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BACKGROUND Understanding the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be a useful tool when studying spread of the disease. This study aimed to compare the prevalence of antibodies to SARS-CoV-2 in 9954 recruits in the Korean Army Training Center with the general Korean population age <30 years between September and November, 2020. MATERIAL AND METHODS At the Korean Army Training Center, samples were taken from 9954 men from September to November, 2020. Participants were randomly enlisted healthy adult men. The data were compared with 4,205,265 samples from the Korean general population. Men age <30 years were used, as this is similar to the age range of the military recruits. RESULTS Among military recruits, 31 subjects (0.31%) were positive for the antibody, while the Korean male population had 3757 (0.09%) positive individuals. Among these 31 men, 13 were previously diagnosed by PCR, while 18 (58.06%) had no history related to the disease. Positive military recruits were mostly from 2 regional clusters. The first cluster was Daegu and Gyeongbuk areas (1.97% and 0.80%, respectively), which had an outbreak in March, 2020. The second cluster was Gyeonggi and Seoul, or capital areas (0.23% and 0.20%, respectively), which currently has high PCR positivity. Overall, seroprevalence was 3.49 times higher in study subjects. CONCLUSIONS The high seroprevalence of antibodies to SARS-CoV-2 between September and November 2020 in a densely populated military academy in Korea may have been an indicator for the resulting outbreak of COVID-19 in winter 2020-21, which highlights the importance of asymptomatic spread from the young and healthy to the general population.
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COVID-19 , Militares , Adulto , COVID-19/epidemiologia , Feminino , Humanos , Imunoglobulina G , Masculino , Prevalência , SARS-CoV-2 , Estudos SoroepidemiológicosRESUMO
BACKGROUND: Enterovirus (EV) 71 is the main pathogen associated with hand, foot and mouth disease (HFMD) or herpangina. Outbreaks of HFMD caused by EV71 infection are associated severe neurological disease and high mortality rates in children. Several sporadic cases of EV71 infection occurred in the Republic of Korea (ROK) in 2000, and EV71 infections were not reported thereafter until 2006. In this prospective study, we report the epidemic and virologic characteristics of the EV71 endemic from 2007 to 2012 in the Republic of Korea. METHODS: We analyzed characteristics of the EV71 infection-associated epidemic from collected specimens and clinical information from 9987 patients with suspected EV infection from the National EV Surveillance System in ROK. To identify the EV71 subgenotype, the homology of viral protein 1 sequences obtained using reverse transcription polymerase chain reaction was compared with the sequences on other countries available from GenBank database. RESULTS: EV71 was detected in 585 (16.7 %) specimens (cerebrospinal fluid, stool or rectal swabs, throat swabs and blood) during study period and was most frequently observed during epidemic seasons in 2009-2012. Major manifestations due to EV71 infection were HFMD (62.2 %) and HFMD with severe neurological complications (28.4 %). Five deaths (0.9 %) due to EV71 infection occurred, with an increased mortality rate during the period after 2009. Most patients (476; 81.4 %) were less than 5 years of age. Analysis of the monthly distribution showed that there was an obvious seasonal pattern to the epidemics, with infections appearing from June to August. The major subgenotype of EV71 isolates circulating in ROK was the C4a strain, which has also appeared in China, Japan and Vietnam. CONCLUSIONS: This surveillance provided valuable data on the epidemic characteristics of EV71 infections in ROK during a 6-year period. Our findings provide data to assist during future outbreaks of EV71 and associated acute neurologic disease.
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Enterovirus Humano A/genética , Doença de Mão, Pé e Boca/epidemiologia , Adolescente , Adulto , Líquido Cefalorraquidiano/virologia , Criança , Pré-Escolar , Estudos Transversais , Surtos de Doenças , Enterovirus Humano A/classificação , Enterovirus Humano A/isolamento & purificação , Fezes/virologia , Feminino , Genótipo , Doença de Mão, Pé e Boca/mortalidade , Doença de Mão, Pé e Boca/virologia , Humanos , Lactente , Masculino , Filogenia , RNA Viral/isolamento & purificação , RNA Viral/metabolismo , República da Coreia/epidemiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Taxa de Sobrevida , Proteínas Virais/genética , Proteínas Virais/metabolismo , Adulto JovemRESUMO
BACKGROUND: Enteroviruses (EVs) are the leading cause of aseptic meningitis worldwide. Detection of enteroviral RNA in clinical specimens has been demonstrated to improve the management of patient care, especially that of neonates and young children. FINDINGS: To establish a sensitive and reliable assay for routine laboratory diagnosis, we compared the sensitivity and specificity of the GeneXpert Enterovirus Assay (GXEA) with that of the reverse transcription polymerase chain reaction (RT-PCR) based assay referred to as real-time one step RT-PCR (RTo-PCR). The sensitivity/specificity produced by GXEA and RTo-PCR were 100%/100% and 65%/100%, respectively. CONCLUSIONS: Both methods evaluated in this article can be used for detection of enterovirus in clinical specimens and these nucleic acid amplification methods are useful assays for the diagnosis of enteroviral infection.
