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The immunogenicity and protective efficacy of inactivated clade 2.3.2.1c (rgKA435) and clade 2.3.4.4c (rgES2) H5Nx vaccines, which are representatives of an avian influenza antigen bank in Korea, were examined in mice. Mice were vaccinated twice and then challenged with homologous virus. Hemagglutinin inhibition and serum neutralizing antibody titers in the rgES2-vaccinated group were higher (4.4 ± 1.7 and 10.8 ± 2.3 log 2 , respectively) than those in the rgKA435-vaccinated group (2.8 ± 1.1 and 2.5 ± 0.9 log 2 , respectively). rgES2 conferred 100% protection, with no morbidity, no severe body weight loss, and no virus replication in any of the tissues tested. By contrast, 80% of mice in the rgKA435 group survived. One mouse in this group died at 10 dpi. Virus titers in the lung and turbinate were 102.5–3.5 TCID 50 /0.1 ml at 3–7 dpi and 101.5 TCID 50 /0.1 ml at 3–5 dpi, respectively. In particular, the viral titer in the turbinate from the rgKA435 group at 3 dpi was significantly lower than that in the equivalent control group (p < 0.05). The data suggest that both of these antigen bank vaccines are promising candidates for further evaluation in humans. [ABSTRACT FROM AUTHOR]

• Five inactivated vaccines were generated for Korean AI national antigenic bank for HPAI emergency preparedness. • Vaccines provide good protection in SPF chickens against homologous HPAI virus. • Vaccines produce high immunity from a single dose with sufficient antigen mass. • Vaccines induce long-lasting antibody responses to prevent mortality and virus shedding. The occurrence of severe outbreaks of highly pathogenic avian influenza in Korea led to establishment of a national antigen bank for emergency preparedness. Here, we developed five vaccines for this bank (clade 2.3.2.1C, clade 2.3.4.4A, B, C, and D) by reverse genetics, inactivated them with formalin, and evaluated the protective efficacy and potency of serial dilutions against lethal homologous challenge in specific-pathogen-free chickens. After vaccination with one dose, each vaccine resulted in 100% survival, with no clinical symptoms, or lack of detectable virus shedding, and high levels of pre-challenge protective immunity (8.4–10.2 log 2). After vaccination with one-tenth of the full dose, protection was similar to that with the full dose. After vaccination with one-hundredth of the initial dose, survival was 20–80%, and all vaccines showed virus shedding. Four vaccines (excluding clade 2.3.2.1C) had satisfactory potency. In antibody-persistence tests, all vaccines maintained long-lasting protective immunity. Our results suggest that inactivated reverse-genetics vaccines genetically matched to outbreak viruses provide adequate protection after a single vaccination. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a highly fatal viral disease affecting pigs. It is caused by the ASF virus (ASFV), and causes serious economic losses to the swine industry worldwide, including in Korea. Commercially available enzyme-linked immunosorbent assay (ELISA) kits for detecting anti-ASFV antibodies are used for the diagnosis and surveillance of ASF. In this study, an ELISA was developed to detect anti-ASFV antibodies using two recombinant proteins, p22 and p30, from genotype II ASFV. Recombinant transmembrane domain-deleted p22 (p22∆TM) and p30 were expressed in E.coli vector system pET32a and mixed for use as antigens in indirect ELISA. The p22∆TM/p30-based indirect ELISA was validated using 31 sera from genotype I ASFV-infected pigs and 1133 sera from uninfected pigs. Area under the curve of this test was 0.999 [95 % concentration interval 0.992–1.000], and sensitivity and specificity were 93.5 % and 99.8 %, respectively. The between run coefficient of variation for internal quality control serum was 6.61 %. In the seroconversion analysis, the p22∆TM/p30-based indirect ELISA showed equal or better ability to detect antibodies in pigs experimentally challenged with ASFV p72 genotypes I and II (p < 0.05). In conclusion, the p22∆TM/p30-based indirect ELISA is a reliable diagnostic method for detecting anti-ASFV antibodies. • Recombinant transmembrane domain-deleted p22 (p22∆TM) and p30 antigen-based indirect ELISA was developed to detect anti-ASFV antibodies in pigs. • The p22∆TM/p30-based indirect ELISA showed equal or better ability to detect antibodies in pigs experimentally challenged with ASFV p72 genotypes I and II. [ABSTRACT FROM AUTHOR]

