Reactive Samples Research Articles

High-Throughput Adaptable SARS-CoV-2 Screening for Rapid Identification of Dominant and Emerging Regional Variants.

ObjectivesEmerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant strains can be associated with increased transmissibility, more severe disease, and reduced effectiveness of treatments. To improve the availability of regional variant surveillance, we describe a variant genotyping system that is rapid, accurate, adaptable, and able to detect new low-level variants built with existing hospital infrastructure.MethodsWe used a tiered high-throughput SARS-CoV-2 screening program to characterize variants in a supraregional health system over 76 days. Combining targeted reverse transcription–polymerase chain reaction (RT-PCR) and selective sequencing, we screened SARS-CoV-2 reactive samples from all hospitals within our health care system for genotyping dominant and emerging variants.ResultsThe median turnaround for genotyping was 2 days using the high-throughput RT-PCR–based screen, allowing us to rapidly characterize the emerging Delta variant. In our population, the Delta variant is associated with a lower cycle threshold value, lower age at infection, and increased vaccine-breakthrough cases. Detection of low-level and potentially emerging variants highlights the utility of a tiered approach.ConclusionsThese findings underscore the need for fast, low-cost, high-throughput monitoring of regional viral sequences as the pandemic unfolds and the emergence of SARS-CoV-2 variants increases. Combining RT-PCR–based screening with selective sequencing allows for rapid genotyping of variants and dynamic system improvement.

Investigation on HTLV Infection among Voluntary Blood Donors in Wuzhou City

Objective: To understand the infection of HTLV among voluntary blood donors in Wuzhou City, and to provide reference for the national health administrative department to formulate blood safety screening strategies. Methods: The HTLV double-antigen sandwich ELISA reagent was used to screen the blood samples of unpaid blood donors, and the reactive samples in the initial screening were subjected to a double-well retest; Specimens that were still reactive in the retest were further confirmed by viral nucleic acid amplification test (PCR) and western blotting (WB). Results: A total of 9 of 20,222 unpaid blood donation samples were screened to be reactive, and the screening response rate was 0.04%; Two samples of HTLV-1 nucleic acid and western blotting (WB) were confirmed to be positive, and the other seven samples were negative; The confirmed positive rate was 0.01%. Conclusion: There was a certain positive rate of HTLV-1 serological screening among the non remunerated blood donors in Wuzhou City, and the confirmation test confirmed that there was a certain risk of HTLV infection; In order to further understand the HTLV infection of blood donors in this city, we should further increase the number of screening samples, so as to obtain more reliable and accurate data in this region, and provide data and reference for the health administration department to formulate HTLV screening strategies for blood donors.

Seroprevalence of anti-severe acute respiratory syndrome coronavirus 2 antibody among healthy blood donors in a hospital-based blood center in Eastern India during the COVID-19 pandemic.

BACKGROUND:Few international studies have reported the prevalence of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in healthy, asymptomatic blood donors. These findings have definitely raised queries regarding blood safety and transfusion-transmitted coronavirus disease (COVID)-19. We conducted this first anti-SARS-CoV-2 seroprevalence survey among the healthy blood donors in Eastern India.MATERIALS AND METHODS:The study included 611 healthy blood donors who donated whole blood (WB) in our blood center. For detailed analysis, social and demographic details of all donors like gender, age, weight, occupation, and place of residence were included. Donor eligibility criteria for WB donation were followed as per existing national guidelines. Residual serum samples leftover after screening the mandatory infectious markers were tested for the presence of anti-SARS-CoV-2 IgG directed against domain S1 and S2 of the SARS-CoV-2 spike protein using automated enhanced chemiluminescence technology following the manufacturer's instructions.RESULTS:The mean overall seroprevalence of anti-SARS-CoV-2 antibody in blood donors was observed to be 4.4% (95% confidence interval 3.8–4.9) with a monthly increasing trend. Seroprevalence adjusted for sensitivity and specificity of the assay was 4.1%. The mean S/Co values of reactive donor samples were observed to be 2.99 and 3.42 in June and July 2020, respectively (P = 0.013). No significant variation in seroprevalence rate was observed among donor variables like donor age, gender, profession, and educational qualification. A higher significant prevalence of antibody was observed among voluntary donors and donors residing in suburban areas (P < 0.05). Among the ABO blood groups, no statistical significance of seroprevalences was observed among the various ABO blood groups.CONCLUSION:We conclude that despite many limitations in the current study, we found 4.4% seroprevalence of anti-SARS-CoV-2 antibody in the asymptomatic, healthy, epidemiologically, and medically screened blood donors. These data are definitely the tip of an iceberg and signify much higher seroprevalence in the normal population and indicate that protective measures like masking and social distancing should remain implemented for a long term.