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Infecções por Enterovirus/virologia , Enterovirus/isolamento & purificação , Meningite/virologia , RNA Viral/genética , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Enterovirus/genética , Infecções por Enterovirus/líquido cefalorraquidiano , Infecções por Enterovirus/diagnóstico , Humanos , Meningite/líquido cefalorraquidiano , Meningite/diagnóstico , Técnicas de Diagnóstico Molecular , RNA Viral/líquido cefalorraquidianoRESUMO
BACKGROUND: Although age negatively correlates with vaccine-induced immune responses, whether the vaccine-induced neutralizing effect against variants of concern (VOCs) substantially differs across age remains relatively poorly explored. In addition, the utility of commercial binding assays developed with the wild-type SARS-CoV-2 for predicting the neutralizing effect against VOCs should be revalidated. METHODS: We analyzed 151 triple-vaccinated SARS-CoV-2-naïve individuals boosted with BNT162b2 (Pfizer-BioNTech). The study population was divided into young adults (age < 30), middle-aged adults (30 ≤ age < 60), and older adults (age ≥ 60). The plaque reduction neutralization test (PRNT) titers against Delta (B.1.617.2) and Omicron (B.1.1.529) variants were compared across age. Antibody titers measured with commercial binding assays were compared with PRNT titers. RESULTS: Age-related decline in neutralizing titers was observed for both Delta and Omicron variants. Neutralizing titers for Omicron were lower than those against Delta in all ages. The multiple linear regression model demonstrated that duration from third dose to sample collection and vaccine types were also significant factors affecting vaccine-induced immunity along with age. The correlation between commercial binding assays and PRNT was acceptable for all age groups with the Delta variant, but relatively poor for middle-aged and older adults with the Omicron variant due to low titers. CONCLUSIONS: This study provides insights into the age-related dynamics of vaccine-induced immunity against SARS-CoV-2 VOCs, corroborating the need for age-specific vaccination strategies in the endemic era where new variants continue to evolve. Moreover, commercial binding assays should be used cautiously when estimating neutralizing titers against VOCs, particularly Omicron.
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Anticorpos Neutralizantes , Anticorpos Antivirais , Vacina BNT162 , COVID-19 , SARS-CoV-2 , Humanos , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/sangue , SARS-CoV-2/imunologia , Adulto , Pessoa de Meia-Idade , COVID-19/imunologia , COVID-19/prevenção & controle , COVID-19/virologia , Masculino , Feminino , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Vacina BNT162/imunologia , Vacina BNT162/administração & dosagem , Idoso , Fatores Etários , Adulto Jovem , Testes de Neutralização/métodos , Vacinas contra COVID-19/imunologia , Vacinas contra COVID-19/administração & dosagemRESUMO
Background: The assessment of long-term humoral and cellular immunity post-vaccination is crucial for establishing an optimal vaccination strategy. Methods: This prospective cohort study evaluated adults (≥18 years) who received a BA.4/5 bivalent vaccine. We measured the anti-receptor binding domain immunoglobulin G antibody and neutralizing antibodies (NAb) against wild-type and Omicron subvariants (BA.5, BQ.1.1, BN.1, XBB.1 and EG.5) up to 9 months post-vaccination. T-cell immune responses were measured before and 4 weeks after vaccination. Results: A total of 108 (28 SARS-CoV-2-naïve and 80 previously infected) participants were enrolled. Anti-receptor binding domain immunoglobulin G (U/mL) levels were higher at 9 months post-vaccination than baseline in SAR-CoV-2-naïve individuals (8,339 vs. 1,834, p<0.001). NAb titers against BQ.1.1, BN.1, and XBB.1 were significantly higher at 9 months post-vaccination than baseline in both groups, whereas NAb against EG.5 was negligible at all time points. The T-cell immune response (median spot forming unit/106 cells) was highly cross-reactive at both baseline (wild-type/BA.5/XBB.1.5, 38.3/52.5/45.0 in SARS-CoV-2-naïve individuals; 51.6/54.9/54.9 in SARS-CoV-2-infected individuals) and 4 weeks post-vaccination, with insignificant boosting post-vaccination. Conclusion: Remarkable cross-reactive neutralization was observed against BQ.1.1, BN.1, and XBB.1 up to 9 months after BA.4/5 bivalent vaccination, but not against EG.5. The T-cell immune response was highly cross-reactive.
