Comprehensive assessment of SARS-CoV-2 antibodies against various antigenic epitopes after naive COVID-19 infection and vaccination (BNT162b2 or ChAdOx1 nCoV-19).

Comprehensive assessment of SARS-CoV-2 antibodies against antigenic epitopes and cross-neutralization on variants is essential to monitor after infection or vaccination. From 32 COVID-19 patients and 40 vaccinated individuals [20 Oxford-AstraZeneca (AZ) and 20 Pfizer-BioNTech (BNT)], 348 serial sera are collected until 40 days after infection and 3 months after homologous booster vaccination. Antibody levels were monitored using a multiplex-bead assay including variant spike antigens, Roche (S1/RBD total) and a surrogate virus neutralization test (GenScript). Anti-S/S1/RBD levels were higher than anti-S2/N levels from 2 weeks after infection and were higher in severe infection (P < 0.05). Vaccination showed highest antibody levels after 1-month booster and had consistently high levels in the order of anti-full S, anti-RBD, anti-S1 and anti-S2. Infection induced higher anti-S2/N levels than prime vaccination (P < 0.05). Three months after BNT/BNT vaccination, antibody levels against S1/RBD and 23 variant antigens were higher than post-infection or AZ groups (P < 0.05). Regarding intraindividual changes from post-prime to post-boost vaccination, boost induced a 1.1- to 3.9-fold increase on multiplex-bead assay, 22.8- to 24.2-fold on Roche assay and 22.8- to 24.2-fold on GenScript assay. Post-prime levels by multiplex-bead assay predicted post-boost levels, but Roche and GenScript results were not predictive in the AZ group. The kinetics of SARS-CoV-2 antibody levels vary depending on the antigenic epitopes, assay kit, disease severity or vaccine type. Assessing seroconversion using multiplex-bead assays may contribute to monitoring the disease course, adjusting vaccination strategies, and accelerating vaccination efficacy.

Identification of propagated defects to reduce software testing cost via mutation testing.

In software engineering, testing has long been a research area of software maintenance. Testing is extremely expensive, and there is no guarantee that all defects will be found within a single round of testing. Therefore, fixing defects that are not discovered by a single round of testing is important for reducing the test costs. During the software maintenance process, testing is conducted within the scope of a set of test cases called a test suite. Mutation testing is a method that uses mutants to evaluate whether the test cases of the test suite are appropriate. In this paper, an approach is proposed that uses the mutants of a mutation test to identify defects that are not discovered through a single round of testing. The proposed method simultaneously applies two or more mutants to a single program to define and record the relationships between different lines of code. In turn, these relationships are examined using the defects that were discovered by a single round of testing, and possible defects are recommended from among the recorded candidates. To evaluate the proposed method, a comparative study was conducted using the fault localization method, which is commonly employed in defect prediction, as well as the Defects4J defect prediction dataset, which is widely used in software defect prediction. The results of the evaluation showed that the proposed method achieves a better performance than seven other fault localization methods (Tarantula, Ochiai, Opt2, Barinel, Dstar2, Muse, and Jaccard).

Assessment of silibinin as a potential antifungal agent and investigation of its mechanism of action.

Silibinin, which is derived from Silybum marianum (milk thistle), has used as a traditional remedy for liver or biliary disorders and known to have superior antioxidant activity. In addition, silibinin was recently reported to have antifungal effect related to fungal apoptosis against Candida albicans and the interest in the therapeutic effect is increasing. In this study, we found another mode of antifungal action of silibinin and its antibiofilm activity on C. albicans. To investigate influence on fungal plasma membrane, propidium iodide and bis-(1, 3-dibutylbarbituric acid) trimethineoxonol [DiBAC4 (3)] assay were primarily carried out. After 5-h incubation with silibinin (50, 100, 150, or 200 µg/mL), the propidium iodide fluorescent percentages increased by 11.90%, 28.50%, 34.10%, and 44.52%, respectively, and the DiBAC4 (3) fluorescent percentages increased by 13.18%, 34.64%, 46.99%, and 57.15%, respectively. As a result, we thought that silibinin concentrations of more than 100 µg/mL have a membrane-damaging effect. Subsequently, to estimate the degree of membrane damage, we used Fluorescein isothiocyanate-labelled dextrans (FDs) of various sizes and the results indicated that silibinin allowed penetration of molecules smaller than approximately FD20 (3.3 nm). In addition, silibinin inhibited the dimorphic transition of C. albicans and resulted in the inhibition of biofilm development at an early stage. In conclusion, we found membrane-damaging effect of silibinin and its antibiofilm effect in C. albicans. © 2017 IUBMB Life, 69(8):631-637, 2017.