Prevalence of Cytomegalovirus, Rubella and Toxoplasma gondii among Internally Displaced Women of District North Waziristan, Pakistan with Home Obstetric History

The present study was conducted to estimate the prevalence rate and to identify risk factors of Cytomegalovirus, Rubella and Toxoplasma gondii among internally displaced women of District North Waziristan, Pakistan with home obstetric history. A total of 387 blood samples were collected from internally displaced infected women with the help of a comprehensive filled data form. To determine levels of Cytomegalovirus, Rubella and Toxoplasma gondii Infection, all blood samples were qualitative and quantitative analyzed using Immune chromatographic and Chemiluminescence Microparticle Immunoassay (CMIA) technique. Among 387 blood samples, the total numbers of reactive samples observed were 341 (88.11%) and non-reactive samples were 46 (11.88%). Of 341 (88.11%) reactive samples, the highest ratio 168 (49.26%) was reported for the co-infection of Cytomegalovirus and Rubella, followed by 76 (22.28%) for Cytomegalovirus, Rubella and Toxoplasma gondii combined. In reactive samples, the highest ratio of IgG was noted in order of CMV 22 (64.70%), Rubella 21 (67.74%) and Toxoplasma gondii 16 (72.72%), followed by IgG+IgM and IgM only. Regarding age-wise distribution, the highest ratio 144 (90.56%) of total reactive samples of Cytomegalovirus, Rubella and Toxoplasma gondii was reported in the 25-32 years old group of individuals. Similarly, the highest ratio 53 (48.18%) and 60 (41.66%) of co-infection among reactive samples for Cytomegalovirus, and Rubella was observed in 18-24 and 25-32 years old group. Further, the highest ratio of 100 (40.32%) of risk factors was observed in infected patients who were exposed to a poor hygienic environment and 57 (44.18%) of infected patients had complications of Severe UTI followed by others. Hence, it was revealed that Cytomegalovirus, Rubella and Toxoplasma gondii infection was most prevalent in internally displaced women of District North Waziristan, Pakistan. Therefore, an urgent base prophylactic approaches should need to be addressed to reduce the risk of the spread of disease in this locality.

Use of flow cytometry and cytology to differentiate breast implant-associated anaplastic large cell lymphoma from reactive seromas in Brazilian patients.

The combination of cytology and multiparametric flow cytometry (MFC) may be useful in the diagnosis of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) and may be a practical way to differentiate lymphoma from benign and reactive seromas. Although the Brazilian breast implant market is the second largest in the world, with several manufacturers and the almost exclusive use of textured implants, the occurrence of BIA-ALCL in Brazil is underreported. One hundred seventeen sequential collections of suspicious periprosthetic fluid (PF) from 105 Brazilian patients registered between March/2018 and March/2021 were evaluated by routine cytomorphology and flow cytometry. The combination of CD30, HLA-DR, and CD25 was used together with T and B lymphocyte and monocyte evaluation. The PF samples were divided into positive, acute reactive (neutrophilic exudate), or chronic reactive (macrophage or lymphocyte rich), and unavailable samples. Nine BIA-ALCL positive cases (7.7%) were identified, with typical morphology and increased FSC/SSC dispersion, bright expression of CD30, CD25 and HLA-DR, and absence or weakness of T-cell antigens (CD3, CD8, CD4, CD5, and CD7). Reactive samples were acute (n= 18, 15.4%) and chronic (n= 70, 59.8%). Twenty samples were excluded. The mean age of BIA-ALCL patients was 50 years (31-57 years) and 35 years in reactive patients (20-69 years). Use of MFC with a comprehensive antibody panel consisting of CD30 in conjunction with CD25 and HLA-DR can discriminate anaplastic cells of BIA-ALCL from lymphoid or neutrophilic reactive cells and should be considered in the initial evaluation of seroma.

