Performance evaluation of three automated quantitative immunoassays and their correlation with a surrogate virus neutralization test in coronavirus disease 19 patients and pre-pandemic controls.

BACKGROUND: SARS-CoV-2 pandemic is currently ongoing, meanwhile vaccinations are rapidly underway in some countries. The quantitative immunoassays detecting antibodies against spike antigen of SARS-CoV-2 have been developed based on the findings that they have a better correlation with the neutralizing antibody. METHODS: The performances of the Abbott Architect SARS-CoV-2 IgG II Quant, DiaSorin LIAISON SARS-CoV-2 TrimericS IgG, and Roche Elecsys anti-SARS-CoV-2 S were evaluated on 173 sera from 126 SARS-CoV-2 patients and 151 pre-pandemic sera. Their correlations with GenScript cPass SARS-CoV-2 Neutralization Antibody Detection Kit were also analyzed on 173 sera from 126 SARS-CoV-2 patients. RESULTS: Architect SARS-CoV-2 IgG II Quant and Elecsys anti-SARS-CoV-2 S showed the highest overall sensitivity (96.0%), followed by LIAISON SARS-CoV-2 TrimericS IgG (93.6%). The specificities of Elecsys anti-SARS-CoV-2 S and LIAISON SARS-CoV-2 TrimericS IgG were 100.0%, followed by Architect SARS-CoV-2 IgG II Quant (99.3%). Regarding the correlation with cPass neutralization antibody assay, LIAISON SARS-CoV-2 TrimericS IgG showed the best correlation (Spearman rho = 0.88), followed by Architect SARS-CoV-2 IgG II Quant and Elecsys anti-SARS-CoV-2 S (all rho = 0.87). CONCLUSIONS: The three automated quantitative immunoassays showed good diagnostic performance and strong correlations with neutralization antibodies. These assays will be useful in diagnostic assistance, evaluating the response to vaccination, and the assessment of herd immunity in the future.

Differential prognostic impact of CD8+ T cells based on human leucocyte antigen I and PD-L1 expression in microsatellite-unstable gastric cancer.

BACKGROUND: The aim of the study was to determine the human leucocyte antigen class-I (HLA-I), programmed death-ligand 1 (PD-L1) expression and tumour-infiltrating lymphocytes (TILs) of microsatellite instability-high gastric cancer. METHODS: The HLA-I expression type was determined by immunohistochemistry of HLA-A, HLA-B, HLA-C and ß2-microglobulin in the centre of the tumour (CT) and in the invasive margin (IM) of samples from 293 patients (total loss vs. preserved type). PD-L1 expression and TIL density was examined immunohistochemically. HLA-I genotyping was also performed. RESULTS: The expression loss of the HLA-I molecules was significantly associated with low TIL density. According to survival analyses, the HLA-I expression type and PD-L1 positivity were not independent prognostic factors. The TIL density had no prognostic implication when survival analysis was performed for the whole patient group; however, high CD8+ TIL infiltration was significantly associated with good prognosis in only HLA-I-preserved-type/PD-L1-positive group (p = 0.034). The homozygosity of the HLA-I allele was more frequently observed in the total loss type group. CONCLUSIONS: We confirmed differential prognostic implication of CD8+ TILs according to the HLA-I and PD-L1 expression. Determination of the HLA-I expression could be helpful to select patients who would benefit from anti-PD-1/PD-L1 therapy.

Is elevated microsatellite alterations at selected tetranucleotide repeats (EMAST)-negative/MSI-high colorectal cancer a distinct subtype of the disease?

