RESUMEN
Colorimetric RT-LAMP Assay is a diagnostic method that has attracted much attention because of its rapidity, simplicity, and accuracy compared to other disease diagnosis methods. Despite having many advantages, the RT-LAMP Colorimetric Assay has disadvantages, especially for kits that use phenol red as an indicator. The disadvantage derives from the input RNA/DNA samples containing high buffer levels, which causes no color change and false-negative results. This study aimed to develop and optimize the colorimetric RT-LAMP method on high-buffered SARS-CoV-2 RNA samples. We found that a temperature of 69°C for 50 minutes with the addition of post-treatment in the form of heating at 80°C for 10 minutes is an optimal condition for high-buffered SARS-CoV-2 samples. The condition proved effective in changing the result's color from red (negative) to yellow (positive). We also classified the analysis results based on the correlation between the Cycle threshold (Ct) value of SARS-CoV-2 viruses and the Optical Density (OD) value, which was quantified using a spectrophotometer at 415 nm (with a correlation value of-0.9084), where yellow color indicated Ct below 20, amber color indicated Ct between 20 and 30, orange color indicated Ct between 30 and 35, and red indicated Ct more than 35 (negative). In conclusion, this study successfully detects the SARS-CoV-2 virus in high-buffered samples using Phenol Red Colorimetric RT-LAMP Assay, with a sensitivity of 85% for Ct Cutoff 40. © 2023, Bogor Agricultural University. All rights reserved.
RESUMEN
One of the main antigen that can be used for serological testing is the nucleocapsid (N) which is the most abundant viral-derived protein in SARS-CoV-2 where this virus can cause COVID19 disease. The aim of this study was to develop the SARS-CoV-2 N recombinant protein using Escherichia coli expression system. A total of 1,089 nucleotides encoding 362 amino acids of SARS-CoV-2 N was cloned to pET-14b vector. The plasmid then expressed in E. coli BL21 (DE3) and induced with 1.0 mM IPTG (Isopropyl-β-d-1-thiogalactopyranoside). The cell was harvested using denaturation lysis buffer due to inclusion body formation of SARS-CoV-2 N protein. Dialysis processed and concentrated using PEG-6000 resulted 0.992 mg/ml protein yield. Analysis of SARS-CoV-2 N recombinant protein using SDS-PAGE technique showed approximately 37.0 kDa specific band target protein. Application of this SARS-CoV-2 N recombinant protein to vaccinated and non-vaccinated antibody serum samples using ELISA technique indicated the significant result of optical density mean at 0.603 and 0.135, respectively. This study revealed that the production of SARS-COV-2 N recombinant protein could be carried out in E. coli expression system under denatured conditions, therefore the methods are more effective in producing the protein as a basic material in immuno-diagnostic assay. © 2023, Bogor Agricultural University. All rights reserved.
RESUMEN
COVID-19 caused by SARS-CoV-2 poses a major threat to the global community, particularly in Indonesia. Countermeasures to prevent the spread of this disease have also been implemented, including the implementation of a vaccination program. An immunoassay technique that can be used to analyze antibodies that might develop following vaccination is the indirect enzyme-linked immunosorbent assay (ELISA). We produced the recombinant spike protein used in this study. The optimization comprised adjusted concentrations of spike recombinant protein (5 and 10 ng/mL), blocking agent (2.5% and 5%), and conjugate (1:1000 and 1:5000). The optimal conditions in this study included a spiked concentration of 10 ng/mL, a blocking agent concentration of 5%, sample dilution of 1:33, and a conjugate concentration of 1:1000. The intra-assay value of this optimized indirect ELISA was 7.3, and the inter-assay value was 5.3. The commercial MyBioSource kit and immunodiagnostic were utilized as a reference in the T-test, with P-values of 0 and 0.313, indicating that the recombinant protein in-house ELISA kit in this study demonstrated the same ability as the commercial immunodiagnostic kit in detecting SARS-CoV-2 antibodies, allowing it to be used for post-vaccination efficacy evaluation. © 2022, Universitas Indonesia. All rights reserved.
RESUMEN
The present pandemic that is caused by COVID-19 and previously by the clone of the methicillin-resistant staphylococcus aureus (MRSA) has threatened human life. This condition requires materials that can break the chain of transmission from human to human and from the environment to human. This study aimed to evaluate the quality of alcohol-based hand antiseptic using WHO-recommended formulation based on the stability of the formulation, the risk of irritation, and the ability to kill bacteria. Assessments on the presence of rancidity, clarity, discoloration, final alcohol content, and skin irritation risk were done to know the quality of the product. Methicillin-resistant staphylococcus aureus (MRSA) was used to assess the percentage of bacterial killing power. The selected bacteria were bacteria that are commonly found in the hospital environment. The results showed that from four variants tested, MK.IV had good stability compared to other formulations. In terms of irritation risk, twenty-three selected subjects could well tolerate the formula. The results of the killing efficacy against MRSA showed that the antiseptic could kill 99.90% of the bacteria at the 1st, 2nd, and 5th minute. A selected manufacturer's product also showed the same killing efficacy at the 1st, 2nd, and 5th minute. The effective value of the antiseptic for each contact time was ≥ 90%.