RESUMO
BackgroundCurrently used vaccines to protect from COVID-19 mostly focus on the receptor-binding domain (RBD) of the viral spike protein, and induced neutralizing antibodies have shown to be protective. However, functional relevance of vaccine-generated antibodies are poorly understood on variants-of-concern (VOCs) and mucosal immunity. MethodsWe compared specific antibody production against the S1 subunit and the RBD of the spike protein, the whole virion of SARS-CoV-2, and monitored neutralizing antibodies in sera and saliva of 104 BNT162b2 vaccinees and 57 individuals with natural SARS-CoV-2 infection. Furthermore, we included a small cohort of 11 individuals which received a heterologous ChAdOx1-S/BNT162b2 prime-boost vaccination. ResultsVaccinated individuals showed higher S1-IgG antibodies in comparison to COVID-19 patients, followed by a significant decrease 3 months later. Neutralizing antibodies (nAbs) were poorly correlated with initial S1-IgG levels, indicating that these might largely be non-neutralizing. In contrast, RBD IgGAM was strongly correlated to nAbs, suggesting that RBD-IgGAM is a surrogate marker to estimate nAb concentrations after vaccination. The protective effect of vaccine- and infection-induced nAbs was found reduced towards B.1.617.2 and B.1.351 VOCs. NAb titers are significantly higher after third vaccination compared to second vaccination. In contrast to COVID-19 patients, no relevant levels of RBD specific antibodies were detected in saliva samples from vaccinees. ConclusionsOur data demonstrate that BNT162b2 vaccinated individuals generate relevant neutralizing antibodies, which begin to decrease within three months after immunization and show lower neutralizing potential to VOCs as compared to the original Wuhan virus strain. A third booster vaccination provides a stronger nAb antibody response than the second vaccination. The systemic vaccine does not seem to elicit readily detectable mucosal immunity.
RESUMO
Efforts to contain the spread of SARS-CoV-2 have spurred the need for reliable, rapid, and cost-effective diagnostic methods which can easily be applied to large numbers of people. However, current standard protocols for the detection of viral nucleic acids while sensitive, require a high level of automation, sophisticated laboratory equipment and trained personnel to achieve throughputs that allow whole communities to be tested on a regular basis. Here we present Cap-iLAMP (capture and improved loop-mediated isothermal amplification). This method combines a hybridization capture-based RNA extraction of non-invasive gargle lavage samples to concentrate samples and remove inhibitors with an improved colorimetric RT-LAMP assay and smartphone-based color scoring. Cap-iLAMP is compatible with point-of-care testing and enables the detection of SARS-CoV-2 positive samples in less than one hour. In contrast to direct addition of the sample to improved LAMP (iLAMP), Cap-iLAMP does not result in false positives and single infected samples can be detected in a pool among 25 uninfected samples, thus reducing the technical cost per test to ~1 Euro per individual.
RESUMO
SARS-CoV-2 causes substantial morbidity and mortality in elderly and immunocompromised individuals, particularly in retirement homes, where transmission from asymptomatic staff and visitors may introduce the infection. Here we present a cheap and fast approach to detect SARS-CoV-2 in single or pooled gargle lavages ("mouthwashes"). With this approach, we test all staff at a nursing home daily over a period of three weeks in order to reduce the risk that the infection penetrates the facility. This or similar approaches could be implemented to protect hospitals, nursing homes and other institutions in this and future viral epidemics.