BACKGROUND AND OBJECTIVES: Microsatellite instability (MSI) plays a prognostic and predictive role in colorectal cancer (CRC). Elevated microsatellite alterations at selected tetranucleotide repeats (EMAST), a novel type of MSI, was recently identified. METHODS: A retrospective analysis of a prospective cohort database was performed. Patients who attempted curative surgery for MSI-high (MSI-H) CRC and had available testing results of EMAST were included for analysis. The difference in clinical characteristics, immunohistochemistry profile, and 3-year recurrence-free and overall survival between EMAST-negative and EMAST-positive tumors was measured. RESULTS: EMAST status was successfully evaluated in 86 cases among patients who received EMAST testing, and only 16.3% (14/86) of these patients were EMAST-negative/MSI-H. Patients with EMAST-negative tumors were younger; their tumors exhibited well differentiation, less venous invasion, and greater mutS homolog 3 expression. There was no distant metastasis or cancer-specific death among EMAST-negative patients. Yet no statistically significant difference was found between the two groups in 3-year overall or recurrence-free survival. CONCLUSIONS: Patients with EMAST-negative/MSI-H CRC seem to have different clinicopathological characteristics. Future large-scale studies could clarify the role of EMAST genotype as a sub-classifier of MSI-H CRC.

Acceptable Donor-Specific Antibody Levels Before and After Desensitization Therapy in Living Donor Kidney Transplantation.

BACKGROUND: Plasmapheresis (PP) is commonly used for desensitization in highly sensitized patients with donor-specific antibodies (DSA) in living donor kidney transplantation. We analyzed the impact of DSA levels before and after desensitization on renal allograft outcome. METHODS: Twenty-three patients who underwent desensitization with PP, intravenous immunoglobulin (IVIG), and rituximab before kidney transplantation in Seoul National University Hospital from August 2006 to August 2016 were enrolled. The association of median fluorescent intensity (MFI) value of DSA with graft outcome was analyzed. RESULTS: The frequency of positive HLA class II DSA after desensitization was lower in patients without antibody-mediated rejection (AMR) compared to those with AMR (p = 0.006). The cutoff value of MFI sum of HLA class II DSA after desensitization for predicting AMR was 2,122 with 63% sensitivity and 94% specificity. The frequency of moderate HLA class II DSA (MFI 5,000 - 10,000) after desensitization was significantly higher in patients with graft loss compared to those without graft loss (p = 0.02). CONCLUSIONS: Weak HLA class II DSA after desensitization including PP, IVIG, and rituximab was related to AMR and moderate levels of HLA class II DSA after desensitization was related to graft loss in living donor kidney transplantation.

Recommendations Regarding Practical DEL Typing Strategies for Serologically D-Negative Asian Donors.

BACKGROUND: DEL, the weakest D variant, is mistyped as D-negative by routine serological assays. Transfusion of red blood cells expressing the DEL phenotype has the potential to elicit anti-D alloimmunization in D-negative recipients. The goal of this study was to recommend DEL typing strategies for serologically D-negative Asian donors. METHODS: RhCE phenotyping and the adsorption-elution test were performed on 674 serologically D-negative samples. RHD genotyping using real-time polymerase chain reaction and melting curve analysis were also undertaken to identify DEL alleles. Costs and turnaround time of RhCE phenotyping, the adsorption-elution test, and RHD genotyping were estimated. RESULTS: Sensitivity and specificity of the adsorption-elution test for serologically D-negative samples were 94.9% (93/98) and 91.5% (527/576), respectively. C+ phenotypes were detected in all 98 samples with DEL alleles. Despite comparable costs, RHD genotyping was more accurate and rapid than the adsorption-elution test. CONCLUSIONS: Two practical DEL typing strategies using RhCE phenotyping as an initial screening method were recommended for serologically D-negative Asian donors. Compared with DEL typing using RHD genotyping, serological DEL typing using adsorption-elution test is predicted to increase the incidence of anti-D alloimmunization and decrease the D-negative donor pool without having any cost-competitiveness but can be used in laboratories where molecular methods are not applicable.

Genotyping of 22 blood group antigen polymorphisms and establishing a national recipient registry in the Korean population.