Effect on Current Density on Zero Charge Corrosion Protection of Pure Mg in 3.5% NaCl Solution

The cathodic protection uses two-electrode polarization, which requires large currents and substantial voltages. Efforts are being made to identify possibilities for improvements by developing zero-charge corrosion protection techniques. Studies were performed to determine the zero-charges potential effect by analyzing corrosion signs on reactive metal samples such as pure Mg. Mg samples were fed by current/ voltage pulses for 120 hours, with specified pulse parameters and varied Ecorr- offsets, ranging from +2 to -218 mV. The volumetric hydrogen gas collection technique is used to determine the hydrogen evolution rate. Surface observation is carried out by stereomicroscope to determine the presence of corrosion signs on the sample surface. Overall, all current densities and hydrogen evolution rates had very low readings on the studied Ecor offset parameters. Mg samples fed with pulses at -1800 and -1900 mV vs SCE revealed zero charge potential effects since their surface was clean and showed no indications of corrosion even after being exposed to the corrosive solution for 120 hours. Thus, corrosion protection is successfully done and meets the Epzc condition.

Oxygen-free transport of samples in silane-doped inert gas atmospheres for surface analysis

We report on a new approach to transport samples for surface analysis safely from oxidation over long distances. The transport method is based on silane-doped inert gases, which are used as a transport medium. In this paper, we show that with the help of silane, highly purified inert gas atmospheres with oxygen contents of less than 10−15 mbar can be generated. In addition, we demonstrate that compared to commercially available inert gases, silane-doped inert gas atmospheres can be efficiently used to store and transport samples safely from oxidation. For this, surface sensitive measurements on highly reactive titanium samples, which passed the different stages of samples transport, were performed. The measurements revealed that no pronounced oxidation by the silane-doped atmosphere takes place. However, adsorption of silicon oxide from the atmosphere was observed.

Anti-TRBC1 Antibody-Based Flow Cytometric Detection of T-Cell Clonality: Standardization of Sample Preparation and Diagnostic Implementation.

Simple SummaryThe anti-TRBC1 antibody JOVI-1 has recently been identified as a flow cytometry marker potentially useful for assessment of T-cell clonality. The aim of this study was to optimize a flow cytometric method for routine use of anti-TRBC1 to assess T-cell clonality and validate it in a large series of normal and pathological samples. Our results showed that the best resolution to accurately identify TRBC1+ cells was achieved by adding the CD3 antibody either simultaneously or after TRBC1. In addition, TRBC1+/TRBC1− ratios within different Tαβ-cell subsets are provided as expected reference ranges for polyclonal T-cells. Based on the optimized approach here proposed, we detected monoclonal Tαβ-cell populations with high specificity (96%) and a high analytical sensitivity/level of detection (≤10−4), when clonal T-cells exhibited immunophenotypic aberrancies. These findings further support and extend previous observations about the utility of TRBC1 for the diagnostic screening and monitoring of clonal Tαβ-cell populations.A single antibody (anti-TRBC1; JOVI-1 antibody clone) against one of the two mutually exclusive T-cell receptor β-chain constant domains was identified as a potentially useful flow-cytometry (FCM) marker to assess Tαβ-cell clonality. We optimized the TRBC1-FCM approach for detecting clonal Tαβ-cells and validated the method in 211 normal, reactive and pathological samples. TRBC1 labeling significantly improved in the presence of CD3. Purified TRBC1+ and TRBC1− monoclonal and polyclonal Tαβ-cells rearranged TRBJ1 in 44/47 (94%) and TRBJ1+TRBJ2 in 48 of 48 (100%) populations, respectively, which confirmed the high specificity of this assay. Additionally, TRBC1+/TRBC1− ratios within different Tαβ-cell subsets are provided as reference for polyclonal cells, among which a bimodal pattern of TRBC1-expression profile was found for all TCRVβ families, whereas highly-variable TRBC1+/TRBC1− ratios were observed in more mature vs. naïve Tαβ-cell subsets (vs. total T-cells). In 112/117 (96%) samples containing clonal Tαβ-cells in which the approach was validated, monotypic expression of TRBC1 was confirmed. Dilutional experiments showed a level of detection for detecting clonal Tαβ-cells of ≤10−4 in seven out of eight pathological samples. These results support implementation of the optimized TRBC1-FCM approach as a fast, specific and accurate method for assessing T-cell clonality in diagnostic-FCM panels, and for minimal (residual) disease detection in mature Tαβ+ leukemia/lymphoma patients.

