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Objectives@#We analyzed the correlation between the infectivity and transmissibility of the severe acute respiratory syndrome coronavirus 2 Omicron sublineages BA.1, BA. 2, BA.4, and BA.5. @*Methods@#We assessed viral replication kinetics and infectivity at the cellular level. Nasopharyngeal and oropharyngeal specimens were obtained from patients with coronavirus disease 2019, confirmed using whole-genome sequencing to be caused by the Omicron sublineages BA.1, BA.2, BA.4, or BA.5. These specimens were used to infect Vero E6 cells, derived from monkey kidneys, for the purpose of viral isolation. Viral stocks were then passaged in Vero E6 cells at a multiplicity of infection of 0.01, and culture supernatants were harvested at 12-hour intervals for 72 hours. To evaluate viral replication kinetics, we determined the cycle threshold values of the supernatants using real-time reverse transcription polymerase chain reaction and converted these values to genome copy numbers. @*Results@#The viral load was comparable between BA.2, BA.4, and BA.5, whereas BA.1 exhibited a lower value. The peak infectious load of BA.4 was approximately 3 times lower than that of BA.2 and BA.5, while the peak load of BA.2 and BA.5 was about 7 times higher than that of BA.1. Notably, BA.1 demonstrated the lowest infectivity over the entire study period. @*Conclusion@#Our results suggest that the global BA.5 wave may have been amplified by the higher viral replication and infectivity of BA.5 compared to other Omicron sublineages. These analyses could support the rapid assessment of the impact of novel variants on case incidence.
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While the coronavirus disease 2019 pandemic is ongoing, monkeypox has been rapidly spreading in non-endemic countries since May 2022. Accurate and rapid laboratory tests are essential for identifying and controlling monkeypox. Korean Society for Laboratory Medicine and the Korea Disease Prevention and Control Agency have proposed guidelines for diagnosing monkeypox in clinical laboratories in Korea. These guidelines cover the type of tests, selection of specimens, collection of specimens, diagnostic methods, interpretation of test results, and biosafety. Molecular tests are recommended as confirmatory tests. Skin lesion specimens are recommended for testing in the symptomatic stage, and the collection of both blood and oropharyngeal swabs is recommended in the presymptomatic or prodromal stage.
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Objectives@#Coronavirus disease 2019 (COVID-19) has been declared a global pandemic owingto the rapid spread of the causative agent, severe acute respiratory syndrome coronavirus 2.Its Delta and Omicron variants are more transmissible and pathogenic than other variants.Some debates have emerged on the mechanism of variants of concern. In the COVID-19 wave that began in December 2021, the Omicron variant, first reported in South Africa, became identifiable in most cases globally. The aim of this study was to provide data to inform effective responses to the transmission of the Omicron variant. @*Methods@#The Delta variant and the spike protein D614G mutant were compared with the Omicron variant. Viral loads from 5 days after symptom onset were compared usingepidemiological data collected at the time of diagnosis. @*Results@#The Omicron variant exhibited a higher viral load than other variants, resulting in greater transmissibility within 5 days of symptom onset. @*Conclusion@#Future research should focus on vaccine efficacy against the Omicron variant and compare trends in disease severity associated with its high viral load.
Résumé
Since a novel beta-coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in December 2019, there has been a rapid global spread of the virus. Genomic surveillance was conducted on samples isolated from infected individuals to monitor the spread of genetic variants of SARS-CoV-2 in Korea. The Korea Disease Control and Prevention Agency performed whole genome sequencing of SARS-CoV-2 in Korea for 1 year (January 2020 to January 2021). A total of 2,488 SARSCoV-2 cases were sequenced (including 648 cases from abroad). Initially, the prevalent clades of SARSCoV-2 were the S and V clades, however, by March 2020, GH clade was the most dominant. Only international travelers were identified as having G or GR clades, and since the first variant 501Y.V1 was identified (from a traveler from the United Kingdom on December 22 nd , 2020), a total of 27 variants of 501Y.V1, 501Y.V2, and 484K.V2 have been classified (as of January 25 th , 2021). The results in this study indicated that quarantining of travelers entering Korea successfully prevented dissemination of the SARS-CoV-2 variants in Korea.
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The outbreak of coronavirus disease 2019 (COVID-19), which began in December 2019, is still ongoing in Korea, with >9,000 confirmed cases as of March 25, 2020. COVID-19 is a severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection, and real-time reverse transcription-PCR is currently the most reliable diagnostic method for COVID-19 around the world. Korean Society for Laboratory Medicine and the Korea Centers for Disease Prevention and Control propose guidelines for diagnosing COVID-19 in clinical laboratories in Korea. These guidelines are based on other related domestic and international guidelines, as well as expert opinions and include the selection of test subjects, selection of specimens, diagnostic methods, interpretation of test results, and biosafety.
