV-ELISA, sensitivity was 76.9% and agreement was 79.2%. Therefore, efficacy of rN-ELISA seemed to be similar to that of MV-ELISA. In addition, we compared with Edmonston rN-ELISA and Korean isolate rN-ELISA on the basis of commercial MV-ELISA. In Edmonston rN-ELISA, sensitivity was 94.0% and agreement was 98.4%. In the case of Korean isolate rN-ELISA, sensitivity was 96.0% and agreement was 96.9%. Thus, there was no significant difference in the efficacy between Edmonston rN-ELISA and Korean isolate rN-ELISA. Furthermore, the correlation coefficient (R2) between Edmonston rN-ELISA and Korean isolate rN-ELISA was 0.9925. These results suggest both Edmonston and Korean isolate rN-ELISA may be useful to diagnose measles.

Genetic Characterization of Haemagglutinin 1 Domain of Influenza B Viruses Isolated in Korea during 1988~1999

Although Korean influenza virus isolates have been genetically associated with the vaccine strains of the corresponding year, influenza B viruses have prevailed almost every year in Korea during the past decades. We have analyzed the genetic characteristics and evolutionary patterns of the haemagglutinin (HA) 1 domains of influenza B viruses isolated during 1988-1999 using direct RT-PCR and sequencing. Phylogenetic analysis of influenza B viruses isolated in Korea indicated that antigenically and genetically distinguishable strains of the lineage II and lineage III variants had been cocirculated. Variants prevailed in early 1990s are represented in 1996/97 and 1998/99 and some different variants have been cocirculated geographically and prevailed concurrently in Korea. All HA1s of Korean isolates have amino acid substitutions mainly in the region between position 124 and 310, which was previously proposed an immunodominant region. Insertion-deletion patterns of the HA gene revealed that Korean influenza B viruses were evolved from Lee40 with different manner between lineage II and III viruses. Lineage III viruses were also divided into two groups as conserved group and inserted group, in relation to Lee40. But lineage II viruses had evolved with directional pattern. Antigenic index proposed that influenza B isolates prevailed since 1996/97 seasons might had emerged from the antigenic variants of a Seo1697-like virus and that new variants might appear from the lineage II viruses resulting in persistent prevalence in Korea.

Clinico-epidemiologic and Virologic Study of Measles Outbreak in Gwangju Metropolitan City During the 2000~2001 Epidemic / 감염

BACKGROUND: Measles is a highly contagious disease caused by measles virus. Although the introduction of live attenuated measles vaccines has dramatically abrogated the endemic incidence of measles in world-wide, there are still 30 million measles cases and nearly one million deaths from measles annually. In this study, we characterized the measles outbreak in Gwangju Metropolitan City during the 2000~200 1 epidemic. METHODS: Study population included measles patients in Gwangju Metropolitan City from April, 2000 to May, 200 1. We conducted a questionnaire survey on the patients and analyzed the records based on the clinical guideline of World Health Organization (WHO). Furthermore, we isolated the measles viruses from clinical specimens of patients and analyzed the nucleotide sequences of nucleoprotein (N) gene. RESULTS: During the April 2000 to May 2001, measles epidemic, a total of 3,2 17 measles patients were reported in Gwangju Metropolitan City. The first patient of measles was reported on April, 2000. The incidence reached its peak in November, 2000 and decreased thereafter. The age distribution of the patients were various, which was ranged from 1 month after birth to 30 year adult and the peak incidence was observed at 7~13 year old. Various complications were developed in 232 patients and 2 of them died. Phylogenetic analyses of nucleotide sequences and deduced amino acid sequences of the N genes of isolated viruses revealed that all viruses isolated in Gwangju Metropolitan City were grouped into the clade H1. This suggests that a single, predominant viral genotype was responsible for the measles epidemic in Gwangju Metropolitan City. CONCLUSION: In this study, we characterized the measles outbreak in Gwangju Metropolitan City during 2000~200 1. The measles outbreak in Gwangju Metropolitan City was considered to be caused by single genotype of measles virus (clade H1). After a massive vaccination campaign among 7~16 years old children to eliminate indigenous measles from this country, it is important to continue measles vaccination and intensive surveillance clinically as well as virologically.