Characterization of linear epitope specificity of antibodies potentially contributing to spontaneous clearance of hepatitis C virus.

Around 30% of the HCV infected patients can spontaneously clear the virus. Cumulative evidence suggests the role of neutralizing antibodies in such spontaneous resolution. Understanding the epitope specificity of such antibodies will inform the rational vaccine design as such information is limited to date. In addition to conformational epitope targeted antibodies, linear epitope specific antibodies have been identified that are broadly cross reactive against diverse HCV strains. In this study, we have characterized the potential role of three conserved linear epitopes in the spontaneous clearance of HCV. We tested the reactivity of sera from chronic patients (CP) and spontaneous resolvers (SR) with linear peptides corresponding to three conserved regions of HCV envelope protein E2 spanning amino acids 412-423, 523-532 and 432-443 using ELISA. Subsequently, we characterized the dependency of HCV neutralization by the reactive serum samples on the antibodies specific for these epitopes using pseudoparticle-based neutralization assay. In ELISA most of the CP sera showed reactivity to multiple peptides while most of the SR samples were reactive to a single peptide suggesting presence of more specific antibodies in the SR sera. In most of the HCVpp neutralizing sera of particular peptide reactivity the neutralization was significantly affected by the presence of respective peptide. HCV neutralization by CP sera was affected by multiple peptides while 75% of the HCVpp neutralizing SR sera were competed by the 432 epitope. These findings suggest that individuals who spontaneously resolve HCV infection at the acute phase, can produce antibodies specific for conserved linear epitopes, and those antibodies can potentially play a role in the spontaneous viral clearance. The epitope present in the 432-443 region of E2 was identified as the primary neutralizing epitope with potential role in spontaneous viral clearance and this epitope potentiates for the design of immunogen for prophylactic vaccine.

Multiple Sexual Partners as Major Predictor of Human Immunodeficiency Virus Seropositivity Among Pregnant Women, Osun State, Nigeria.

Concerning human immunodeficiency virus (HIV) epidemiology, pregnant women (PW) are particularly vulnerable and severely affected. Nigeria has over 40 years of HIV epidemiology and enlightenments; to suggest control hub, we sought to know extant variables predicting HIV positivity among PW in selected towns in Osun State. Our hypothesis: none of the study PW's variables predicts HIV seropositivity. With ethics approval from UNIOSUN Health Research Ethics Committee, 900 consecutively selected consenting PW attending antenatal care (ANC) facilities in four towns (capital city inclusive) provided relevant sociodemographic/behavioral data with questionnaire forms; each participant was aseptically bled and plasma screened with the Alere Determine® Rapid HIV-1/2 Kit. The presumptive reactive plasma samples (and some randomly selected nonreactive samples) were confirmed with Genscreen® ULTRA HIV-1/2 P24 antigen/antibody ELISA. Microsoft Excel and SPSS 16.0 were used for result analysis using t-test, CHI2 test, and binary logistic regression. The PW were 15-50 years of age (n = 900; mean: 26.6 years [95% CI: 26.1-26.9 years]); they were predominantly 15-29 years (71.1%), married (90.8%), with one lifetime sexual partner (86.4%). Seropositive PW by screening and confirmatory tests were, respectively, 14 (1.6% [95% CI: 0.9-2.6%]) and 15 (1.7% [95% CI: 0.9-2.7%]). The latter were predominantly 20-30 years (80.0%), married (93.3%), with ≤ secondary school education (86.7%), reportedly never screened for HIV (60.0%), with 86.7% aware HIV is sexually transmitted. Analysis showed only ≥ three lifetime sexual partners was independently associated with HIV seropositivity (p = 0.03; odds ratio (OR) = 17.0). Although educational status was not associated with seropositivity, PW having primary school education had about 6 times higher likelihood of seropositivity (p = 0.06; OR = 5.7 [95% CI: 0.94-35.1]). Also, primigravida had about twice higher likelihood of seropositivity (p = 0.44; OR = 1.5 [95% CI: 0.54-4.17]). HIV seropositivity was relatively low and majorly predicted by ≥ three lifetime sexual partners; suggesting this as prime focus of HIV counseling among PW attending ANC in Osun State, Nigeria.