It is often difficult for standard blood banks in Korea to supply adequate amounts of blood for patients with rare phenotype. Moreover, the definition of a blood in need is ambiguous, and much remains to be learned. In this study, we determined the prevalence of various red blood cell (RBC) antigens from a donor viewpoint and estimated the demand for specific antigen-negative blood from a patient viewpoint. Our data will aid the establishment of a Rare Blood Program in Korea (KRBP). RBC genotyping of 419 blood donors was performed using a Lifecodes RBC/RBC-R typing kit (Immucor, Norcross, GA). A national recipient registry website has been established. Each hospital-based blood bank voluntarily enters data on antibodies detected and identified and the outcomes of specific antigen testing. We calculated the availabilities of specific antigen-negative blood components based on these registry data and predicted the prevalence of RBC antigens via RBC genotyping. The prevalences of various RBC antigens in the D-negative population were determined for the first time, and the Cartwright, Scianna, Dombrock, Colton, Landsteiner-Wiener, Cromer, and Knops blood group systems were identified. The availabilities of specific antigen-negative units differed when calculations were based on serotyping or genotyping, especially in the D-negative group. Data on the prevalences of various blood antigens are essential for estimating the availabilities of blood components that are appropriate for use by patients expressing relevant antibodies. Then, blood banks would be able to efficiently supply safe blood products.

Development of Real-time PCR and Melting Curve Analysis for the Rapid Detection of DEL with RHD (c.1222T>C) or RHD (c.1227G>A).

BACKGROUND: DEL, a variant of RhD, is difficult to detect in routine blood bank testing owing to its extremely low levels of D antigen expression. However, DEL is capable of alloimmunizing a patient when transfused into RhDnegative individuals. METHODS: In this study, we developed real-time PCR and melting curve analysis for the rapid detection of the DEL phenotype. RESULTS: Of the 325 serologically RhD-negative individuals involved in the study, 56 (17.2%) had melting temperatures distinguishable from complete RHD absence as follows: 53 RHD (c.1227G>A) DEL specimens had a plateau at 54 - 56°C and a peak at 61.95°C, while 3 RHD (c.1222T>C) DEL had a melting temperature of 62.62°C. All DEL results were identical to those obtained by multiplex single-base primer extension reactions. CONCLUSIONS: The rapid DEL genotyping method developed in this study will be useful for screening DEL in serologically RhD-negative donors and preventing the alloimmunization of RhD-negative individuals by DEL.

Direct identification of Gram-positive bacteria and resistance determinants from blood cultures using a microarray-based nucleic acid assay: in-depth analysis of microarray data for undetermined results.

BACKGROUND: The Verigene Gram-Positive Blood Culture (BC-GP) nucleic acid assay (Nanosphere, Inc., Northbrook, IL, USA) is a newly developed microarray-based test with which 12 Gram-positive bacterial genes and three resistance determinants can be detected using blood culture broths. We evaluated the performance of this assay and investigated the signal characteristics of the microarray images. METHODS: At the evaluation stage, we tested 80 blood cultures that were positive for various bacteria (68 bacteria covered and 12 not covered by the BC-GP panel) collected from the blood of 36 patients and 44 spiked samples. In instances where the automated system failed and errors were called, we manually inspected microarray images, measured the signal intensities of target spots, and reclassified the results. RESULTS: With the manual analysis of the microarray images of 14 samples for which error calls were reported, we could obtain correct identification results for 12 samples without the need for retesting, because strong signals in the target spots were clearly discriminable from background noise. With our interpretation strategy, we could obtain 97.1% sensitivity and 100% specificity for bacterial identification by using the BC-GP assay. The two unidentified bacteria were viridans group streptococci, which produced weaker target signals. During the application stage, among 25 consecutive samples positive for Gram-positive bacteria, we identified two specimens with error calls as Streptococcus spp. by using manual analysis. CONCLUSIONS: With help of the manual review of the microarray images, the BC-GP assay could successfully identify species and resistance markers for many clinically important Gram-positive bacteria.

Comparison of xTAG respiratory virus panel and Verigene Respiratory Virus Plus for detecting influenza virus and respiratory syncytial virus.

