• Pediatric Infection and Vaccine
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• v.13 no.1
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• pp.63-70
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• 2006

Purpose : We hypothesized that mannose binding lectin gene(MBL2), a key molecule of innate immunity, may contirbute to the development and the outcome of respiratory syncytial virus(RSV) disease in early childhood. This study was performed to investigate the genetic basis of polymorphisms and haplotypes of MBL2 for RSV disease severity in Korean children. Methods : Cases with severe RSV diseases are 99 children with severe RSV lower respiratory tract infections, who were admitted to the Seoul National University Children's Hospital through 1993~2000. The control subjects consisted of 224 anonymous healthy Korean blood donors. The frequency of promoter variant(-221, X/Y) and structural variant(codon 54) were compared between the case patient group and the control subject group. Results : The mean age of patients was 11.8 months; 49% were <6 months, 39% were 6-24 months and 12% were >24 months. In the cohort of cases of severe RSV diseases, the genotypic frequencies of structural variant in codon 54 were 61% for AA, 34% for AB, and 5% for BB. Those of the promoter X/Y variant were 85% for YY and 15% for XY. There were no significant differences in overall distribution of both structural and promoter variants between the cases and the control subjects. We did not observe statistical difference in the haplotypic frequencies of MBL2. Conclusion : Common variants of MBL2 gene most likely do not contribute to the risk for severe RSV diseases in Korean children. Further genetic association studies should be conducted in a larger propsectively recruited cohort of children with RSV infection.

• Journal of Microbiology
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• v.45 no.1
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• pp.21-28
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• 2007

In order to search for specific genotypes related to this unique phenotype, we used whole genomic DNA microarray to characterize the genomic diversity of Helicobacter pylori (H. pylori) strains isolated from clinical patients in China. The open reading frame (ORF) fragments on our microarray were generated by PCR using gene-specific primers. Genomic DNA of H. pylori 26695 and J99 were used as templates. Thirty-four H. pylori isolates were obtained from patients in Shanghai. Results were judged based on In(x) transformed and normalized Cy3/Cy5 ratios. Our microarray included 1882 DNA fragments corresponding to 1636 ORFs of both sequenced H. pylori strains. Cluster analysis, revealed two diverse regions in the H. pylori genome that were not present in other isolates. Among the 1636 genes, 1091 (66.7%) were common to all H. pylori strains, representing the functional core of the genome. Most of the genes found in the H. pylori functional core were responsible for metabolism, cellular processes, transcription and biosynthesis of amino acids, functions that are essential to H. pylori's growth and colonization in its host. In contrast, 522 (31.9%) genes were strain-specific genes that were missing from at least one strain of H. pylori. Strain-specific genes primarily included restriction modification system components, transposase genes, hypothetical proteins and outer membrane proteins. These strain-specific genes may aid the bacteria under specific circumstances during their long-term infection in genetically diverse hosts. Our results suggest 34 H. pylori clinical strains have extensive genomic diversity. Core genes and strain-specific genes both play essential roles in H. pylori propagation and pathogenesis. Our microarray experiment may help select relatively significant genes for further research on the pathogenicity of H. pylori and development of a vaccine for H. pylori.

• Korean Journal of Microbiology
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• v.53 no.1
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• pp.1-8
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• 2017

Measles virus is a highly contagious, exanthematic virus, preventable by the use of an effective live-attenuated vaccine. However, measles virus remains endemic in many area of the world causing nearly 200,000 deaths per year and still a major cause of child mortality, mostly in developing countries. In March 2014, Republic of Korea was certified as a 'national measles elimination' by the WHO as a result of a high-quality case-based surveillance system and population immunity, which was achieved by a high vaccination rate (>95.0% since 1996). But, since the beginning of 2014, the Gyeonggi province has experienced a resurgence of measles cases. In this study, we investigated the characteristics of measles viruses isolated from confirmed measles in Gyeonggi province during January 1, 2014 ~ July 31, 2014, 60 isolates were obtained from 72 confirmed measles specimens. Genotypic distributions and genetic diversities of isolated measles virus were analyzed by sequencing of nucleoprotein (N) gene. 58 (96.7%) imported cases were identified. The predominant genotype was B3, which reflects the circulating measles virus in adjacent countries. The sequences of nucleoprotein (N) gene of isolated MeV were showed that the strains characterized showed the highest degree of identity (99%) with the Philippine related strains in 2013-2014. Therefore, infected traveler returning from the Philippines transmitted secondary infection in Korea.

• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.363-370
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• 2014

Campylobacter jejuni is a prevalent foodborne pathogen worldwide. Human infection by C. jejuni primarily arises from contaminated poultry meats. Genes expressed in vivo may play an important role in the pathogenicity of C. jejuni. We applied an immunoscreening method, in vivo-induced antigen technology (IVIAT), to identify in vivo-induced genes during human infection by C. jejuni. An inducible expression library of genomic proteins was constructed from sequenced C. jejuni NCTC 11168 and was then screened using adsorbed, pooled human sera obtained from clinical patients. We successfully identified 24 unique genes expressed in vivo. These genes were implicated in metabolism, molecular biosynthesis, genetic information processing, transport, and other processes. We selected six genes with different functions to compare their expression levels in vivo and in vitro using real-time RT-PCR. The results showed that the selected six genes were significantly upregulated in vivo but not in vitro. In short, these identified in vivo-induced genes may contribute to human infection of C. jejuni, some of which may be meaningful vaccine candidate antigens or diagnosis serologic markers for campylobacteriosis. IVIAT may present a significant and efficient method for understanding the pathogenicity mechanism of Campylobacter and for finding targets for its prevention and control.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.83-89
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• 2022

Since the pandemic of COVID-19, active investigation to develop immunity to infectious disease by delivering nucleic acids has been proceeded. Particularly, many studies have been conducted on non-viral vector as several vital side-effects which were found on nucleic acid delivery system using viral vectors. In this study, we have developed plasmid DNA (pDNA) loaded-hyaluronic acid derivative (HA) coated-polyethyleneimine (PEI) based polyplex for enhanced nucleic acid delivery efficiency. We have optimized the ratio of pDNA : PEI : HA by measuring size and protein transcription efficiency. The final product, polyplex-HA, was characterized through measuring size, zeta-potential and TEM image. Intracellular uptake and protein transcription efficiency were compared to commercially available transfection reagent, lipofectamine, through fluorescence image and flow cytometry. In conclusion, polyplex-HA presents a novel gene delivery system for efficient and stable protein transcription since it is available for delivering various genetic materials and has less immunoreactivity.

• Journal of Life Science
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• v.32 no.2
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• pp.94-100
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• 2022

Chronic infection by hepatitis B virus (HBV) greatly increases the risk for liver cirrhosis and hepatocellular carcinoma (HCC). The outcome of HBV infection is shaped by the complex interplay of the mode of transmission, host genetic factors, viral genotype, adaptive mutations, and environmental factors. The pregenomic RNA transcription of HBV for their replication is regulated by the core promoter activation. Core promoter mutations have been the reason for acute liver failure and are associated with HCC development. We obtained HBV genes from a patient in Myanmar who was infected with HBV and identified gene variations in the core promoter region. For measuring the relative transactivation activity of the core promoter, we prepared the core-promoter reporter construct. Among the gene variations of the core promoter, the mutations of C1731T and G1806A were associated with increase in the transactivation of the HBV core promoter. Through computer analysis for searching for a tentative transcription factor binding site, we showed that the mutations of C1713T and G1806A newly created C/EBPβ and XBP1-responsive elements of the core promoter, respectively. The ectopic expression of C/EBPβ largely increased the HBV core promoter containing the C1713T mutation and that of XBP1 activated the M95 promoter containing the G1806A mutation. Our efforts to treat and prevent HBV infections are hampered by the emergence of drug-resistant mutations and vaccine-escape mutations. Our results provide the biological properties and clinical significance of specific HBV core promoter mutations.

• Journal of Life Science
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• v.33 no.8
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• pp.605-611
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• 2023

Recently, sporadic cases of human infection by genetic reassortants of H7Nx influenza A viruses have been reported; such viruses have also been continuously isolated from avian species. In this study, A/wild bird/South Korea/sw-anu/2023, a novel reassortant of the H7N1 avian influenza virus, was analyzed using full-genome sequencing and molecular characterization. Phylogenetic analysis showed that A/wild bird/South Korea/sw-anu/2023 belonged to the Eurasian lineage of H7Nx viruses. The polymerase basic (PB)2, PB1, polymerase acidic (PA), and nucleoprotein (NP) genes of these viruses were found to be closely related to those of avian influenza viruses isolated from wild birds, while the hemagglutinin (HA), neuraminidase (NA), matrix (M), and nonstructural (NS) genes were similar to those of avian influenza viruses isolated from domestic ducks. In addition, A/wild bird/South Korea/sw-anu/2023 also had a high binding preference for avian-specific glycans in the solid-phase direct binding assay. These results suggest the presence of a new generation of H7N1 avian influenza viruses in wild birds and highlight the reassortment of avian influenza viruses found along the East Asian-Australasian flyway. Overall, H7Nx viruses circulate worldwide, and mutated H7N1 avian viruses may infect humans, which emphasizes the requirement for continued surveillance of the H7N1 avian influenza virus in wild birds and poultry.