Real-World Clinical Performance Evaluation of a Fourth-Generation HIV Antigen/Antibody Differentiation Test.

HIV testing is still an important component of routine sexual health screening, assessment of at-risk individuals and as part of the care of pregnant women. To prevent further transmission of infection, it is important that HIV tests are highly sensitive and that positive cases are not missed. HIV serologic antigen/antibody tests are commonly used as they are capable of detecting recent and established infection. In this study we assessed the performance of the Elecsys HIV Duo assay (Elecsys assay) against the Abbott Architect assay in 10 121 samples from US and non-US adult, pediatric, and pregnant populations including low-risk, high-risk, and known positive cohorts. Congruent repeatedly reactive and/or discrepant samples followed a confirmatory algorithm consisting of an antigen/antibody differentiation assay and a nucleic acid test, as per the study protocol. The overall sensitivity of the Elecsys assay was 100.00% (95% CI 99.81-100.00 [1977/1977]), and the specificity was 99.84% (95% CI 99.73-99.91 [8129/8142]). The Elecsys assay detected all positive samples within the study, including all 50 antigen-only positive samples and samples from different HIV subtypes, including group O, group M subtypes, HIV-2 positives, and HIV-1 and HIV-2 dual positives. The Elecsys HIV Duo assay was highly sensitive for diagnosis of HIV in a range of clinical samples from the United States and outside the United States and is suitable for routine use.

English

BACKGROUND Blood transfusion is a common life-saving medical procedure, but it may cause acute and delayed complications. A transfusion transmissible infection (TTI) is any infection that is transmissible from person-to-person through parenteral administration of blood or blood products i.e. packed red blood cells (RBC), platelets, plasma and other blood products. This study was undertaken to assess the prevalence of transfusion transmissible infections among blood donors in blood bank connected to a tertiary care hospital in Kerala and evaluate the safety of the blood donations. METHODS Samples of 13,262 donors from January to June 2018 were taken. All the donors who were accepted for donation as per criteria by national acquired immunodeficiency syndrome (AIDS) control society were included in the study. Consent was obtained from blood donors to conduct testing for transfusion transmitted diseases. Donors were screened by 4th generation enzyme linked immuno sorbent assay (ELISA) test kits for HIV-1/2, 3rd generation ELISA test kits for HBsAg and hepatitis C virus (HCV), rapid immunochromatographic test for malaria and rapid plasma reagin (RPR) test for syphilis. Tests were performed as per manufacturer instructions. All the reactive samples were discarded as per the guidelines. RESULTS Among 13,262 donors, 13,014 (98.12 %) were males and 248 (1.8%) were females within the age group of 18 - 60 years. Out of these, 7 (0.052%) donors were HBsAg positive and 3 (0.02%) were HIV positive. RPR reactivity was seen in 2 donors (0.01%) only. None of the blood donors tested showed positivity for HCV or malarial parasite. In this study, prevalence of hepatitis B was highest (0.052) followed by HIV (0.02%) and syphilis (0.02%). CONCLUSIONS Hepatitis B virus (HBV) is the most common transfusion transmissible infection among apparently healthy donors, followed by HIV and syphilis. TTI’s can be eliminated or reduced by implementing an integrated strategy for blood safety, like effective selection of blood donors, avoiding unnecessary transfusions, and early detection of TTIs. KEYWORDS Transfusion-Transmitted Infections, HIV, HBV, HCV

Prostaglandin EP4 receptor mRNA expression in canine lymphoma.