BACKGROUND: Nucleic acid amplification tests have allowed simultaneous detection of multiple respiratory viruses. METHODS: We compared the results of a liquid bead array xTAG Respiratory Virus Panel (RVP; (Luminex Corporation, Toronto, Canada) and a solid microarray Verigene Respiratory Virus Plus (RV+; Nanosphere, Northbrook, IL) for the detection of influenza A virus (INF A), influenza B virus (INF B), and respiratory syncytial virus (RSV) in 170 respiratory specimens from hospitalized patients. RESULTS: Overall, xTAG RVP demonstrated sensitivities and specificities of 97.6 and 100% for INF A, 100 and 99.4% for INF B, and 100 and 100% for RSV, while the Verigene RV+ test sensitivities and specificities were 95.1 and 98.5%, 100.0 and 99.4%, and 97.1 and 100%, respectively. There were no significant differences in the area under the curves between the two assays for each virus (P = 0.364 for INF A, P = 1.000 for INF B, P = 0.317 for RSV). Comparing the results of two assays, discordant results were present mostly due to subtype assignments and identification of coinfections. The detection of viruses was not significantly different (P = 1.000) and the virus/subtype assignment showed good agreement with kappa coefficients of 0.908. CONCLUSION: The xTAG RVP and Verigene RV+ showed high sensitivities and specificities, and good overall agreement in detection and identification of INF and RSV. These assays can be used in clinical settings for a reliable detection of respiratory viruses found commonly in hospitalized patients.

Proposal of standardized guidelines for the production and quality control of autologous serum eye drops in Korea: based on a nationwide survey.

BACKGROUND: Autologous serum eye drops (ASEDs) have been used to treat many eye diseases. However, there are no standardized guidelines for the production and quality control (QC) of ASEDs in Korea. Our aim was to propose standardized guidelines for the production and QC of ASEDs. STUDY DESIGN AND METHODS: We conducted a nationwide survey consisting of questions regarding the methods used in each hospital for the production and QC of ASEDs. The survey was sent by e-mail to 89 doctors responsible for the blood banks at different hospitals. RESULTS: Thirty-two hospitals replied, and 13 hospitals reported using the ASEDs in the treatment of patients with eye diseases. The screening test for patients, amount of blood sampling, type of bottle used for blood collection, details about the production of the eye drops, and storage methods and shelf life of unopened and opened bottles of eye drops varied between hospitals. CONCLUSION: Based on an analysis of the survey results and a review of the standard operating procedures and protocols for ASEDs used in Japan, Germany, England and Wales, and the United States, we proposed standardized guidelines for the production and QC of ASEDs in Korea. ASEDs are not cell therapy products in the strictest sense. However, because eye drops are composed of serum isolated from blood and are used in patients, we consider ASEDs to be the basis for cell therapy products. Therefore, ASEDs should be produced and stored according to standardized guidelines based on the Good Manufacturing Practice guidelines.

Mobile calculator application for estimating human erythrocyte antigen frequency in Korea.

OBJECTIVES: This study aimed to establish a comprehensive human erythrocyte antigen (HEA) frequency data set for Koreans. It also sought to develop a mobile app that facilitates the calculation of the frequencies of specific antigen-negative red blood cell units and the average number of units required for antigen typing. METHODS: Human erythrocyte antigen frequencies were compiled from large-scale blood donor data and 5 previous papers. Based on the collected data, we developed a mobile calculator app for HEA frequency and evaluated its usability. RESULTS: Human erythrocyte antigen frequency data for 20 blood group systems, including the ABO, Rh, MNS, Duffy, Kidd, and Diego systems, were established. The app was designed to enable users to select the desired phenotype from a drop-down menu and display the calculated frequency at the bottom. The number of units required for antigen typing to find 1 compatible red blood cell unit was also displayed. Five users participated in app evaluation and rated the functionality and information categories highly. In quizzes prompting users to calculate frequencies using the app, all participants provided correct answers, confirming the app's user-friendly functionality. CONCLUSIONS: This app, which encompasses comprehensive HEA frequency data, is expected to find multiple uses in transfusion medicine, including optimizing blood bank workflow and defining rare blood groups in Korea.