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Anticorpos Neutralizantes , Anticorpos Antivirais , Vacinas contra COVID-19 , COVID-19 , Imunidade Celular , Imunidade Humoral , SARS-CoV-2 , Vacinação , Humanos , Masculino , COVID-19/imunologia , COVID-19/prevenção & controle , SARS-CoV-2/imunologia , Feminino , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Vacinas contra COVID-19/imunologia , Vacinas contra COVID-19/administração & dosagem , Pessoa de Meia-Idade , Adulto , Estudos Prospectivos , Idoso , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Linfócitos T/imunologiaRESUMO
OBJECTIVES: Concomitant COVID-19 and influenza vaccination would be an efficient strategy. Although the co-administration of monovalent COVID-19 and influenza vaccinations showed acceptable immunogenicity, it remains unknown whether the bivalent COVID-19 vaccine could intensify immune interference. We aimed to evaluate the immunogenicity and safety of concomitant BA.5-based bivalent COVID-19 and influenza vaccination. METHODS: An open-label, nonrandomized clinical trial was conducted for 154 age-matched and sex-matched healthy adults between October 2022 and December 2022. Participants received either a concomitant bivalent COVID-19 mRNA booster and quadrivalent influenza vaccination (group C) or separate vaccinations (group S) at least 4 weeks apart. Solicited and unsolicited adverse events were reported up to 6 months postvaccination. Immunogenicity was evaluated by anti-spike (S) IgG electrochemiluminescence immunoassay, focus reduction neutralization test, and hemagglutination inhibition assay. RESULTS: Group C did not meet the noninferiority criteria for the seroconversion rates of anti-S IgG and neutralizing antibodies against the wild-type SARS-CoV-2 strain compared with group S (44.2% vs. 46.8%, difference of -2.6% [95% CI, -18 to 13.4]; 44.2% vs. 57.1%, difference of -13.0% [95% CI to -28.9 to 2.9]). However, group C showed a stronger postvaccination neutralizing antibody response against Omicron BA.5 (72.7% vs. 64.9%). Postvaccination geometric mean titers for SARS-CoV-2 and influenza strains were similar between groups, except for influenza B/Victoria. Most adverse events were mild and comparable between the study groups. DISCUSSION: Concomitant administration of bivalent COVID-19 mRNA and quadrivalent influenza vaccines showed tolerable safety profiles and sufficient immunogenicity, particularly attenuating immune imprinting induced by previous ancestral vaccine strains.
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Anticorpos Neutralizantes , Anticorpos Antivirais , Vacinas contra COVID-19 , COVID-19 , Imunogenicidade da Vacina , Vacinas contra Influenza , Influenza Humana , SARS-CoV-2 , Humanos , Masculino , Feminino , Vacinas contra Influenza/imunologia , Vacinas contra Influenza/efeitos adversos , Vacinas contra Influenza/administração & dosagem , Anticorpos Antivirais/sangue , COVID-19/prevenção & controle , COVID-19/imunologia , Adulto , Vacinas contra COVID-19/imunologia , Vacinas contra COVID-19/efeitos adversos , Vacinas contra COVID-19/administração & dosagem , SARS-CoV-2/imunologia , Anticorpos Neutralizantes/sangue , Pessoa de Meia-Idade , Influenza Humana/prevenção & controle , Influenza Humana/imunologia , Vacinação , Imunoglobulina G/sangue , Adulto Jovem , Imunização SecundáriaRESUMO
The unwanted detachment of organs such as flowers, leaves, and fruits from the main body of a plant (abscission) has significant effects on agricultural practice. Both timely and precise regulation of organ abscission from a plant is crucial as it influences the agricultural yield. The tomato (Solanum lycopersicum) has become a model system for research on organ abscission. Here, we characterized four tomato natural abscission variants named jointless (j), functionally impaired jointless (fij), functionally impaired jointless like (fij like), and normal joint (NJ), based on their cellular features within the flower abscission zones (AZ). Using eight INFLORESCENCE DEFICIENT IN ABSCISSION (SlIDA) genes and eight HAESA genes (SlHAE) identified in the genome sequence of tomato, we analyzed the pattern of gene expression during flower abscission. The AZ-specific expression for three tomato abscission polygalacturonases (SlTAPGs) in the development of flower AZ, and the progression of abscission validated our natural abscission system. Compared to that of j, fij, and fij like variants, the AZ-specific expression for SlIDA, SlIDL2, SlIDL3, SlIDL4, and SlIDL5 in the NJ largely corelated and increased with the process of abscission. Of eight SlHAE genes examined, the expression for SlHSL6 and SlHSL7 were found to be AZ-specific and increased as abscission progressed in the NJ variant. Unlike the result of gene expression obtained from natural abscission system, an in silico analysis of transcriptional binding sites uncovered that SlIDA genes (SlIDA, SlIDL6, and SlIDL7) are predominantly under the control of environmental stress, while most of the SlHSL genes are affiliated with the broader context in developmental processes and stress responses. Our result presents the potential bimodal transcriptional regulation of the tomato IDA-HAE module associated with flower abscission in tomatoes.