• Pediatric Infection and Vaccine
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• v.12 no.2
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• pp.166-177
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• 2005

Purpose : The purpose of this study was to examine the molecular epidemiology and genetic variability of adenovirus(Ad) serotypes Ad1, Ad2, and Ad5 over 14 years in Korea. Methods : A total of 382 adenoviral strains isolated from the nasopharyngeal aspirates of children with lower respiratory tract infections in Seoul, Korea from November 1990 to February 2003 were serotyped by neutralization assay with type-specific antisera. Viral DNAs were extracted from infected cell lysates by the modified Hirt procedure. Genome type(GT) was determined by DNA restriction analysis with 12 restriction enzymess(BamHI, BclI, BglI, BglII, BstEII, EcoRI, HindIII, HpaI, SalI, SmaI, XbaI, and XhoI). To evaluate the genetic relatedness, pairwise comigrating restriction fragments(PCRF) analysis was performed. Results : Of 382 strains, 33 strains(9%) were Ad1, 45 strains(12%) were Ad2, and 24 strains(6%) were Ad5. Eighteen GTs(Ad1p1-Ad1p7, Ad1a, Ad1b, Ad1b1-Ad1b3, Ad1c, Ad1d, Ad1e, Ad1e1, Ad1e2, Ad1f) among Ad1, 24(Ad2p1-Ad2p11, Ad2a, Ad2a1-Ad2a6, Ad2b, Ad2c, Ad2d, Ad2e, Ad2e1-Ad2e3) among Ad2, and 10(Ad5p1, Ad5p2, Ad5a, Ad5a1-Ad5a7) among Ad5 strains were identified. One or two strains of the vast majority of GTs were isolated during the study period while a few GTs were identified sporadically with more than 2 strains. It is notable that some GTs such as Ad1p5 and Ad5a1 appeared in cluster during a short period. In analysis of genetic relatedness, the degree of PCRFs(pairwise comigrating restriction fragments) for Ad1 varied from 79 to 99%, for Ad2, 82 to 99%, and for Ad5, 85 to 99%. Conclusion : This study established the comprehensive nomenclature systems of Ad1, Ad2, and Ad5. Diverse GTs identified in this study have crucial implications in the genomic diversity and epidemiological characteristics of Ad1, Ad2, and Ad5.

• Pediatric Infection and Vaccine
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• v.23 no.1
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• pp.46-53
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• 2016

Purpose: Enterovirus (EV) infection in children can manifest various diseases from asymptomatic infection to nonspecific febrile illness, hand-foot-mouth disease, and aseptic meningitis. This study was aimed to investigate epidemiology and clinical significance of various genotypes of EV infections in pediatric inpatient. Methods: We collected the stool samples from the admitted pediatric patients in Inha University Hospital from March 2014 to March 2015. EV detection and genotype identification were performed by real-time RT-PCR and semi-nested RT-PCR. Phylogenetic trees were constructed by neighbor joining method. Results: A total of 400 samples were collected during study period and 112 patients (28%) were diagnosed with EV infections. The mean age of EV positive patients was 2.66 years (0.1-14) and sex ratio was 1.73:1. Genetic sequences of EVs were identified; coxsackievirus B5 (17, 15.2%), coxsackievirus A16 (13, 11.6%), enterovirus 71 (10, 8.9%), and coxsackievirus A2 (9, 8.0%). Nonspecific febrile illness (96, 86%) was the most common clinical manifestation and the duration of fever was 0-11 days (mean 3.1 days). Rash (44, 39%) and meningitis (43, 38%) were followed. Patients who were attending daycare center or had siblings accounted for 82.1%. Phylogenetic relationship tree revealed 6 distinct genogroups among 56 types of EVs. Conclusions: This study is the report of epidemiology, serotype distribution and clinical manifestations of children with EV infection in Incheon. This data will be helpful for further study about the epidemiology of EV infection in Korea.