Sunyoung Jung

Omsk hemorrhagic fever is an acute zoonotic disease caused by Omsk hemorrhagic fever virus, a member of the genus Flavivirus (family Flaviviridae), with a reported case-fatality rate of approximately 3%. Historically confined to southwestern Siberia, ecological changes raise concerns about possible spread to non-endemic regions. Although no Omsk hemorrhagic fever cases have been reported in the Republic of Korea, the risk of accidental importation highlights the importance of establishing a reliable diagnostic protocol. We established and validated an institutionally developed diagnostic protocol employing real-time reverse transcription polymerase chain reaction targeting the NS2A and C genes of Omsk hemorrhagic fever virus. Primers and probes were designed from all available genomes to ensure broad strain coverage. Human ribonuclease P was used as an internal control to verify nucleic acid extraction and amplification. Using synthetic deoxyribonucleic acid fragments and in vitro-transcribed ribonucleic acid, assay performance was optimized, and analytical sensitivity was determined using probit analysis. The limits of detection were 74.50 copies/µL (threshold cycle 32.99) for NS2A and 70.41 copies/µL (threshold cycle 35.38) for C. Specificity testing using representative flaviviruses (West Nile virus, Yellow fever virus, Zika virus, St. Louis encephalitis virus, and Tick-borne encephalitis virus) and an alphavirus (Venezuelan equine encephalitis virus) demonstrated no cross-reactivity. The assay demonstrated high sensitivity, specificity, and reproducibility, supporting its potential application in national and international Omsk hemorrhagic fever virus surveillance systems.

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An epidemiological survey on human norovirus (NoV)–associated gastroenteritis was conducted to clarify the prevalence of NoV infections in children and adults in Korea. Recombinant capsid proteins from three major NoV genotypes (GI-4, GII-3, and GII-4) were expressed using a baculovirus expression system, and the morphology and antigenicity of self-assembled virus-like particles were then confirmed by electron microscopy and Western blotting with a NoV-specific antibody. To determine seroprevalence, an enzyme-linked immunosorbent assay was performed to detect antibodies against virus-like particles antigen in 346 serum specimens collected from persons who visited five public heath care centers for regular physical examination in Jeollanam-do, Korea, between 2005 and 2006. The seroprevalence of immunoglobulin G antibodies against the GI-4, GII-3, and GII-4 NoV genotypes was 84.1%, 76.3%, and 94.5%, respectively. A rapid decrease in seroprevalence occurred after birth, with the lowest levels observed in the p<0.01).