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Mumps is an acute infectious disease caused by the mumps virus (MuV). Despite high global vaccination coverage, mumps outbreaks continue to occur, even in vaccinated populations. Therefore, we aimed to identify candidate vaccines that can induce an immunogenic response against diverse MuV genotypes with greater efficacy than the currently available options. Vaccine candidates were sourced using formalin-inactivated viral strains. The inactivated vaccines were administered to BALB/c mice (through a primer and booster dose administered after a three-week interval). We tested the neutralizing antibodies of the candidate vaccines against various MuV genotypes to determine their overall efficacy. The formalin-inactivated F genotype vaccine was found to have higher cross-neutralizing titers against genotypes F, H, and G as well as significant Th1 cytokines responses, IFN-γ, TNF-α, and IL-2 than the Jeryl Lynn (JL) vaccine. Our findings suggest that the inactivated F genotype mumps vaccine has higher immunogenicity than the JL vaccine against diverse circulating MuVs.
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Background: Humoral immune responses and infection risk after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) vaccination during the Omicron BA.5 and BN.1 variants predominant period remains unexplored in pediatric population. Methods: We examined anti-spike (anti-S) immunoglobulin G (IgG) responses in a total of 986 children aged 4-18 years who visited outpatient clinics between June 2022 and January 2023, with a history of SARS-CoV-2 infection alone, completed two doses of COVID-19 vaccination alone, vaccine-breakthrough infection (i.e., infection after the single dose of vaccination), and no antigenic exposure. Furthermore, to determine SARS-CoV-2 infection risk, the incidence of newly developed SARS-CoV-2 infection was investigated up to March 2023. Results: The anti-S IgG levels in the 'vaccine-breakthrough infection' group exceeded those in the 'infection alone' and 'vaccination alone' groups (both P <0.01). Furthermore, the 'vaccination alone' group experienced more rapid anti-S IgG waning than the 'infection alone' and 'vaccine-breakthrough infection' groups (both P <0.01). We could not identify newly developed SARS-CoV-2 infection in the 'vaccine-breakthrough infection' group. Conclusion: Our findings suggest that hybrid immunity, acquired from SARS-CoV-2 infection and COVID-19 vaccination, was a potentially higher and longer-lasting humoral immune response and protected against SARS-CoV-2 infection in pediatric population during Omicron BA.5 and BN.1 variants predominant.