Seroepidemiology of Mumps IgG Antibody on Primary School Children in Kyonggi Province, 1996 and 1999 / 감염

BACKGROUND: Although massive use of live attenuated mumps virus vaccines successfully reduced the incidence of mumps virus infection worldwide, mumps outbreaks have not been completely eliminated, even in vaccinated populations. In recent years, the incidence of mumps has been remarkably increased in Korea. This study was designed to evaluate the recent seroprevalence rate of mumps IgG among children in Kyonggi province at 1996 and 1999. METHODS: Study population included students from 8 elementary schools in Kyonggi province. Serum samples were collected twice at 1996 and 1999 and tested for mumps-specific antibody by enzyme-linked immunosorbent assay (ELISA). We also conducted a questionnaire survey on the parents and collected the records including history of vaccination and mumps infection. RESULTS: The seropositive rates against mumps were 89.47% and 89.74% at 1996 and 1999, respectively, and they were not significantly different when compared to age, sex, and region. Although the first vaccination rates were 92.17% and 92.25% at 1996 and 1999, respectively, the second vaccination rates were only 37.89% and 38.03% at 1996 and 1999, respectively. Infection rate showed no significant difference between vaccinated groups and nonvaccinated groups. Seropositive rate of infected group was higher than that of noninfected group but it was not significantly different between the vaccinated and the nonvaccinated. CONCLUSIONS: This study showed the seropositive rate and vaccination against mumps in children. There were no significant relationships between vaccination and infection. Therefore, it seems likely that the vaccination is not fully protective against mumps infection. This study will be helpful for the establishment of guideline for prevention and treatment of mumps in Korea.

Development of Multiplex Reverse Transcription Polymerase Chain Reaction for Detection and Typing of Parainfluenza Viruses

No abstract available.

Viral Etiology of Community-acquired Pneumonia in Korean Adults / 감염

PURPOSES: To investigate the viral etiology of community-acquired pneumonia in Korean adults, we have detected respiratory viruses (Respiatory syncytial virus, adenovirus, influenza virus and parainfluenza virus) in the way of prospective, multi-center study. METHODS: From July 1997 to April 2000, nasal aspirates or sputum were obtained from adults patients with community pneumonia admitted to the participating hospitals and transferred immediately to the central laboratory in the Seoul National University Children's Hospital. The specimens were divided into three parts. One part was used for indirect immunofluorescent test for respiratory viruses, the other part for the culture of RSV and adenovirus in HEp-2 cell monolayer. Another part was used for the culture of influenza virus and parainfluenza virus in MDCK or LLC- MK2 cell monolayers. RESULTS: Of 317 samples, 32 (10.1%) specimens were positive for viral isolation by indirect IF staining or culture, including one dual-infected specimen (adenovirus and parainfluenza virus). Influenza virus was most commonly detected (16 specimens). Parainfluenza virus, adenovirus and RSV were detected in 10, 4 and 3 patients, respectively. All isolated influenza viruses were type A (H3N2 in 9 patients, H1N1 in 2 and unspecified in 5), and 8 out of 10 parainfluenza virus isolates were type 3. CONCLUSION: Similar to previous foreign reports, a significant portion of community-acquired pneumonia in Korean adult is caused by respiratory viruses. Our data empathized the need of referral system for viral diagnosis and of nationwide investigation on respiratory virus infections.

National Surveillance in Influenza Outbreak during Winter of 1997 and 1998 in Korea / 감염

BACKGROUND: Influenza is a pandemic disease because of the frequent antigenic variation. There is an international influenza network by WHO, but no national surveillance system has been established in Korea. The purpose of this study was to understand the influenza epidemiology by examining the incidence of influenza-like illness (ILI) and the subtype of isolated viruses in Korea during the winter of 1997 and 1998. METHODS: The consultation rates and clinical features of ILI were based on the weekly reports by 71 sentinel physicians (SP) from October 1997 to March 1998. Throat swabs from patients with ILI were collected and inoculated to Madin-Darby Canine Kidney (MDCK) cells. Isolates were identified by hemagglutination (HA), indirect immunofluorescence assay (IFA) and confirmed by hemagglutination inhibition (HI), and restriction fragment length polymorphism (RFLP). RESULTS: The incidence of ILI and virus isolation peaked in December 1997 and decreased to the baseline in February 1998. Influenza occurred mostly in 1- to 5-years old children and systemic symptoms were the main clinical features. One-hundred and thirty two influenza viruses among 2,071 specimens were isolated. The major subtype of isolates was A/H3N2 (A/Sydney/05/97). A/H1N1 subtype was isolated at low levels (4 strains), whereas B and A/ H5N1 were not. RFLP for M gene was compatible with those bands of A/H3N2 and A/H1N1. CONCLUSION: Influenza epidemiology was studied on the basis of a nationwide surveillance system during 1997 and 1998. The incidence of ILI and virus isolation peaked in December 1997 and predominant strains of isolates were closely related to A/H3N2. To establish a more effective system, it is necessary to increase the number of participating SP and laboratories.