Cost-benefit Analysis of Posaconazole Versus Fluconazole or Itraconazole as a Primary Antifungal Prophylaxis in High-risk Hematologic Patients: A Propensity Score-matched Analysis.

PURPOSE: Posaconazole is effective for the prophylaxis of invasive fungal infections (IFIs) in patients with acute myeloid leukemia or myelodysplastic syndrome during remission induction chemotherapy. However, a cost-benefit analysis of posaconazole versus fluconazole or itraconazole has not been conducted in Korea. METHODS: We retrospectively reviewed data for all consecutive patients who received primary antifungal prophylaxis during remission induction chemotherapy in our acute myeloid leukemia/myelodysplastic syndrome cohort from December 2010 to November 2013. Patient characteristics and factors known as a risk of IFI were matched with propensity score analysis. We evaluated the medical cost according to the prophylactic antifungal agents (posaconazole vs fluconazole/itraconazole), the development of breakthrough IFIs, and survival status after propensity score matching in a 1:1 ratio. FINDINGS: Of the 419 baseline patients, 100 patients in each group were analyzed after matching. A significant decrease was found in the development of breakthrough proven or probable IFIs (3.0% vs 14.0%; P = 0.009) and the rate of empirical antifungal therapy (EAFT) (12.0% vs 46.0%; P < 0.001) in the posaconazole group. Total in-hospital medical costs per patient were not statistically different between posaconazole and fluconazole/itraconazole prophylaxis. However, the daily medical cost was lower for posaconazole prophylaxis, resulting in a total daily cost savings of $72 (₩79,458) per patient (P = 0.002). In the cases of breakthrough proven/probable IFIs, EAFT, and in-hospital deaths, the total medical costs per patient were significantly higher than in nonproven/probable IFIs, non-EAFT, and in-hospital survivors, as much as $7,916 (₩8,700,758), $4605 (₩5,062,529), and $11,134 (₩12,238,422), respectively. Costs for the antifungal agent used in targeted or empirical therapy were lower in the posaconazole group, resulting in a savings of $697 (₩766,347) per patient (P < 0.001). IMPLICATIONS: Posaconazole appears to be cost beneficial for primary antifungal prophylaxis in high-risk patients with hematologic malignancy, at a single center, in Korea. Cost-benefit is closely related with clinical outcomes, including breakthrough IFI development, EAFT, and survival status.

Risk-adapted preemptive therapy for cytomegalovirus disease after allogeneic stem cell transplantation: a single-center experience in Korea.

Cytomegalovirus (CMV) remains a major cause of infection in recipients of hematopoietic stem cell transplants (HSCT) and results in significant mortality and morbidity. We present the results of CMV pp65 antigenemia-guided, risk-adapted preemptive therapy aimed at preventing CMV disease in allogeneic HSCT. Preemptive ganciclovir treatment was started when more than 5 CMV antigen-positive cells were detected in the low-risk group (with grade 0-I acute GVHD and matched related HSCT) and when any antigen-positive cells were seen in the high-risk group (with grade II-IV acute GVHD or matched unrelated HSCT). At least 1 episode of antigenemia was observed in 53 (59.6%) of 89 patients before day 100, and preemptive therapy was performed in 33 patients. CMV disease occurred in 6 patients (5 in the high-risk group and 1 in the low-risk group), and late CMV disease developed in 4 patients. Only 1 patient died of CMV pneumonitis before day 100. Neutropenia was observed in 51.5% of ganciclovir-treated patients, and coinfection/superinfection was observed in 42.4%. A strategy of ganciclovir treatment focusing on patients at higher risk could reduce the toxicity from the antiviral drug and be cost-effective. Extended surveillance for CMV disease using more sensitive diagnostic methods is necessary in high-risk patients.