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COVID-19 , SARS-CoV-2 , Humanos , Criança , COVID-19/epidemiologia , COVID-19/prevenção & controle , Imunidade Humoral , Infecções Irruptivas , Vacinas contra COVID-19 , República da Coreia/epidemiologia , Vacinação , Imunoglobulina GRESUMO
Bivalent COVID-19 vaccines that contain BA.1 or BA.4/BA.5 have been introduced worldwide in response to pandemic waves of Omicron subvariants. This prospective cohort study was aimed to compare neutralizing antibodies (Nabs) against Omicron subvariants (BA.1, BA.5, BQ.1.1, BN.1, and XBB.1) before and 3-4 weeks after bivalent booster by the types of SARS-CoV-2 variants in prior infections and bivalent vaccine formulations. A total of 21 participants were included. Prior BA.1/BA.2-infected, and BA.5-infected participants showed significantly higher geometric mean titers of Nab compared to SARS-CoV-2-non-infected participants after bivalent booster (BA.1, 8156 vs. 4861 vs. 1636; BA.5, 6515 vs. 4861 vs. 915; BQ.1.1, 697 vs. 628 vs. 115; BN.1, 1402 vs. 1289 vs. 490; XBB.1, 434 vs. 355 vs. 144). When compared by bivalent vaccine formulations, Nab titers against studied subvariants after bivalent booster did not differ between BA.1 and BA.4/BA.5 bivalent vaccine (BA.1, 4886 vs. 5285; BA.5, 3320 vs. 4118; BQ.1.1, 311 vs. 572; BN.1, 1028 vs. 1095; XBB.1, 262 vs. 362). Both BA.1 and BA.4/BA.5 bivalent vaccines are immunogenic and provide enhanced neutralizing activities against Omicron subvariants. However, even after the bivalent booster, neutralizing activities against the later Omicron strains (BQ.1.1, BN.1, and XBB.1) would be insufficient to provide protection.
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The immunogenicity of a heterologous vaccination regimen consisting of ChAdOx1 nCoV-19 (a chimpanzee adenovirus-vectored vaccine) followed by mRNA-1273 (a lipid-nanoparticle-encapsulated mRNA-based vaccine) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), specifically the omicron variant (B.1.1.529), is poorly studied. The aim of this study was to evaluate the neutralizing antibody activity and immunogenicity of heterologous ChAdOx1 nCoV-19 and mRNA-1273 prime-boost vaccination against wild-type (BetaCoV/Korea/KCDC03/2020), alpha, beta, gamma, delta, and omicron variants of SARS-CoV-2 in Korea. A 50% neutralizing dilution (ND50) titer was determined in serum samples using the plaque reduction neutralization test. Antibody titer decreased significantly at 3 months compared with that at 2 weeks after the 2nd dose. On comparing the ND50 titers for the above-mentioned variants of concerns, it was observed that the ND50 titer for the omicron variant was the lowest. This study provides insights into cross-vaccination effects and can be useful for further vaccination strategies in Korea.
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OBJECTIVES: We estimated the population prevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including unreported infections, through a Korea Seroprevalence Study of Monitoring of SARS-CoV-2 Antibody Retention and Transmission (K-SEROSMART) in 258 communities throughout Korea. METHODS: In August 2022, a survey was conducted among 10,000 household members aged 5 years and older, in households selected through two stage probability random sampling. During face-to-face household interviews, participants self-reported their health status, COVID-19 diagnosis and vaccination history, and general characteristics. Subsequently, participants visited a community health center or medical clinic for blood sampling. Blood samples were analyzed for the presence of antibodies to spike proteins (anti-S) and antibodies to nucleocapsid proteins (anti-N) SARS-CoV-2 proteins using an electrochemiluminescence immunoassay. To estimate the population prevalence, the PROC SURVEYMEANS statistical procedure was employed, with weighting to reflect demographic data from July 2022. RESULTS: In total, 9,945 individuals from 5,041 households were surveyed across 258 communities, representing all basic local governments in Korea. The overall population-adjusted prevalence rates of anti-S and anti-N were 97.6% and 57.1%, respectively. Since the Korea Disease Control and Prevention Agency has reported a cumulative incidence of confirmed cases of 37.8% through July 31, 2022, the proportion of unreported infections among all COVID-19 infection was suggested to be 33.9%. CONCLUSIONS: The K-SEROSMART represents the first nationwide, community-based seroepidemiologic survey of COVID-19, confirming that most individuals possess antibodies to SARS-CoV-2 and that a significant number of unreported cases existed. Furthermore, this study lays the foundation for a surveillance system to continuously monitor transmission at the community level and the response to COVID-19.