A Korean family with RHD*DNT only detectable after anti-D alloimmunization.

OBJECTIVES: Identification of DNT, a rare partial D, can be challenging, as it is difficult to distinguish from D+. This study aimed to identify DNT individuals by analyzing the DNT proband's family members, characterize DNT, and propose management strategies. METHODS: Family members of the first Korean DNT proband were recruited. RHD genotyping was conducted, and weak D tests were carried out using several anti-D reagents. RESULTS: Three DNT individuals were identified among 6 family members, including 1 with an anti-D alloantibody. As DNT red cells exhibited strong reactivity with all anti-D clones, DNT was serologically indistinguishable from D+. Moreover, unusual serologic findings in DNT individuals only became apparent after anti-D alloimmunization. CONCLUSIONS: We recommend DNT individuals as candidates for Rh immune globulin prophylaxis during the perinatal period and transfusions with D- blood components. An anticipatory RHD genotyping is suggested for partial D family members to prevent potential partial D individuals from becoming alloimmunized.

Verification of a method using magnetic bead enrichment and nucleic acid extraction to improve the molecular detection of bacterial contamination in blood components.

Bacterial contamination of blood products poses a significant risk in transfusion medicine. Platelets are particularly vulnerable to bacterial growth because they must be stored at room temperature with constant agitation for >5 days. The limitations of bacterial detection using conventional methods, such as blood cultures and lateral flow assays, include the long detection times, low sensitivity, and the requirement for substantial volumes of blood components. To address these limitations, we assessed the performance of a bacterial enrichment technique using antibiotic-conjugated magnetic nanobeads (AcMNBs) and real-time PCR for the detection of bacterial contamination in plasma. AcMNBs successfully captured >80% of four bacterial strains, including Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Klebsiella pneumoniae, in both plasma and phosphate-buffered saline. After 24-h incubation with bacterial enrichment, S. aureus and B. cereus were each detected at 101 CFU/mL in all trials (5/5), E. coli at 101 CFU/mL in 1/5 trials, and K. pneumoniae at 10² CFU/mL in 4/5 trials. Additionally, without incubation, the improvement was also achieved in samples with bacterial enrichment, S. aureus at 10² CFU/mL and B. cereus at 101 CFU/mL in 1/5 trials each, E. coli at 10³ CFU/mL in 3/5 trials, and K. pneumoniae at 10¹ CFU/mL in 2/5 trials. Overall, the findings from this study strongly support the superiority of bacterial enrichment in detecting low-level bacterial contamination in plasma when employing AcMNBs and PCR.IMPORTANCEThe study presents a breakthrough approach to detect bacterial contamination in plasma, a critical concern in transfusion medicine. Traditional methods, such as blood cultures and lateral flow assays, are hampered by slow detection times, low sensitivity, and the need for large blood sample volumes. Our research introduces a novel technique using antibiotic-conjugated magnetic nanobeads combined with real-time PCR, enhancing the detection of bacteria in blood products, especially platelets. This method has shown exceptional efficiency in identifying even low levels of four different species of bacteria in plasma. The ability to detect bacterial contamination rapidly and accurately is vital for ensuring the safety of blood transfusions and can significantly reduce the risk of infections transmitted through blood products. This advancement is a pivotal step in improving patient outcomes and elevating the standards of care in transfusion medicine.

False-positive results of galactomannan assays in patients administered glucose-containing solutions.