Objectives: Beijing strain of Mycobacterium tuberculosis (M. tb) is characterized by a high incidence of transmission, relapse, and drug resistance. This study aimed to determine host immune responses to antigens derived from the Beijing/K strain which has been highly prevalent in tuberculosis (TB) outbreaks in South Korea.Methods: We recruited 52 TB patients and 96 healthy subjects comprising 31 individuals with latent TB infection (LTBI) and 65 TB-naïve controls based on QuantiFERON-TB Gold In-Tube (QFT-IT) tests. Blood samples were obtained for diluted whole-blood assays, multiplex bead arrays, ELISpot assays, and HLA typing. Molecular genotyping of M. tb was performed using clinical isolates.Results: Active TB and LTBI groups were differentiated by TNF-α concentrations induced by the Beijing/K strain-derived antigens, MTBK_24790 and MTBK_24800 (P < 0.001). MTBK_24800-induced IFN-γ and CXCL10 concentrations discriminated the TB-infected groups from TB-naïve controls (P < 0.001). IFN-γ-producing T cells were generated in 87.2% of TB patients in response to MTBK_24800 peptide antigens. The major immunogenic epitope was at C-terminal of the antigen, and predominantly recognized by HLA-DR4 and -DQ4.Conclusions: Measurement of IFN-γ, CXCL10, and TNF-α concentrations induced by MTBK_24790 and MTBK_24800 may contribute to improved diagnosis of TB and vaccine development in regions where the Beijing/K strain is endemic. [ABSTRACT FROM AUTHOR]

Human astroviruses (HAstVs) occur worldwide and are known to the causative agents of diarrhea in infants and elderly patients with immune dysfunction. This study aimed to identify recombinant HAstV strains and characterize rare genotypes. The full-length genome of a recombinant HAstV strain isolated from the stool sample of a patient with acute gastroenteritis from South Korea was amplified using three pairs of previously designed primers and seven newly designed primers. The recombinant HAstV was 6757-bp long and contained three sequential open reading frames (ORFs), designated as ORF1a (2781 bp), ORF1b (1548 bp), and ORF2 (2349 bp). Our findings suggested that a recombination event had occurred between ORF1b and ORF2 of the isolated strain, with a recombination breakpoint at 4081 bp. To our knowledge, this is the first study to reveal the complete nucleotide sequence of a recombinant HAstV strain from South Korea. Our study findings might be useful for identifying other recombinant HAstV strains and for developing vaccines against this pathogenic virus. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the clinical performance of STANDARD F COVID-19 Ag FIA (SD Biosensor Inc., Gyeonggi-do, Republic of Korea), a rapid antigen detection test (RADT) for diagnosing SARS-CoV-2, in patients attended at the Emergency Department with signs or symptoms compatible with COVID-19 that had started in the last 5 days. The clinical performance of the antigen test was compared with RT-PCR, the reference standard. We included 663 specimens from non-repetitive patients. Clinical sensitivity and specificity were 84.0% (95% CI 76.1−89.7) and 99.6% (95% CI 98.5−99.9), respectively. The positive and negative predictive values were 98.1% (95% CI 92.7−99.7) and 96.4% (95% CI 94.4−97.7), respectively. The kappa index agreement between RT-PCR and the RADT was 0.89 (95% CI 0.84−0.93). We concluded that STANDARD F COVID-19 Ag FIA is an excellent first-line RADT method to diagnose symptomatic patients in the emergency department. [ABSTRACT FROM AUTHOR]

Abstract: Raccoon dogs (Nyctereutes procyonoides) are widespread and common in South Korea. In 2011, we obtained serum samples from 102 wild raccoon dogs to survey their exposure to canine distemper virus (CDV). Forty-five of the 102 animals (44.1%) were seropositive. Field cases of canine distemper in wild raccoon dogs from 2010 to 2011 were investigated. Fourteen cases of CDV infection were identified by a commercially available CDV antigen detection kit. These cases were used for virus isolation and molecular analysis. Sequence analysis of hemagglutinin genes indicated that all viruses isolated belonged to the Asia-2 genotype. H protein residues which are related to the receptor and host specificity (residues 530 and 549) were analyzed. A glutamic acid (E) residue is present at 530 in all isolates. At 549, a histidine (H) residue was found in five isolates and tyrosine (Y) residue was found in 6 isolates. Our study demonstrated that CDV infection was widespread in wild raccoon dogs in South Korea. [Copyright &y& Elsevier]

Abstract: Clonorchis sinensis, the causative agent of clonorchiasis, is widespread in East and Southeast Asia, including China, Vietnam and the Republic of Korea. We identified antigenic proteins from adult C. sinensis liver flukes using immunoproteomic analysis. In this study, we found 23 candidate antigenic proteins with a pI in the range of 5.4–6.2 in total lysates of C. sinensis. The antigenic protein spots reacted against sera from clonorchiasis patients and were identified as cysteine proteases, glutathione transferases, gelsolin, propionyl-CoA carboxylase (PCC), prohibitin and 14-3-3 protein (14-3-3) using LC-coupled ESI-MS/MS and an EST database for C. sinensis. PCC and 14-3-3 were identified for the first time as serological antigens for the diagnosis of C. sinensis. To validate the antigenicity of PCC and 14-3-3, recombinant proteins were immunoblotted with sera from clonorchiasis patients. The structural, functional and immunological characteristics of the putative amino acid sequence were predicted by bioinformatics analysis. Our novel finding will contribute to the development of diagnostics for clonorchiasis. These results suggest that immunoproteomic approaches are valuable tools to identify antigens that could be used as targets for effective parasitic infection control strategies. [Copyright &y& Elsevier]