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COVID-19 , SARS-CoV-2 , Humanos , Estudos Soroepidemiológicos , Teste para COVID-19 , COVID-19/epidemiologia , Anticorpos Antivirais , República da Coreia/epidemiologiaRESUMO
OBJECTIVES: The Korea National Health and Nutrition Examination Survey (KNHANES) is a nationwide cross-sectional surveillance system that assesses the health and nutritional status of the Korean population. To evaluate the occurrence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the community, we investigated the prevalence of anti-SARS-CoV-2 antibodies in the sera of KNHANES participants. METHODS: Subjects were recruited between April 24 and December 12, 2020. In total, 5,284 subjects aged 10-90 years from 17 regions participated. SARS-CoV-2 antibodies were screened using the Elecsys Anti-SARS-CoV-2 assay. Positive samples were verified using 4 different SARS-CoV-2 antibody assays and the plaque reduction neutralizing test. The final seropositivity criteria were a positive screening test and at least 1 positive result from the 5 additional tests. RESULTS: Almost half (49.2%; 2,600/5,284) of participants were from metropolitan areas, 48.9% were middle-aged (40-69 years), and 20.5% were in their 20s or younger. The seropositivity rate was 0.09% (5/5,284). Three of the 5 antibody-positive subjects had a history of infection, of whom 2 were infected abroad and 1 was infected in a local cluster outbreak. CONCLUSIONS: The low SARS-CoV-2 antibody seroprevalence in Korea indicates that there have been few coronavirus disease 2019 (COVID-19) cases due to successful COVID-19 management measures (e.g., diagnostic tests for overseas arrivals, national social distancing, and strict quarantine measures). Moreover, asymptomatic infections were uncommon due to active polymerase chain reaction testing. However, hidden infections may exist in the community, requiring the continuation of quarantine and vaccination measures.
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COVID-19 , SARS-CoV-2 , Adulto , Idoso , Anticorpos Antivirais , COVID-19/epidemiologia , Estudos Transversais , Humanos , Pessoa de Meia-Idade , Inquéritos Nutricionais , República da Coreia , Estudos SoroepidemiológicosRESUMO
Japanese encephalitis is prevalent throughout the temperate and tropical regions of Asia and is caused by the Japanese encephalitis virus (JEV), a mosquito-borne viral pathogen. The plaque reduction neutralization test (PRNT) is currently recommended as the gold standard test for detecting human antibodies against JEV. The plaque assay is the most widely used method for detecting infectious virions and involves counting discrete plaques in cells. However, it is time-consuming, and results can be subjective (owing to analyst variability during manual plaque counting). The focus reduction neutralization test (FRNT), which is based on an immuno-colorimetric assay, can be used to automatically count foci formed by the JEV. Here, we compared the efficacy of PRNT and FRNT in measuring the neutralizing antibody titers using 102 serum samples from vaccinated and unvaccinated individuals. We observed positive correlations between these neutralization assays against the Nakayama and Beijing strains (R2 = 0.98 and 0.77, respectively). Thus, FRNT may be preferable to PRNT for evaluating the efficacy of JEV vaccines in large-scale serological studies.
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Vírus da Encefalite Japonesa (Espécie) , Vírus da Encefalite Japonesa (Subgrupo) , Encefalite Japonesa , Animais , Anticorpos Neutralizantes , Anticorpos Antivirais , Encefalite Japonesa/diagnóstico , Humanos , Testes de Neutralização/métodos , Ensaio de Placa ViralRESUMO
OBJECTIVES: After the third wave of coronavirus disease 2019 (COVID-19), by mid-February 2021, approximately 0.16% of the Korean population was confirmed positive, which appeared to be among the lowest rates worldwide at that time. However, asymptomatic transmission is challenging for COVID-19 surveillance. Therefore, a community-based serosurvey of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was conducted to understand the effectiveness of Korea's strong containment strategy. METHODS: We collected 5,002 residual sera samples from January 30 to March 3, 2021, from 265 medical facilities in Seoul, 346 in Gyeonggi Province, and 57 in Incheon. Sixty samples from tertiary institutions were excluded. We defined the sub-regions according to the addresses of the medical facilities where the specimens were collected. Elecsys Anti-SARS-CoV-2 was used for screening, and positivity was confirmed using the SARS-CoV-2 sVNT Kit. Prevalence was estimated using sampling weights and the Wilson score interval for a binomial proportion with a 95% confidence interval. RESULTS: Among the 4,942 specimens, 32 and 25 tested positive for COVID-19 in the screening and confirmatory tests, respectively. The overall crude prevalence of SARS-CoV-2 antibodies was 0.51%. The population-adjusted overall prevalence was 0.55% in women and 0.38% in men. The region-specific estimation was 0.67% and 0.30% in Gyeonggi Province and Seoul, respectively. No positive cases were detected in Incheon. CONCLUSIONS: The proportion of undetected cases in Korea remained low as of early 2021. Therefore, an infection control strategy with exhaustive tracing and widespread pre-emptive testing appears to be effective in containing community spread of COVID-19.
