Seroepidemiological Characteristics of Haemorrhagic Fever with Renal Syndrome from 1996 to 2005 in Korea

Haemorrhagic fever with renal syndrome (HFRS) caused by Hantaan viruses has been one of the principal acute febrile disease in Korea. To analysis the sero-epidemiological patterns of HFRS, 4,177 patient sera of acute febrile illness submitted for serological assay to National Institute of Health from Community Health Centers, Institutes of Health and Environment and hospitals from 1996 to 2005 were examined for antibodies against Hantaan virus by indirect immunofluorescent assay (IFA). Serum samples with greater than 1:32 antibody titer were considered positive. The results were analyzed seroepidemiologically by annual, sexual, seasonal, age and regional distribution of HFRS patients. Out of 4,177 serum samples tested, 1,415 samples (33.9%) were positive to Hantaan virus. The ratio of males (48.2%, 682/1,415) to females (38.2%, 541/1,415) was 1.3:1. Seasonal incidence showed that 69.5% (985/1,415) of cases occurred from October to December, resulting with higher prevalence in November (41.3%, 584/1,415). Regionally, seropositive rates of samples collected in Gyenggi, Gangwon and Chungbuk were 39.9% (564/1,415), 19.3% (274/1,415) and 8.5% (120/1,1415), respectively. Age distributions of seropositive of HFRS were detected from 20 to 79 years (78%).

Survey on the Epidemiological Characteristics of Measles Incidence between 1980 and 1999 Year in Korea / 감염

BACKGROUND: This study reports the incidences of measles in Koea and the epidemiologic characteristics for the incidence reported for the period 1980~1999. It provides the epidemeologic adta for measles before implementing the catch-up campaign in 2001. METHODS: We obtained information for the survey from the data for the incidence reported from health centers. Incidences per 100,000 population were calculated for the 1963~1999. And the following variables were studied: seasonal or regional distribution for the 1980~1999. RESULTS: The incidence rate of measles declined after the systemic immunization in 1990, the outbreak of measles occurred periodically and incidences per 100,000 population increased from 8.4 cases in 1990 to 17.7 in 1994. In 1990 and 1994, measles cases centered around the 5~6th month. On the other hand, in non-epidemic year measles cases were scattered around the year. The incidence rates of measles by the province were greatly defferent whenever the outbreak of measles occurred. CONCLUSION: In 1990s, the outbreak of measles occurred periodically at the interval of 4 years until 1994. The seasonal distribution may be caused by Iimitation of transmission due to the increased measles immunity in outbreak region. Our results showed that the measles outbreak did not occur in the specific province, but it occurred nationwide whenever measles outbreak occurred, even though the incidence rates of the provinces were different.

Epidemiological Characteristics of Measles Outbreakin 2000~2001, Korea / 감염

BACKGROUND: In 2000~2001 there was a nationwide outbreak of measles in the Republic of Korea. Since supplementary vaccination program was implemented in 2001, the control strategy of this measles outbreak has been stepped up from the control phase to the elimination phase. We here present the result of survey for the epidemiologic characteristics of the nationwide outbreak of measles in 2000~2001. METHODS: Using the data based on the sheet of epidemiologic investigation, incidences rates per 100,000 population and distributions of cases with vaccination history were investigated by the age. The seasonal or regional distribution were also studied with the onset days of cases. RESULTS: In 2000~2001, a measles outbreak occurred with 52,897 reported cases. The incidence rate per 100,000 population of measles was 111.9 cases and that of geopolitical unit (province) was high nationwide, 35.9~386.3 cases. The incidence rates were very high in less than 12 months and 10 years of age, 954.4 and 714.9, respectively. The 1st vaccination rate of measles/mumps/rubella (MMR) in 1~3 years old was 26.3~77.1%, and especially, that of 1 year old showed very low coverage, 26.3%. However, there was no special propensity in the 1st vaccine coverage in the age of 7~15 years, which had 87.7~91.4%. On the other hand, the 2nd MMR vaccination rate of the cases was very low, 17.7% at the age of 7~10 years. From the 21st May, 2001 a mass catch-up campaign with measles/rubella (MR) vaccine was launched, resulting in prominent reduction in the incidence of measles case. CONCLUSION: This survey showed that the measles outbreak in 2000~2001 had a high incidence nationwide from October 2000 to April 2001 and in less than 12 month and 10 years of age. Our results also showed that no routine immunization made the age group under 1 year vulnerable to measles infection. In cases of school-age group after 7 years of age, some cases with vaccination history were also infected. The characteristics of recent outbreaks indicates the need for the introduction of a specific vaccination programme at that age group. This survey was helpful to establish the effective vaccination strategy and it would be used as reference data on survey continuously for the epidemiologic characteristics of measles case for elimination of indigenous measles transmission in Republic of Korea.

The Role of Noncoding Region in Hantaan Viral S Genome for Expression of Nucleocapsid Protein

The genome of Hantaan virus, the prototype of the hantavirus genus, is composed of three segmented, single stranded negative sense RNA genome. The 5' and 3' termini of the Hantaan virus RNA genome contain noncoding regions (NCRs) that are highly conserved and complementary to form panhandle stuctures. There are some reports that these NCRs seems to control gene expression and viral replication in influenza virus and vesicular stomatitis virus. In this study, we examined whether NCRs in Hantaan virus play a role in expression of the viral nucleocapsid protein (Np) and foreign (luciferase) gene. The 5' and/or 3' NCR-deleted mutants were constructed and analysed. The Np expression of 5' NCR-deleted clone, it showed 40% reduction. To investigate the role of NCR in foreign gene expression, the clones which are replaced ORF of Hantaan viral Np gene with that of luciferase gene were constructed. The results were similar to those of the experiments using Np gene. These results suggest that 3' NCR is more important than 5' NCR in protein expression. To find out a critical region of 3' NCR in more important than 5' NCR in protein expression. To find out a critical region of 3' NCR in protein expression, several clones with a deleted part of 3' NCR were constructed and analyzed. The deletion of the conserved region in 3' NCR showed 20~30% decrease in Np expression. However there were no change in luciferase activities between clones with or without non-conserved region of 3' NCR. These results suggest that the 3' NCR of Hantaan virus S genome, especially conserved region in 3' NCR, plays and important role in the expression of Hantaan viral Np and foreign genes.

Analysis of the Three Dimensional Structure of Envelope Protein of the Japnes Encephalitis virus Isolated in Korea

Three dimensional structures of envelope protein from Korean isolates and Nakayama-NIH strain of Japanese encephalitis virus (JEV) were deduced by a computer program (HyperChem 4.0 Chemplus 1.0) based on the data of the three dimentional structure of Tick-borne encephalitis virus. In the three dimensional structure of envelope protein, neutralizing epitope and T-helper cell recognition site of C-terminal region of Korean isolates were structually similar to those of Nakayama-NIH but the N-terminal region was not. Korean JE isolates were compared with Nakayama-NIH strain by using cross-neutralization antibody test. Neutralizing activities of Korean isolates derived from guinea pigs were higher than those of Nakayama-NIH strain against Korean isolates, although the polyclonal antibody titers of Nakayama-NIH showed 1:160 to 1:640 against Korean isolates. According to the results from three dimentional structures and cross-neutralization analyses, the antigenic difference between Korean JE isolates and Nakayama-NIH strain may be dependent on structural difference of envelope protein.