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Objectives@#The Korea Centers for Disease Control and Prevention has published “A Guideline for Unknown Disease Outbreaks (UDO).” The aim of this report was to introduce tabletop exercises (TTX) to prepare for UDO in the future. @*Methods@#The UDO Laboratory Analyses Task Force in Korea Centers for Disease Control and Prevention in April 2018, assigned unknown diseases into 5 syndromes, designed an algorithm for diagnosis, and made a panel list for diagnosis by exclusion. Using the guidelines and laboratory analyses for UDO, TTX were introduced. @*Results@#Since September 9th , 2018, the UDO Laboratory Analyses Task Force has been preparing TTX based on a scenario of an outbreak caused by a novel coronavirus. In December 2019, through TTX, individual missions, epidemiological investigations, sample treatments, diagnosis by exclusions, and next generation sequencing analysis were discussed, and a novel coronavirus was identified as the causal pathogen. @*Conclusion@#Guideline and laboratory analyses for UDO successfully applied in TTX. Conclusions drawn from TTX could be applied effectively in the analyses for the initial response to COVID-19, an ongoing epidemic of 2019 - 2020. Therefore, TTX should continuously be conducted for the response and preparation against UDO.
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Human norovirus are major causative agent of nonbacterial acute gastroenteritis. In general, genogroup (G) II.4 is the most prominent major genotype that circulate in human population and the environment. However, a shift in genotypic trends was observed in Korea in December 2014. In this study, we investigated the trend of norovirus genotype in detail using the database of Acute Diarrhea Laboratory Surveillance (K-EnterNet) in Korea. GII.17 has since become a major contributor to outbreaks of norovirus-related infections and sporadic cases in Korea, although the reason for this shift remain unknown.
Sujets)
Humains , Diarrhée , Épidémies de maladies , Gastroentérite , Génotype , Corée , NorovirusRésumé
Salmonellosis is a common food- and water-borne disease and is also a major zoonosis. Currently, the isolation of rare Salmonella serotypes is increasing every year in Korea. Among them, the Salmonella serotype Tilene was first isolated from two people who visited a hospital located in Andong-si in 2013. Clinical symptoms were weak or non-existent. There was no clear epidemiological connection between the two cases. However, it was assumed that both were independently exposed to a single infectious agent. Perhaps due to their geographical proximity, molecular epidemiological analysis showed the same result between the isolated strains. This serotype has increasingly reported an association with hedgehogs. Recently, the importation of exotic animals, including hedgehogs, as pets has been gradually increasing. Thus, it is recommended that high-risk groups avoid contact with exotic pets.
Sujets)
Animaux , Hérissons , Corée , Salmonelloses , SalmonellaRésumé
Shigella is a common cause of bacterial enteritis worldwide. Shigella sonnei accounts for 90% of Shigella infections and Shigella flexneri is rarely reported in Korea. Although the incidence of Shigella infection has decreased, the incidence of organisms with antibiotic resistance has gradually increased in Korea. An outbreak of extended-spectrum β-lactamase (ESBL)-producing S. sonnei in children was reported in Korea; however, ESBL-producing S. flexneri has not yet been reported. We report the first two cases of multidrug-resistant CTX-M-14-producing S. flexneri infections in Korean children.
Sujets)
Enfant , Humains , bêta-Lactamases , Résistance microbienne aux médicaments , Entérite , Incidence , Corée , Shigella flexneri , Shigella sonnei , ShigellaRésumé
Multilocus sequence typing (MLST) of Salmonella is useful method for replacing serotyping using antisera but is limited by difficulties associated with in polymerase chain reaction (PCR). We optimized the PCR reaction, especially annealing temperature and extension time (94degrees C for 2 min; 40 cycles at 94degrees C for 30 sec, 56.8degrees C for 1 min, 72degrees C for 2 min; and 72degrees C for 10 min). The degradation of PCR product by thermostable nucleases was inhibited by using template DNAs treated proteinase K or purified by a commercialized preparation kit. The resulting modified MLST was used as accurate and fast typing method.
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ADN , Endopeptidase K , Sérums immuns , Typage par séquençage multilocus , Réaction de polymérisation en chaîne , Salmonella , SérotypieRésumé
Burkholderia pseudomallei is a gram-negative opportunistic intracellular pathogen that causes an acute and fatal septicemic melioidosis in humans. The organism is mainly found in Southeastern Asia and Northern Australia. Recently, we encountered a case of melioidosis in a Korean patient and performed the laboratory diagnosis of melioidosis. As a result, a gram negative bacterium was isolated from a melioidosis patient, and it was identified as B. pseudomallei on DNA sequencing of 16S ribosomal RNA with 99.9% homology and biochemical examination of VITEK gram-negative identification card. Also, DNA from cultured bacteria was tested in multiplex PCR, a 245 bp fragment amplified from the metalloprotease gene and a fragment of variable size ranging from 400~700 bp resulting from amplification of the 10 bp repetitive element for B. pseudomallei were confirmed after electrophoresis. The bacterium was sensitive to ceftazidime, imipenem and meropenem but resistant to ticarcillin. So far, there are no domestic cases of melioidosis in Korea, however, due to the increase in international travelers, the incidence of melioidosis is likely to increase. We report a recent case of melioidosis in a Korean patient.
