A simple aptamer/gold nanoparticle aggregation-based colorimetric assay for oxidized low-density lipoprotein determination.

Oxidized low-density lipoprotein (oxLDL) is the leading cause of atherosclerosis and cardiovascular diseases. Here, we created a simple colorimetric assay for sensitive and specific determination of oxLDL using a selective aptamer coupled with salt-induced gold nanoparticle (AuNP) aggregation. The aptamer was chosen by Systematic Evolution of Ligands by Exponential Enrichment to obtain a novel selective sequence towards oxLDL (as 5'-CCATCACGGGGCAGGCGGACAAGGGGTAAGGGCCACATCA-3'). Mixing a 5 µM aptamer solution with an aliquot of a sample containing oxLDL followed by adding AuNP solution (OD = 1) and 80 mmol L-1 NaCl achieved rapid results within 19 min: linear response to oxLDL from 0.002 to 0.5 µmol L-1 with high selectivity, a recovery accuracy of 100-111% at the 95% confidence interval, and within-run and between-run precision of 1-6% and 1-5% coefficient variations, respectively. Artificial serum diluted at least 1:8 with distilled water, analyzed by the aptamer-based colorimetric assay, showed excellent correlation with conventional thiobarbituric acid reactive substances (TBARS) (R2 = 0.9792) as a rapid colorimetric method without the need for sample preparation other than dilution.

Breakthrough SARS-CoV-2 Omicron Variant in Individuals Primed with Heterologous Vaccines Enhances Inhibition Performance of Neutralizing Antibody to BA.2 Parental Lineage.

This study aims to analyze the neutralization ability against Omicron parental variants in five clusters of individuals with different Coronavirus disease (COVID-19) immunity backgrounds, including individuals receiving a homologous or heterologous vaccine without prior infection, recovered patients with homologous or heterologous vaccination, and recovery patients without vaccination. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) surrogate virus neutralization assay was performed on serum samples. Spearman correlation analysis showed that the percent inhibition against Omicron B.1.1.529 and BA.2 was significantly related to the period of serum collection (r = 0.730 and 0.787, p < 0.001, respectively). Very strong correlation between percent inhibition of neutralizing antibody against Omicron B.1.1.529 and BA.2 variants (rs = 0.973, p < 0.001) was also observed. The neutralizing activity of the sera from recovery patients receiving homologous and heterologous vaccine against the wild-type, B.1.1.529, and BA.2 Omicron variants was significantly higher (p < 0.001) than that of recovery patients without vaccination. This study robustly showed that the breakthrough SARS-CoV-2 Omicron variant in individuals who received homologous and heterologous vaccines had a high level of neutralizing activity against B.1.1.529 and BA.2 parental lineage of XBB subvariants. Therefore, the next-generation COVID-19 vaccine against emerging variants is needed to improve resilience against ongoing variants, particularly for persons who have never been infected.

Development, Analytical, and Clinical Evaluation of Rapid Immunochromatographic Antigen Test for SARS-CoV-2 Variants Detection.

The antigen rapid diagnostic test (Ag-RDT) is a useful diagnostic tool for the detection and management of COVID-19 spread. Global SARS-CoV-2 variant outbreaks have highlighted the need for a test capable of detecting SARS-CoV-2 variants with high sensitivity and a low limit of detection. This study aimed to develop and evaluate, both analytically and clinically, an antigen rapid diagnostic test (the KestrelTM COVID-19 Ag Rapid Test) for professional use. A lateral flow immunoassay-based diagnostic test kit was developed, and various aspects of its analytical performance were evaluated. This test kit was clinically evaluated by two independent laboratories and showed closely related results of 96.49% and 98.33% of sensitivity, 100% and 100% of specificity, and 99.01% and 99.44% of accuracy, respectively. A limit of detection was observed at values as low as 0.156 ng/mL for recombinant SARS-CoV-2 nucleocapsid protein. Moreover, the test kit successfully detected the recombinant SARS-CoV-2 nucleocapsid protein (NP) of wild-type, Alpha-, Beta-, Gamma-, Delta-, Epsilon-, Kappa-, and Omicron-variants as positive results. Therefore, the KestrelTM COVID-19 Ag Rapid Test may have potential use for effective COVID-19 screening, surveillance, and infection control in a variety of global SARS-CoV-2 variant outbreaks.

Chikungunya Fever in Southern Thailand, 2018.

Infection by the mosquito-borne chikungunya virus (CHIKV) causes acute febrile illness and debilitating arthralgia. Outbreaks are sometimes not recognized because of its clinical resemblance to the more common dengue fever ubiquitous in tropical countries. An upsurge of dengue-like illness was reported in Satun province located in southern Thailand during the rainy season in 2018. We investigated probable outbreak of CHIKV disease. We collected serum samples from 127 patients and tested for CHIKV infection based on nucleic acid and serological tests. CHIKV RNA amplified by real-time reverse-transcription polymerase chain reaction (RT-PCR) and IgM antibody against CHIKV were determined by immunochromatographic rapid test. Mosquitoes in the community were also trapped and tested for CHIKV. Conventional RT-PCR on initially positive samples was performed to obtain nucleotide sequences for subsequent phylogenetic analysis. In all, 39% (50/127) of the samples tested positive for CHIKV RNA, IgM, or both. Of these, CHIKV RNA was identified in 17% (21/127) of the samples. Fourteen percent (18/127) of the samples were simultaneously positive for both IgM and IgG, which suggest recent infection. One sample tested positive for both CHIKV IgM and RNA. Several samples from Aedes aegypti and Aedes albopictus mosquitoes were also CHIKV RNA-positive. Sequence analysis revealed that the Satun CHIKV belonged to the Indian Ocean lineage within the East/Central/South African (ECSA) clade with residues K211E and A226 in the E1 gene, and G205S and V264A in the E2 gene. The ECSA strain of CHIKV continues to evolve and possesses virulent potential despite causing prior outbreaks in the region.