A Korean nationwide surveillance on circulating rotavirus strains was conducted from September 2000 to August 2007 aiming to obtain prevaccine data for predicting vaccine effectiveness. The predominant strains among the 2779 strains analyzed varied annually and only approximately 50% had either a G or a P antigen present in both RotaTeq (Merck & Co. Inc., Whitehouse Station, NJ, USA) and Rotarix (GlaxoSmithKline, Brentford, UK). [ABSTRACT FROM AUTHOR]

We examined the molecular identification of 13 infectious bursal disease virus (IBDV) strains isolated in Korea from January 2009 to January 2010. Sequence analysis of the variable verion protein 2 gene suggested that 3 of the isolates were very virulent IBDV, 8 of the isolates were classical virulent IBDV, 1 of the isolates was antigenic variant IBDV, and 1 of the isolates was intermediate plus vaccine strain. However, the clinical effects were evident for these strains regardless of classification because each chick flock was raised in various field situations with a different vaccine program and complications by other viruses or bacteria. Therefore, our observations revealed that IBDV strains of 4 genotypes, including vaccine strain, were recently present in South Korea and that the IBDV strains need to be discriminated using genetic characterization of virion protein 2 gene for efficient diagnosis arid disease control. [ABSTRACT FROM AUTHOR]

RT-PCR is the gold standard to detect SARS-CoV-2, however, its capacity is limited. We evaluated an automated antigen detection (AAD) test, Elecsys SARS-CoV-2 Antigen (Roche, Germany), for detecting SARS-CoV-2. We compared the limit of detection (LOD) between AAD test, rapid antigen detection (RAD) test; SARS-CoV-2 Rapid Antigen Test (SD Biosensor, Korea), and in-house RT-PCR test. LOD results showed that the AAD test was 100 fold more sensitive than the RAD test, while the sensitivity of the AAD test was comparable to the RT-PCR test. The AAD test detected between 85.7% and 88.6% of RT-PCR-positive specimens collected from COVID-19 patients, false negative results were observed for specimens with Ct values >30. Although clinical sensitivity for the AAD test was not superior or comparable to the RT-PCR test in the present study, the AAD test may be an alternative to RT-PCR test in terms of turn-around time and throughput. [ABSTRACT FROM AUTHOR]

Background Mitochondria have a key role in cell survival, signaling, metabolism, and homeostasis. However, whether their biological properties affected by differentiation status of cells are not well known. This study aimed to compare structural and functional differences of mitochondria between differentiated cancer cells and undifferentiated cancer stem cells. Methods Glioma stem cells (GSCs) were cultured in stem cell culture conditions to maintain their stem cell properties or serum culture conditions to induce their differentiation. Characteristics of GSCs are analyzed through sphere-forming ability and expression of stem cell/differentiation markers. Mitochondrial biogenesis and structure was examined by transmission electron microscopy analysis. Bioinformatics analysis, qRT-PCR, glucose uptake assay and lactate production assays were applied to reveal metabolic difference. Results GSCs grown in serum culture conditions showed lower stem cell markers expression and higher differentiation markers compared to GSCs grown in stem cell culture conditions. In the serum culture conditions, biogenesis of mitochondria was significantly increased. RNA sequencing analysis using GSCs grown in stem cell culture or serum culture conditions revealed that differentiated GSCs are enriched with mitochondria-related gene signature. Also, glucose metabolism was increased in GSCs grown in stem cell culture conditions compared to serum culture conditions. Conclusions Under different culture conditions, GSCs show different mitochondrial biogenesis and cellular metabolism. Understanding mitochondria properties in cancer may lead us to discover a novel therapeutic target. Editorial acknowledgement Cancer Growth Regulation Laboratory for technical support and helpful advice. Legal entity responsible for the study The authors. Funding National Research Foundation of Korea (NRF) [grant numbers: 2015R1A5A1009024 and 2017R1E1A1A01074205], the School of Life Sciences and Biotechnology for BK21 Plus, Korea University and Institute of Animal Molecular Biotechnology, Korea University. Disclosure All authors have declared no conflicts of interest. [ABSTRACT FROM AUTHOR]