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Humains , Asie du Sud-Est , Australie , Bactéries , Burkholderia pseudomallei , Ceftazidime , Techniques de laboratoire clinique , ADN , Électrophorèse , Imipénem , Incidence , Corée , Mélioïdose , Réaction de polymérisation en chaine multiplex , ARN ribosomique 16S , Analyse de séquence d'ADN , Thiénamycine , TicarcillineRésumé
Botulinum neurotoxin type A (BoNT/A) is a metalloprotease that cleaves SNAP-25 (synaptosome-associated protein of 25 kDa), a specific cellular protein essential for neurotransmitter release. As well as mouse bioassay to detect BoNT/A, various assay methods based on its endopeptidase activity have been developed. In this study, we tried to develop a BoNT/A assay system using recombinant SNAP-25 with glutathione S-transferase (GST) tags at both termini as substrate. The recombinant GST-SNAP-25-GST with 70 kDa was expressed and purified in E. coli and synthesized N-terminal 50 kDa and C-terminal 25 kDa fragment after cleavage at the Gln(197)-Arg(198) bond by BoNT/A. To detect both fragments, we obtained rabbit antisera against peptides corresponding to the cleaved ends of each fragment. In the western blotting, the N-terminal fragment was detected by the antibody specifically recognizing the newly exposed C-terminus (corresponding to amino acid residue 191-197). This assay system was able to detect until 3.125 ng of BoNT/A, which corresponded to about 90 fold LD50 in mice. These results suggest that the in vitro endopeptidase assay developed in this study would replace others to detect BoNT/A.
Sujets)
Animaux , Souris , Dosage biologique , Technique de Western , Glutathione transferase , Sérums immuns , Dose létale 50 , Agents neuromédiateurs , PeptidesRésumé
Botulinum neurotoxin type A (BoNT/A) is a metalloprotease that cleaves SNAP-25 (synaptosome-associated protein of 25 kDa), a specific cellular protein essential for neurotransmitter release. As well as mouse bioassay to detect BoNT/A, various assay methods based on its endopeptidase activity have been developed. In this study, we tried to develop a BoNT/A assay system using recombinant SNAP-25 with glutathione S-transferase (GST) tags at both termini as substrate. The recombinant GST-SNAP-25-GST with 70 kDa was expressed and purified in E. coli and synthesized N-terminal 50 kDa and C-terminal 25 kDa fragment after cleavage at the Gln(197)-Arg(198) bond by BoNT/A. To detect both fragments, we obtained rabbit antisera against peptides corresponding to the cleaved ends of each fragment. In the western blotting, the N-terminal fragment was detected by the antibody specifically recognizing the newly exposed C-terminus (corresponding to amino acid residue 191-197). This assay system was able to detect until 3.125 ng of BoNT/A, which corresponded to about 90 fold LD50 in mice. These results suggest that the in vitro endopeptidase assay developed in this study would replace others to detect BoNT/A.
Sujets)
Animaux , Souris , Dosage biologique , Technique de Western , Glutathione transferase , Sérums immuns , Dose létale 50 , Agents neuromédiateurs , PeptidesRésumé
Botulism is a rare neuroparalytic disease caused by neurotoxins of Clostridium species. A ten-year-old girl and her mother were admitted to a hospital with symptoms of progressive dizziness, blurred vision, slurred speech, constipation and difficulty in swallowing. These characteristic manifestations and clinical course prompted an examination of the possibility of botulism. Mouse bioassay performed with mother's stool demonstrated type A botulinum toxin and culture of the mother's stool was positive for Clostridium botulinum type A. This is the first case of botulism in Korea.
Sujets)
Animaux , Femelle , Humains , Souris , Dosage biologique , Toxines botuliniques , Botulisme , Clostridium , Clostridium botulinum , Clostridium botulinum type A , Constipation , Déglutition , Sensation vertigineuse , Corée , Mères , NeurotoxinesRésumé
We compared genetic variations in virulence mega plasmids pXO1 and pXO2 of twenty-seven Bacillus anthracis strains from Korean patients and environmental samples together with those of Bacillus anthracis Sterne, Pasteur and A2012 standard strains. Genetic variations were analyzed in twenty-three variable regions (ten and thirteen variablenumber tandem repeats and insertion/deletions in pXO1 and pXO2, respectively). The pXO1 plasmids were classified into 7 groups and pXO2 plasmids to 12 groups. Discrete phylogenic lineages could be differentiated between environmental and clinical strains by UPGMA (unweighted pair group method with average) method. In addition, clinical strains showed more variations than environmental isolates. The pXO2 plasmid appeared genetically more unstable than pXO1. A general plasmid genotype could be suggested for Korean soil isolates since they mostly clustered into a representative group.