Journal of clinical virology plus最新文献

The emergence of SARS-CoV-2 has caused worldwide pandemic of COVID-19. Infection is difficult to diagnose early as some patients remain asymptomatic and may carry this virus to other people. Currently, qRT-PCR is the widely accepted mode for detection. However, the need for sophisticated instrument and trained personnel may hinder its application, especially in remote and facility-lacking areas. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) may serve as a potential approach for detection of SARS-CoV-2 as the resources needed in its application is far less complex than those of qRT-PCR. Herein, we evaluated RT-LAMP based analytical method (COVIDNow), relative to qRT-PCR, in detecting SARS-CoV-2 by using 63 clinical respiratory samples. Based on our finding, COVIDNow exhibited sensitivity and specificity values of 87.5% and 80.6%, respectively. Taken together, RT-LAMP based detection of SARS-CoV-2 by utilizing COVIDNow might serves as a valuable diagnostic tool in the management of global COVID-19 pandemic condition.

Background

Measles, mumps, rubella, and varicella-zoster (MMRV) immunity testing is important in occupational screening of healthcare workers and at-risk populations.

Objectives

The goal of this study was to compare the performance of the Bio-Rad BioPlex 2200 MMRV multiplex fluorescence immunoassay (MFI) against two enzyme immunoassay (EIA) methods: the Bio-Rad Evolis Twin Plus measles, mumps, and varicella-zoster (MMV) IgG assay and the Abbott Architect Rubella IgG assay.

Study Design

Clinically uncharacterized serum specimens were obtained and analyzed using the Bio-Rad BioPlex assay and compared against the EIA methods.

Results

The Bio-Rad BioPlex demonstrated total agreement of 85.5% (95% confidence interval (CI), 78.0 to 90.7%), 92.7% (95% confidence interval (CI), 86.7 to 96.1%), 92.4% (95% confidence interval (CI), 86.9 to 95.7%), and 98.8% (95% confidence interval (CI), 93.7 to 99.8%) for measles, mumps, varicella-zoster, and rubella, respectively, against the current EIA methods. Furthermore, precision testing agreed with the manufacturer's package insert in 10 of 13 pooled samples.

Conclusion

These data indicate that the Bio-Rad BioPlex has comparable performance to the EIA methods.

The diagnosis of human immunodeficiency virus 1 (HIV) infections is reliant on viral nucleic acid testing (NAT). HIV viral load (VL) is generally measured in plasma samples.

We evaluated and compared plasma HIV VL results with those obtained using serum samples, the aim being to enable the use of serum in urgent contexts where plasma is not available. Our findings indicated a very high correlation between the HIV VL results obtained in plasma and in serum.

Objective

Lateral flow assays (LFA) are sensitive for detecting antibodies to SARS-CoV-2 proteins within weeks after infection. This study tested samples from immunocompetent adults, and those receiving treatments for chronic inflammatory diseases (CID), before and after mRNA SARS-CoV-2 vaccination.

Methods

We compared results obtained with the COVIBLOCK Covid-19 LFA to those obtained by anti-spike (S) ELISA.

Results

The LFA detected anti-S antibodies in 29 of 29 (100%) of the immunocompetent and 110 of 126 (87.3%) of the CID participants after vaccination. Semiquantitative LFA scores were statistically significantly lower in samples from immunosuppressed participants, and were significantly correlated with anti-S antibody levels measured by ELISA.

Conclusions

This simple LFA test is a practical alternative to laboratory-based assays for detecting anti-S antibodies after infection or vaccination. This type of test may be most useful for testing people in outpatient or resource-limited settings.

Background

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has caused over 6 million deaths world-wide. In the pre-vaccination era, we noted a 5·3% SARS-CoV-2 IgG antibody positivity rate in 81,624 subjects.

Methods

Utilizing assays for serum SARS-CoV-2 spike (S) protein antibody (Roche) and neutralizing antibody (Diazyme), both >90% IgG, we measured antibodies in 13,189 subjects in the post-vaccination era, and in 69 subjects before and 60 days after booster vaccination.

Results

In 2021, in 10,267 subjects, 25·0% had negative S protein levels (<0.80 U/L), 24·4% had low positive levels (0.80-250 U/L), and 50·7% had high positive levels (>250 U/L). Median neutralizing antibody levels were 1·16 and 2·06 AU/mL in the low and high positive groups, respectively. In 2022, we evaluated 2,016 subjects where samples were diluted 1:100 if S protein antibody levels were >250 U/L. Median S protein and neutralizing antibody levels were 2,065 U/L (86.3% positivity) and 2·68 AU/mL (68.0% positivity), respectively. Antibody levels were also measured in 69 subjects before and 60 days after receiving SARS-CoV-2 booster vaccinations. Treatment resulted in a 15-fold increase in S protein antibody levels from 1,010 to 17,236 U/L, and a 6-fold increase in neutralizing antibody from 1·51 to 12·51 AU/mL in neutralizing antibody levels, respectively (both P<0.00001), with a wide variability in response.

Conclusions

Our data indicate that by early 2022 86% of subjects had positive SARS-CoV-2 S protein antibody levels, and that these levels and neutralizing antibody levels were increased 15-fold and 6-fold, respectively, 60 days after SARS-Cov-2 booster vaccination.