Canine lymphoma (LSA) is a diverse, aggressive malignancy initiated by a variety of factors. Understanding those factors could help identify potential treatment options. Chronic inflammation drives lymphoma in human medicine and is suspected to play a role in veterinary medicine. The exact mechanisms, however, have not been elucidated. Upregulation of the cyclooxygenase enzymes, and subsequently prostaglandins, potentially play a stimulatory role. Prostaglandins work through one of four EP receptors (EP1-EP4) and the effects mediated through EP4R specifically are thought to be the primary drivers of cancer development. In human T-cell LSA, overexpression of EP4R has been found and appears to protect LSA cells from apoptosis. The role of EP4R in human B-cell LSA is more nuanced. This study aims to evaluate the mRNA expression of the EP4R gene (ptger4) in canine B-cell and T-cell LSA. Archived canine lymph nodes with histologically confirmed B-cell and T-cell LSA, and reactive lymph nodes, were evaluated for EP4R mRNA expression using a novel RNA in situ hybridization technique (RNAscope). Quantification of RNAscope signals was completed with an advanced digital pathology image analysis system (HALO). Results were reported as copy number, H-score, and percent tumour cell expression of EP4R mRNA. All reactive, B-cell LSA, and T-cell LSA lymph nodes expressed EP4R mRNA. The mRNA copy number, H-score, and percent tumour cell expression of EP4R were higher in B-cell (p < .003) and T-cell (p < .001) LSA samples compared to reactive lymph node samples. There were no differences between B-cell LSA and T-cell LSA.

Application of mid‐infrared microscopic imaging for the diagnosis and classification of human lymphomas

Mid-infrared (MIR) microscopic imaging of indolent and aggressive lymphomas was performed including formalin-fixed and paraffin-embedded samples of six follicular lymphomas and 12 diffuse large B-cell-lymphomas as well as reactive lymph nodes to investigate benefits and challenges for lymphoma diagnosis. MIR images were compared to defined pathological characteristics such as indolent versus aggressive versus reactive, germinal centre versus activated cell-of-origin (COO) subtypes, or a low versus a high proliferative index and level of PD-L1 expression. We demonstrated that MIR microscopic imaging can differentiate between reactive lymph nodes, indolent and aggressive lymphoma samples. Also, it has potential to be used in the subtyping of lymphomas, as shown with the differentiation between COO subtypes, the level of proliferation and PD-L1 expression. MIR microscopic imaging is a promising tool for diagnosis and subtyping of lymphoma and further evaluation is needed to fully explore the advantages and disadvantages of this method for pathological diagnosis.

Seroprevalence of Anti-SARS-CoV-2 Antibodies in Blood Donors from Nuevo Leon State, Mexico, during 2020: A Retrospective Cross-Sectional Evaluation.

The progression and distribution of the SARS-CoV-2 pandemic are continuously changing over time and can be traced by blood donors’ serological survey. Here, we investigated the seroprevalence of anti-SARS-CoV-2 antibodies in blood donors in Nuevo Leon, Mexico during 2020 as a strategy for the rapid evaluation of the spread of SARS-CoV-2 and asymptomatic case detection. We collected residual plasma samples from blood donors who attended two regional donation centers from January to December of 2020 to identify changes in anti-SARS-CoV-2 IgG prevalence. Plasma samples were analyzed on the Abbott Architect instrument using the commercial Abbott SARS-CoV-2 IgG chemiluminescent assay. We found a total of 99 reactive samples from 2068 analyzed plasma samples, resulting in a raw prevalence of 4.87%. Donors aged 18–49 years were more likely to be seropositive compared to those aged >50 years (p < 0.001). Weekly seroprevalence increased from 1.8% during the early pandemic stage to 27.59% by the end of the year. Prevalence was 1.46-fold higher in females compared to males. Case geographical mapping showed that Monterrey city recorded the majority of SARS-CoV-2 cases. These results show that there is a growing trend of seroprevalence over time associated with asymptomatic infection that is unnoticed under the current epidemiological surveillance protocols.