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Teste Sorológico para COVID-19 , COVID-19 , Humanos , Feminino , Estudos Soroepidemiológicos , COVID-19/epidemiologia , Seul/epidemiologia , SARS-CoV-2 , Anticorpos AntiviraisRESUMO
BACKGROUND: Seroprevalence studies of coronavirus disease 2019 (COVID-19) cases, including asymptomatic and past infections, are important to estimate the scale of the disease outbreak and to establish quarantine measures. We evaluated the clinical performance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody assays available in Korea for use in seroprevalence studies. METHODS: The sensitivity, specificity, cross-reactivity, and interference of five SARS-CoV-2 antibody assays were evaluated using the following: 398 serum samples from confirmed COVID-19 patients, 510 negative control samples from before 2018 (pre-pandemic), 163 serum samples from patients with SARS, Middle East respiratory syndrome (MERS), and other viral infections, and five samples for the interference study. RESULTS: The sensitivities of the five assays ranged from 92.2% to 98%, and their specificities, including cross-reactivity and interference, ranged from 97.5% to 100%. The agreement rates were excellent (kappa >0.9). Adjustment of the cutoff values could be considered through ROC curve analysis. The positive predictive values of the individual assays varied from 3.5% to 100% at a 0.1% prevalence but were as high as ≥95% when two assays were combined. CONCLUSIONS: The prevalence of COVID-19 in Korea is considered to be exceptionally low at present; thus, we recommend using a combination of two or more SARS-CoV-2 antibody assays rather than a single assay. These results could help select SARS-CoV-2 antibody assays for COVID-19 seroprevalence studies in Korea.
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COVID-19 , SARS-CoV-2 , Anticorpos Antivirais , Humanos , Pandemias , Sensibilidade e Especificidade , Estudos SoroepidemiológicosRESUMO
The risk of polio importation and re-emergence persists since epidemic polio still occurs in some countries, and the resurgence of polio occurring almost 20 years after polio eradication was declared in Asia has been reported. We analyzed the results of acute flaccid paralysis (AFP) surveillance in Korea to assess the quality of AFP surveillance and understand the etiology of non-polio enterovirus (NPEV)-associated central nervous system diseases in a polio-free area. We investigated 637 AFP patients under 15 years of age whose cases were confirmed during 2012-2019 by virus isolation, real-time reverse transcription polymerase chain reaction, and VP1 gene sequencing. Among the 637 AFP cases, NPEV was detected in 213 (33.4%) patients, with the majority observed in EV-A71, with 54.9% of NPEV positives. EV-A71 has been shown to play a role as a major causative agent in most neurological diseases except for Guillain-Barré syndrome (GBS), acute disseminated encephalomyelitis (ADEM), and meningitis. This study provides information on the AFP surveillance situation in Korea and highlights the polio eradication stage in the monitoring and characterization of NPEV against the outbreak of neurological infectious diseases such as polio.
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Viroses do Sistema Nervoso Central , Enterovirus/isolamento & purificação , Monitoramento Epidemiológico , Mielite , Doenças Neuromusculares , Adolescente , Viroses do Sistema Nervoso Central/epidemiologia , Viroses do Sistema Nervoso Central/virologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Mielite/epidemiologia , Mielite/virologia , Doenças Neuromusculares/epidemiologia , Doenças Neuromusculares/virologia , República da Coreia/epidemiologiaRESUMO
Mumps is a contagious disease caused by the mumps virus. It can be prevented using mumps vaccines, administered as a measles-mumps-rubella (MMR) vaccine. For first and second dose immunization, children aged 12-15â¯months and 4-6â¯years have been administered this vaccine since 1997 in Korea. Nevertheless, mumps outbreaks still occur in vaccinated populations worldwide. Hence, immunity against these diseases may be attenuated, or there are antigenic differences between currently available vaccine strains and circulating wild-type viruses. After the introduction of national immunization programs in Korea, mumps cases became sporadic. Viral genotypes F, H, and I have emerged since 1998 whereas the vaccine strains belong to genotype A. Here, we compared the amino acid sequences of the haemagglutinin-neuraminidase (HN) gene from wild-type viruses and the mumps vaccine and measured the cross-neutralization titers between them. We selected the F, H, and I wild-type mumps strains circulating in Korea from 1998 to 2016 and analyzed changes in the amino acid sequence of the protein encoded by the HN gene. We measured mumps virus-specific IgG and rapid focus reduction neutralization test (FRNT) titers in Korean isolates and sera obtained from 50 children aged 1-2â¯years who had been administered a single dose of MMR vaccine. Analysis of the HN protein sequences disclosed no changes in the glycosylation sites but did reveal 4-5 differences between the Korean isolates and the genotype A vaccine strain in terms of the neutralizing epitope sites on their HN proteins. Post-vaccination FRNT titers were significantly lower against genotypes F, H, and I than they were against genotype A. This finding highlights the possibility of a recurrence of mumps outbreaks in vaccinated populations depending on the degree of genetic conservation of the HN gene. Further research into this issue is needed to prevent the resurgence of mumps.
