Performance assessment of 11 commercial serological tests for SARS-CoV-2 on hospitalised COVID-19 patients

BACKGROUND

Commercial availability of serological tests to evaluate immunoglobulins (Ig) targeting severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has grown exponentially since the start of the coronavirus disease 2019 (COVID-19) outbreak. Thorough validation of these tests is important before use as epidemiological tools to infer seroprevalence in specific populations and as diagnostic tools to complement molecular approaches (e.g., quantitative reverse transcription-polymerase chain reaction).

METHODS

Commercial serological tests from 11 suppliers were assayed side-by-side using 126 samples from SARS-CoV-2-infected inpatients and 36 from healthy and HIV-infected individuals.

RESULTS

The majority of the tests assayed have >95% specificity. For the sensitivity calculation, samples were stratified by days since symptoms onset; sensitivity peaks at 16-21 days for IgM and IgA (maximum 91.2%, Euroimmun) and, dependant on the test, at 16-21 or >21 days for IgG (maximum 94.1%, Snibe). Data from semiquantitative tests show that patients with a severe clinical presentation have lower levels of Ig targeting SARS-CoV-2 at <10 days since symptoms onset and higher levels at >21 days, compared to patients with a non-severe presentation.

CONCLUSIONS

This study highlights the heterogeneity of sensitivity and generally high specificity of the serological tests and establishes a basis for their usefulness to complement diagnostic techniques and population seroprevalence studies.

Disposable microfluidic micromixers for effective capture of Cryptosporidium parvum oocysts from water samples

Background

Protecting drinking water supplies from pathogens such as Cryptosporidium parvum is a major concern for water utilities worldwide. The sensitivity and specificity of current detection methods are largely determined by the effectiveness of the concentration and separation methods used. The purpose of this study is to develop micromixers able to specifically isolate and concentrate Cryptosporidium, while allowing in situ analysis.

Results

In this study, disposable microfluidic micromixers were fabricated to effectively isolate Cryptosporidium parvum oocysts from water samples, while allowing direct observation and enabling quantification of oocysts captured in the device using high quality immunofluorescence microscopy. In parallel, quantitative analysis of the capture yield was carried out by analyzing the waste from the microfluidics outlet with an Imaging Flow Cytometer. At the optimal flow rate, capture efficiencies up to 96% were achieved in spiked samples.

Conclusions

Scaled microfluidic isolation and detection of Cryptosporidium parvum will provide a faster and more efficient detection method for Cryptosporidium compared to other available laboratory-scale technologies.

Efficient microfluidic negative enrichment of circulating tumor cells in blood using roughened PDMS

Depletion of >99.7% WBCs enabling tumor cell recovery from blood with nano-rough PDMS microfluidic negative enrichment devices functionalised with anti-CD45.

Detection of markers of cardiovascular and renal risk in Cuba: Isle of Youth Study (ISYS)

Chronic vascular diseases constitute a growing global health problem.

OBJECTIVES

To (a) determine marker positivity for renovascular damage in the total adult population of the Isle of Youth, Cuba; (b) describe marker association with common risk factors for renal and related chronic vascular conditions, and (c) identify best predictors of renovascular damage.

METHODS

Previous informed consent was obtained, the population studied was 55,646, and subjects were aged ≥20 years. Blood pressure, weight and height were measured and a questionnaire applied. Urine markers for renovascular damage (hematuria, proteinuria and microalbuminuria) were also determined.

RESULTS

Positive markers were detected in 21.3%: hematuria (12.6%), microalbuminuria (6.8%), proteinuria (0.9%), and proteinuria + hematuria (0.9%). Risk factors were highly prevalent: 15.1% were aged ≥60 years; 32.3% overweight, 13.9% obese, and 25.1% smokers. Prevalence of high blood pressure (30%), diabetes mellitus (5.4%) and cardiovascular disease (5%) was also high, while cerebrovascular disease registered 0.9%. Markers were more prevalent in older people and in those suffering from diabetes mellitus, high blood pressure, cardiovascular and cerebrovascular disease, overweight or obesity. Risk factor regression tree analysis identified hypertension as the best predictor of renovascular damage.

CONCLUSIONS

Adult population-wide screening revealed hidden morbidity and permitted better risk stratification. Results serve to inform community-based multidisciplinary and intersectoral disease prevention and management.

[Hematophagic activity of and environmental effect on the main malaria vector in Cuba: Anopheles albimanus]

An ecological study of Anopheles (N) albimanus in a suburban population of Camagüey province was carried out using a human bait in two trap points (indoor and outdoor). A higher quantity of females in the rainy season was observed together with a marked exophagic trend with peak activity in the early hours of the evening outdoor and in the early hours of the morning indoor. The abiotic influence on the fluctuation of the anophele population in both trap station was proved.

[The evolution of resistance in a Culex quinquefasciatus strain starting from selection with the pyrethroid insecticide lambdacyhalothrin]

The resistance change to different insecticides in Culex quinquesfasciatus strain select at the laboratory with doses of pyrethroid lambdacyhalothrin that would cause a larva mortality of 90% were studied. It was attained an increase of the resistance to this insecticide of 144.5 times compared with the original level, and it was obtained a resistant strain (287x). There was an increase of the levels of resistance to methyl-pyrimifos (2.4 times), propoxur (6 times), DDT (5.2 times), clorpirifos (22 time), cypermethrin (67.5 times), and deltamethrin (20.2 times). The frequencies of the genes that codify for the elevated esterases enzymes and for the modified acetylcholinesterase reached their maximum value. Significant changes were observed in the phenotypes for esterases in the electrophoresis in polyacrylamide gels. It was detected synergism of DEF and PB with lambdacyhalothrin. Therefore, the elevated esterases and the esterases of multiple function may contribute to resistance.

[3 combinations of esterases and their relation with the resistance to organophosphate, carbamate, and pyrethroid insecticides in Culex quinquefasciatus Say, 1823 (Diptera: Culicidae) in Cuba]

The possible relationship between different patterns of esterases and the resistance to various types of insecticides was analyzed by bioassays, biochemical tests, and electrophoresis carried out in a population of Culex quinquefasciatus from Camagüey and in three colonies obtained from it by family selection. The original population was heterogeneous and presented 8 combinations of esterases in polyacrylamide gel. A3A6B6, B1B6 and B1A6B6 were the most frequent of them and characterized each selected colony. Every studied colony, including the parental one, showed different levels of resistance to diverse insecticides. Only the resistance to propoxur showed less variation. In every colony it seems to exist a combination of resistance mechanisms; however, the differences found in tests with DEF synergized insecticides show that the different bands of zymograms may represent esterases contributing in a different way to resistance.

Morphometric characterization of normal and abnormal human zygotes

Human zygotes (n = 278) from 96 in-vitro fertilization gonadotrophin-stimulated cycles were photographed in their pronuclear stage (16-18 h post-insemination). Normal morphological fertilization (two pronuclei) was observed in 215 zygotes, 17 showed only one pronucleus, 40 showed three pronuclei and six showed four. Area, perimeter and maximum and minimum diameters of each zygote and pronucleus were measured using an IBAS 2000 (Kontron) image analyser. When the four groups were compared, whole zygotes did not show any morphometric difference. However, pronuclei from these groups showed that a high number of pronuclei was directly related to small pronuclei. Differences in pronuclear size and a linear increase in the nucleus/cytoplasm relationship were found which varied with the number of pronuclei.