SARS-CoV-2 Seroprevalence and Neutralizing Antibody Response after the First and Second COVID-19 Pandemic Wave in Croatia.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus with a pandemic spread. So far, a total of 349,910 SARS-CoV-2 cases and 7687 deaths were reported in Croatia. We analyzed the seroprevalence and neutralizing (NT) antibody response in the Croatian general population after the first (May–July 2020) and second (December 2020–February 2021) pandemic wave. Initial serological testing was performed using a commercial ELISA, with confirmation of reactive samples by a virus neutralization test (VNT). A significant difference in the overall seroprevalence rate was found after the first (ELISA 2.2%, VNT 0.2%) and second waves (ELISA 25.1%, VNT 18.7%). Seropositive individuals were detected in all age groups, with significant differences according to age. The lowest prevalence of NT antibodies was documented in the youngest (<10 years; 16.1%) and the oldest (60–69/70+ years; 16.0% and 12.8%, respectively) age groups. However, these age groups showed the highest median NT titers (32–64). In other groups, seropositivity varied from 19.3% to 21.5%. A significant weak positive correlation between binding antibody level as detected by ELISA and VNT titer (rho = 0.439, p < 0.001) was observed. SARS-CoV-2 NT antibody titers seem to be age-related, with the highest NT activity in children under 10 years and individuals above 50 years.

Drug-resistant andimmune-escapehepatitis B virus mutants,occult hepatitis B infection and coinfections in public hospital patients from Argentina.

Argentina exhibits low serological prevalence for Hepatitis B virus (HBV); however, occult hepatitis B infection (OBI) has been reported in blood donors, Amerindians and individuals coinfected with hepatitis C virus (HCV), and/or human immunodeficiency virus (HIV). The aim of this study was to analyze the genetic diversity of HBV and to evaluate serological marker associations and coinfections with HCV and HIV in patients attending and treated in a public hospital in the province of Buenos Aires, Argentina. A total of 189 HBV reactive samples (HBsAg and/or anti-HBc) were analyzed for HBV DNA characterization. All reactive samples were tested for anti-HCV and HIV-antigen/antibody using CMIA assays. Thirty-six samples exhibited detectable HBV DNA, 7 of which were OBI. HBV sequences were classified as subgenotypes A1, A2, B2, D3, F1b, F3 and F4. Mutations related to the ability to escape the host's immune response, resistance to antiviral therapy and progression to disease were found in patients, partly due to the variable sensitivity of HBsAg, the reverse transcriptase, the basal core promoter and the preCore. HCV and HIV prevalence was 10% and most of the genotypes found in the sequences were genotype 1 and B/F recombinant subtype, respectively. Of the total samples analyzed, 7 exhibited coinfections. This study shows the frequency of OBI, subgenotypedistribution, HBV mutations and coinfections, which may have important clinical implicationsin public hospital patients. Planned prevention, detection and treatment adherence are needed to reduce transmission and morbidity in vulnerable populations.

Application of anti-HCV and HCV RNA detection in intravenous drug users

Objective: To explore the diagnostic value of anti-HCV and HCV RNA so as to provide an accurate and efficient detection strategy for the diagnosis of HCV in intravenous drug users. Methods: 527 plasma samples from intravenous drug users were collected, and preliminary anti-HCV ELISA screening test was performed. A recombinant immunoblot assay (RIBA) was used as confirmatory assay for reactive antibody samples. All samples were tested for HCV RNA, followed by analysis of anti-HCV screening test, RIBA and HCV nucleic acid test results. Results: Anti-HCV ELISA results were reactive in 386 out of 527 intravenous drug users and non-reactive in 141. Among the 386 reactive antibody samples detected by RIBA, 370 cases were anti-HCV positive, 6 cases were anti-HCV indeterminate and 10 cases were anti-HCV negative. Anti-HCV ELISA and RIBA positive coincidence detection rate was 95.85% (370/386), and 70.21% (370/527) among intravenous drug users. HCV RNA was negative in all 10 anti-HCV RIBA non-reactive samples. 376 anti-HCV RIBA-positive and indeterminate samples were tested for HCV RNA, of which 56.93% (300/527) were current HCV infection, and 14.42% (76/527) were past HCV infection. Among 141 anti-HCV ELISA negative samples, the residual risk by anti-HCV ELISA screening for HCV RNA was 1.52% (8/527). HCV viral load distribution among intravenous drug users showed that the high viral load value (>10(7) IU/ml) and low viral load values (< 10(2) IU/ml) accounted for 1.95% and 2.27%, respectively, while the samples with viral load value of 1×10(2) ~ 1×10(7) IU/ mL accounted for 95.78% (295/308), and were mainly distributed in 1×10(5) ~ 1×10(6) IU/ml (37.99%). ELISA + RIBA + NAT assay detection strategies had differentiated 300 cases of current HCV infection, 76 cases of past HCV infection and 10 cases of false positive anti-HCV results, while ELISA+NAT assay detection strategies had only detected 300 cases of current HCV infection. However, of the 386 positive subjects screened for antibodies, 10 (2.59%) were undifferentiated false positives. Conclusion: Intravenous drug users are the high-risk population of HCV infection with high prevalence and high viral load. Anti-HCV screening for intravenous drug users will have a certain degree of residual risk. Therefore, anti-HCV ELISA screening and nucleic acid detection strategy can accurately diagnose the current infected patients; however, it cannot distinguish the false positive results of antibody screening.