Galactomannan (GM) is a polysaccharide cell wall component released by Aspergillus spp., and an immunoenzymatic GM assay is used for the diagnosis of invasive pulmonary aspergillosis. We evaluated the cause of strong positivity for GM in patients with no typical signs of aspergillosis. Repeat assays were performed using different instruments and reagent lots, but there were no differences in results among the assays. Patients with strongly positive GM results were investigated. Medication histories revealed that 14 of 23 patients had been administered total parenteral nutrition solution from one manufacturer and 4 patients had been administered dextrose solution from a different manufacturer before being tested. The results of GM assays conducted on samples of dextrose solution and the glucose fraction of the total parenteral nutrition solution were strongly positive, confirming the causes of the false-positive reactions. We hypothesize that a trace amount of GM was introduced into the glucose-containing solutions because glucoamylase, which is necessary for the saccharification step of glucose synthesis, was derived from Aspergillus niger. To enhance patient care and prevent unnecessary antifungal prescriptions, healthcare providers and manufacturers of healthcare products need to be aware of the possibility of false-positive reactions for GM.

Allele and haplotype frequencies of 11 HLA loci in Koreans by next-generation sequencing.

Data on HLA genotype distribution, including DQA1 and DPA1, in the Korean population are limited. We aimed to investigate the allele and haplotype frequencies of 11 HLA loci in 339 Korean subjects using next-generation sequencing (NGS)-based HLA typing. A total of 339 samples from unrelated healthy subjects were genotyped for HLA-A, -B, -C, -DRB1, -DRB3, -DRB4, -DRB5, -DQB1, -DQA1, -DPB1, and -DPA1 using two different NGS-based HLA typing kits (166 tested using the NGSgo-MX11-3 kit [GenDx, Netherlands] and 173 by the AllType NGS 11 Loci Amplification kit [One Lambda, USA]). PyPop software was used to estimate allele and haplotype frequencies and linkage disequilibrium between the loci. Additionally, a principal component analysis was performed to compare the allele distribution of Koreans with that of other populations. A total of 214 HLA alleles (97 class I and 117 class II alleles) were assigned. The most frequent alleles for each locus were A*24:02:01 (24.78%), B*15:01:01 (10.18%), C*01:02:01 (18.44%), DRB1*04:05:01 (9.59%), DRB3*02:02:01 (13.72%), DRB4*01:03:01 (25.81%), DRB5*01:01:01 (9.0%), DQA1*01:02:01 (16.96%), DQB1*03:01:01 (14.31%), DPA1*01:03:01 (44.4%), and DPB1*05:01:01 (35.1%), respectively. The most frequent haplotypes were A*33:03:01-C*03:02:02-B*58:01:01 for HLA class I (5.01%) and DRB1*04:05:01-DQA1*03:03:01-DQB1*04:01:01-DPA1*02:02:02-DPB1*05:01:01 for HLA class II (6.23%). The total allelic ambiguities by NGS were estimated to be minimal and considerably decreased compared with those by Sanger sequencing. The Japanese population had the most similar allele distribution to Koreans, followed by the Chinese population. Frequency data of 11 HLA loci in Koreans can provide essential data for population genetics and disease association studies.

A voluntary transfusion recipient registry in Korea as a database for blood group antibodies.

BACKGROUND: Several types of transfusion-related registries have been developed to improve patient outcomes and blood banks. In Korea, a transfusion program functioning as a blood group antibody database and a reference laboratory has been in operation since July 2013. This study was conducted to determine the current status of blood group antigens and antibodies in Korea and propose a model for registries in the field of transfusion medicine. MATERIALS AND METHODS: Cases with unexpected red cell antibodies were registered online in the voluntary transfusion registry. Specific antigen-negative frequencies were calculated based on the recorded data. To determine the frequencies of RhCE antigens, data added via the Blood Information Sharing System were also analyzed. Data added to the registries between July 2013 and June 2022 were included in the analysis. RESULTS: Among 9,048 antibody cases registered from 29 hospitals, anti-E alone was identified most commonly, followed by anti-E and c, anti-C and e, anti-Lea, and anti-M (2,202, 1,792, 757, 618, and 383 cases, respectively). The frequencies of E-, E-c-, C-e-, Le(a-), and M- were 49.1%, 41.6%, 9.1%, 69.4%, and 21.8%, respectively. DISCUSSION: The distributions of antibodies and antigen frequencies were estimated through the transfusion registry. Antigen frequencies were calculated based on the results of antigen typing of red blood cell components performed at the time of issuing. The online transfusion registry serving as a blood group antibody database is useful for determining the frequencies of blood group antigens and antibodies.