With widespread global COVID-19 vaccine coverage, a scalable, cost-effective, and standardized tool to ascertain post-vaccine immunity is a dire need. Neither clinical evaluations of vaccine efficacy, nor live virus antibody neutralization assays fulfill these criteria. Commercially available anti-S binding immunological assays have the potential to fill this gap, but need to be systematically evaluated for their utility to serve as surrogates for the aforementioned, widely accepted tools of determining vaccine efficacy. In this study, we evaluated an anti-S binding immunological assay (Roche Elecsys Anti-SARS-CoV-2 S) by utilizing two hundred and fifty-five archived serum specimens, either pre-pandemic, or those exposed to natural infections or vaccines with their neutralizing titers pre-determined through a live virus, pseudotyped antibody neutralization assay. Roche Elecsys Anti-SARS-CoV-2 S demonstrated good sensitivity (98%) and specificity (99%), just as has been reported in some other previously conducted studies using this assay. Only a mild correlation, however, with the live virus pseudotyped lentivirus antibody neutralization assay (Spearman's r = 0.26) was observed. We conclude that, as such, Elecsys Anti-SARS-CoV-2 S has a high sensitivity and specificity for detecting anti-SARS-CoV-2 S proteins, though the assay does not always correlate well with live virus assays for quantitative outcomes.

Background

Anti-HCV immunoassays remain the primary serologic test for HCV screening among blood donors. Since 1990s, Anti-HCV assays have evolved and those currently available detect infection earlier and have improved sensitivity and specificity compared with older generation assays. The new Alinity s Anti-HCV II assay, with its innovative design, has improved sensitivity, which shall further enhance safety of blood.

Methods

Alinity s Anti-HCV II assay was evaluated at 2 blood services (HKRCBTS & SNBTS). The overall sensitivity was evaluated using known positive samples (n = 5 at HKRCBTS; 50 at SNBTS) and 3 seroconversion panels (panel members =14 at each site). A total of 7,532 blood donor samples were tested to determine the clinical specificity.

Results

The clinical sensitivity of the new assay was found to be 100% at both sites. HCV seroconversion panel detection rates were 57.1% (8/14) and 14.3% (2/14) for the Alinity s Anti-HCV II and Anti-HCV assays respectively, resulting in an improvement in seroconversion sensitivity of 42.8% for the Anti-HCV II assay over the Anti-HCV assay. The specificity of the Anti-HCV II assay was 100% at HKRCBTS, and 99.95% at SNBTS.

Conclusions

The Anti-HCV II assay detected all known positive specimens and was able to detect samples in seroconversion panels earlier compared to the Anti-HCV assay. The assay showed excellent clinical specificity and generated fewer false-reactive results and was found to be suitable for routine blood donor screening.

Background

Direct detection tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that bypass complicated nucleic acid/antigen purification steps are promising tools for the rapid diagnosis of coronavirus disease 2019 (COVID-19).

Methods

To determine the analytical and clinical diagnostic performances of the direct detection assays, we compared 6 direct molecular detection assays, including two loop-mediated isothermal amplification (LAMP) assays and one lateral flow antigen assay, against the reference extraction-based RT-PCR assay using 183 respiratory samples (87 nasopharyngeal swabs, 51 saliva samples, and 45 sputum samples).

Results

Analytical sensitivity analysis showed that the direct RT-PCR assay of Toyobo exhibited the lowest LOD of 1,000 copies/mL. Compared with the 80 positive and 103 negative samples based on the reference assay, the Toyobo assay had the highest positive percent agreement (PPA) of 96.3%, followed by the two direct RT-PCR assays of Takara and Shimadzu and one LAMP assay of Eiken (86.3–87.5%). The Fujirebio antigen assay had the lowest PPA of 44.7% among the assays tested. The negative percent agreement of these direct detection assays was 100%, except for the Eiken assay (96.3%).

Conclusions

Large differences in PPA existed among the direct detection tests. Laboratories need to take these characteristics into consideration before implementing these assays.

Background

SARS-CoV-2 rapid antigen tests (RATs) are in high demand for reducing the spread of SARS-CoV-2. Reduced involvement from health care professionals (HCPs) for collection and interpretation could significantly foster the wide-spread implementation of RATs, but data evaluating RATs, when used by lay people, is limited.

Objective

To valuate agreement between BD Veritor test results for self- and HCP-collected specimens, and visually- and analyzer-interpreted results.

Methods

Individuals with onset of COVID-19 symptoms within five days of enrollment had three nasal swabs collected; one self-collected and the other two HCP-collected. One HCP-collected swab was stored for future testing while the order of the other two (self and HCP) was randomized before testing. with the BD Veritor System for Rapid Detection of SARS-CoV-2. Results were first assessed visually, followed by interpretation with the analyzer.

Results

When self-collection was compared to HCP collection for SARS-CoV-2 detection, interpretation by analyzer resulted in positive percent agreement (PPA) of 94.7% (95% CI 82.7, 98.5) and negative percent agreement (NPA) of 99.0% (95% CI 97.5, 99.6). When visual interpretation was compared to analyzer-read results, collection by HCPs had a PPA of 97.4% (95% CI 86.5, 99.5) and NPA of 99.8% (95% CI 98.6, 100.0) while self-collection resulted in PPA of 94.9% (95% CI 83.1, 98.6) and NPA of 99.8% (95% CI 98.6, 100).

Conclusions

Similar PPA and NPA were observed for self- and HCP-collected specimens as well as visually- and analyzer-interpreted tests. The equivalence in performance supports the use of expanded collection and testing methods.