Distinct SARS-CoV-2 antibody reactivity patterns in coronavirus convalescent plasma revealed by a coronavirus antigen microarray

A coronavirus antigen microarray (COVAM) was constructed containing 11 SARS-CoV-2, 5 SARS-1, 5 MERS, and 12 seasonal coronavirus recombinant proteins. The array is designed to measure immunoglobulin isotype and subtype levels in serum or plasma samples against each of the individual antigens printed on the array. We probed the COVAM with COVID-19 convalescent plasma (CCP) collected from 99 donors who recovered from a PCR+ confirmed SARS-CoV-2 infection. The results were analyzed using two computational approaches, a generalized linear model (glm) and random forest (RF) prediction model, to classify individual specimens as either Reactive or non-reactive against the SARS-CoV-2 antigens. A training set of 88 pre-COVID-19 specimens (PreCoV) collected in August 2019 and102 positive specimens from SARS-CoV-2 PCR+ confirmed COVID-19 cases was used for these analyses. Results compared with an FDA emergency use authorized (EUA) SARS-CoV2 S1-based total Ig chemiluminescence immunoassay (Ortho Clinical Diagnostics VITROS Anti-SARS-CoV-2 Total, CoV2T) and with a SARS-CoV-2 S1-S2 spike-based pseudovirus micro neutralization assay (SARS-CoV-2 reporter viral particle neutralization titration (RVPNT) showed high concordance between the three assays. Three CCP specimens that were negative by the VITROS CoV2T immunoassay were also negative by both COVAM and the RVPNT assay. Concordance between VITROS CoV2T and COVAM was 96%, VITROS CoV2T and RVPNT 93%, and RVPNT and COVAM 91%. The discordances were all weakly reactive samples near the cutoff threshold of the VITROS CoV2T immunoassay. The multiplex COVAM allows CCP to be grouped according to antibody reactivity patterns against 11 SARS-CoV-2 antigens. Unsupervised K-means analysis, via the gap statistics, as well as hierarchical clustering analysis revealed three main clusters with distinct reactivity intensities and patterns. These patterns were not recapitulated by adjusting the VITROS CoV2T or RVPNT assay thresholds. Plasma classified by COVAM reactivity patterns offers potential to improve CCP therapeutic efficacy CoV2T alone. The use of a SARS-CoV-2 antigen array can qualify CCP for administration as a treatment for acute COVID-19, and interrogate vaccine immunogenicity and performance in preclinical, clinical studies, and routine vaccination to identify antibody responses predictive of protection from infection and disease.

Dynamic mechanical behaviour and microstructure of Al/Teflon reactive materials

Dynamic compressive behavior of 2 kinds of Al/Teflon reactive materials samples are analyzed by using the Split Hopkinson pressure bar. The mass percentage of the samples is 26.5% Al and 73.5% Teflon. The particle size of Teflon is 30 µm, and the particle size of Al is 1.5 µm and 100 µm, respectively. The microstructure of the sample was studied by scanning electron microscope (SEM). The results show that Al/Teflon reactive materials undergoes compression-yield-unloading-enhancement stages during the process of dynamic compression. The dynamic compressive strength of Al/Teflon reactive materials samples prepared by Al1.5 µm/Teflon30 µm and Al100 µm/Teflon30 µm are 55 MPa and 47 MPa at the strain rate of 4 × 103 s−1, respectively. When the Al particle diameter is 100 µm in Al/Teflon material, the strength contribution of Al is larger. However the defect is more obvious after yield, the strength is weaker than that of Al1.5 µm/Teflon30 µm sample.