Prediction of various blood group systems using Korean whole-genome sequencing data.

AIMS: This study established blood group analysis methods using whole-genome sequencing (WGS) data and conducted blood group analyses to determine the domestic allele frequency using public data from the Korean whole sequence analysis of the Korean Reference Genome Project conducted by the Korea Disease Control and Prevention Agency (KDCA). MATERIALS AND METHODS: We analyzed the differences between the human reference sequences (hg19) and the conventional reference cDNA sequences of blood group genes using the Clustal Omega website, and established blood group analysis methods using WGS data for 41 genes, including 39 blood group genes involved in 36 blood group antigens, as well as the GATA1 and KLF1 genes, which are erythrocyte-specific transcription factor genes. Using CLC genomics Workbench 11.0 (Qiagen, Aarhus, Denmark), variant analysis was performed on these 41 genes in 250 Korean WGS data sets, and each blood group's genotype was predicted. The frequencies for major alleles were also investigated and compared with data from the Korean rare blood program (KRBP) and the Erythrogene database (East Asian and all races). RESULTS: Among the 41 blood group-related genes, hg19 showed variants in the following genes compared to the conventional reference cDNA: GYPA, RHD, RHCE, FUT3, ACKR1, SLC14A1, ART4, CR1, and GCNT2. Among 250 WGS data sets from the Korean Reference Genome Project, 70.6 variants were analyzed in 205 samples; 45 data samples were excluded due to having no variants. In particular, the FUT3, GNCT2, B3GALNT1, CR1, and ACHE genes contained numerous variants, with averages of 21.1, 13.9, 13.4, 9.6, and 7.0, respectively. Except for some blood groups, such as ABO and Lewis, for which it was difficult to predict the alleles using only WGS data, most alleles were successfully predicted in most blood groups. A comparison of allele frequencies showed no significant differences compared to the KRBP data, but there were differences compared to the Erythrogene data for the Lutheran, Kell, Duffy, Yt, Scianna, Landsteiner-Wiener, and Cromer blood group systems. Numerous minor blood group systems that were not available in the KRBP data were also included in this study. CONCLUSIONS: We successfully established and performed blood group analysis using Korean public WGS data. It is expected that blood group analysis using WGS data will be performed more frequently in the future and will contribute to domestic data on blood group allele frequency and eventually the supply of safe blood products.

Molecular detection of bacterial contamination in plasma using magnetic-based enrichment.

Bacterial contamination of blood products is a major problem in transfusion medicine, in terms of both morbidity and mortality. Platelets (PLTs) are stored at room temperature (under constant agitation) for more than 5 days, and bacteria can thus grow significantly from a low level to high titers. However, conventional methods like blood culture and lateral flow assay have disadvantages such as long detection time, low sensitivity, and the need for a large volume of blood components. We used real-time polymerase chain reaction (PCR) assays with antibiotic-conjugated magnetic nanobeads (MNBs) to detect enriched Gram-positive and -negative bacteria. The MNBs were coated with polyethylene glycol (PEG) to prevent aggregation by blood components. Over 80% of all bacteria were captured by the MNBs, and the levels of detection were 101 colony forming unit [CFU]/mL and 102 CFU/mL for Gram-positive and -negative bacteria, respectively. The detection time is < 3 h using only small volumes of blood components. Thus, compared to conventional methods, real-time PCR using MNBs allows for rapid detection with high sensitivity using only a small volume of blood components.

Usefulness of three-channel multiplex real-time PCR and melting curve analysis for simultaneous detection and identification of the Mycobacterium tuberculosis complex and nontuberculous mycobacteria.

We attempted to determine the benefits of three-channel multiplex real-time PCR and melting curve analysis not only in detecting and distinguishing between nontuberculous mycobacteria (NTM) and the Mycobacterium tuberculosis complex but also in identifying NTM to the species level.