Gold-based paper for antigen detection of monkeypox virus.

In 2022, the outbreak of the monkeypox virus occurred in many non-endemic countries, and the World Health Organization (WHO) assessed that this outbreak was "atypical". The establishment of a rapid and effective assay that can be used for the early diagnosis of monkeypox virus infection is crucial for outbreak prevention and control. In this study, the monkeypox virus A29 protein and the homologous vaccinia virus A27 protein and cowpox virus 162 protein were expressed in Escherichia coli BL21 for screening. We synthesized the monkeypox virus A2917-49 peptide as the immunogen and obtained 25 monoclonal antibodies (mAbs) against the A29 protein using mouse hybridoma techniques. Then an immunochromatographic test strip method for detecting A29 was established. The strips utilizing mAb-7C5 and 5D8 showed the best sensitivity and lowest limit of detection: 50 pg mL-1 for purified A29 and specificity tests showed that the strips did not cross-react with other orthopox viruses (vaccinia virus or cowpox virus) as well as common respiratory pathogens (SARS-CoV-2, influenza A and influenza B). Therefore, this method can be used for early and rapid diagnosis of monkeypox virus infection by antigen detection.

Rapid colloidal gold immunochromatographic assay for the detection of SARS-CoV-2 total antibodies after vaccination.

An epidemic caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2) spread globally in just a few months. To prevent the further spread of the virus, millions of people around the world have been vaccinated for COVID-19. Although the plaque reduction neutralization test (PRNT) has become the gold standard method for determining neutralizing antibodies, this method has many limitations; therefore, there remains an urgent need for a quick and accurate technique to evaluate the immune efficacy of COVID-19 vaccines. Here, after the recombinant expression of the SARS-CoV-2 spike protein receptor binding domain (S-RBD), we established a colloidal gold immunochromatographic assay (GICA) based on the principle of a double antigen sandwich for the detection of total antibodies in sera. Under the developed conditions, the GICA was capable of the rapid detection of SARS-CoV-2 total antibodies within 15 min. In addition, the anti-S-RBD antibodies measured by the GICA had a good correlation with the results measured by ELISA, indicating that the GICA may be used as a rapid tool for the detection of neutralizing antibodies derived from SARS-CoV-2 infection. Clinical detection was performed using serum samples obtained from 40 subjects who had received their two doses of the COVID-19 vaccine and 20 unvaccinated serum samples. We found that our method had high sensitivity and specificity; therefore, our convenient and rapid GICA method could preliminarily evaluate the protection rate and effectiveness of vaccines by monitoring total antibody levels.