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Vírus da Caxumba , Caxumba , Anticorpos Antivirais , Criança , Pré-Escolar , Humanos , Lactente , Vacina contra Sarampo-Caxumba-Rubéola , Caxumba/epidemiologia , Caxumba/prevenção & controle , Vacina contra Caxumba , Vírus da Caxumba/genética , Testes de Neutralização , República da CoreiaRESUMO
BACKGROUND: Enteroviruses (EVs) occur frequently worldwide and are known to be associated with a broad spectrum of clinical manifestations from mild syndromes to neurological disease. To understand the epidemiology of EV in Korea, we characterized EV-infected cases during 2012-2019 based on national surveillance. METHODS: We collected specimens from patients with suspected EV infections and analyzed the data using real-time reverse-transcription polymerase chain reaction and VP1 gene sequencing. RESULTS: Among the 18 261 specimens collected, EVs were detected in 6258 (34.3%) cases. Although the most common EV types changed annually, EV-A71, echovirus 30, coxsackievirus B5, coxsackievirus A6, and coxsackievirus A10 were commonly identified. Among the human EVs, the case numbers associated with the 2 major epidemic species (EV-A and EV-B) peaked in the summer. While EV-A species affected 1-year-old children and were associated with herpangina and hand, foot, and mouth disease, EV-B species were mostly associated with neurologic manifestations. The highest incidence of EV-B species was observed in infants aged <12 months. Feces and respiratory specimens were the most predictive of EV infection. Specimens collected within 5 days of symptom onset allowed for timely virus detection. CONCLUSIONS: EV-A and EV-B species co-circulating in Korea presented different epidemiologic trends in clinical presentation, affected subjects, and seasonality trends. This study could provide information for the characterization of EVs circulating in Korea to aid the development of EV antivirals and vaccines, as well as public health measures to control enteroviral diseases.
Assuntos
Infecções por Enterovirus , Enterovirus , Doença de Mão, Pé e Boca , Criança , Enterovirus/genética , Enterovirus Humano B , Infecções por Enterovirus/epidemiologia , Humanos , Lactente , República da Coreia/epidemiologiaRESUMO
Enterovirus (EV) 71 is the main pathogen associated with hand-foot-mouth disease (HFMD) and can lead to the disease with severe mortality in children. Since 2009, in the Republic of Korea, an outbreak of EV71 C4a infection with neurologic involvement emerged, where in HFMD involvement was identified and central nervous system complications were reported. In this study, EV71 C4a virus-like particles (VLPs) produced by recombinant technology were generated in a baculovirus expression system. To improve the production yield, EV71 VLP was constructed using the dual promoter system baculovirus P1 and 3CD (baculo-P1-3CD), which harbored both the structural protein-encoding P1 region under the control of the polyhedron promoter and the 3CD protease gene under the regulation of the CMV-IE, lef3, gp41, or chitinase promoters to augment the level of gene transcription. Efficient VLP expression was demonstrated through optimization of incubation time and insect cell type. In addition, to evaluate the potential of VLP as a vaccine candidate, we tested the neutralizing antibodies and total anti-EV71 IgG from the purified EV71 C4a VLP serum. The recombinant EV71 VLP exhibited the morphology of self-assembled VLP, as determined by electron microscopy. Use of baculo-P1-3CD-gp41 led to a high yield (11.3mg/L < 40kDa) of VLPs in High-FiveTM cells at 3 days post-infection. Furthermore, the potential of VLP as a vaccine was evaluated through the neutralizing ability elicited by the purified EV71 VLP after immunization of BALB/c mice, which was shown to induce potent and long-lasting humoral immune responses as evidenced by the cross-neutralization titer. Our results could be used to expedite the developmental process for vaccines under clinical trials and to ensure manufacturing consistency for licensing requirements.