Rabbit IgG(Immunoglobulin G) ELISA Kit

The gut is home to the body's largest population of plasma cells. In healthy individuals, IgA is the dominating isotype, whereas patients with inflammatory bowel disease also produce high concentrations of IgG. In the gut lumen, secretory IgA binds pathogens and toxins but also the microbiota. However, the antigen specificity of IgA and IgG for the microbiota and underlying mechanisms of antibody binding to bacteria are largely unknown. Here we show that microbiota binding is a defining property of human intestinal antibodies in both healthy and inflamed gut. Some bacterial taxa were commonly targeted by different monoclonal antibodies, whereas others selectively bound single antibodies. Interestingly, individual human monoclonal antibodies from both healthy and inflamed intestines bound phylogenetically unrelated bacterial species. This microbiota cross-species reactivity did not correlate with antibody polyreactivity but was crucially dependent on the accumulation of somatic mutations. Therefore, our data suggest that a system of affinity-matured, microbiota cross-species-reactive IgA is a common aspect of SIgA-microbiota interactions in the gut.

The ongoing coronavirus disease 19 (COVID-19) pandemic, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses a threat to human health. Despite this, many affected countries are now in the process of gradual lifting of COVID-19 restrictions that were initially implemented in response to the pandemic. The success of the so-called "exit strategy" requires continued surveillance of virus circulation in the community and evaluation of the prevalence of protective immunity among population. Serology tests are valuable tools for these purposes. Herein, SARS-CoV-2 full-length spike (S) recombinant protein was utilized to develop and optimize an indirect enzyme-linked immunoassay (ELISA) that enables a reliable detection of virus-specific IgG antibody in human sera. Importantly, the performance of this assay was evaluated utilizing micro-neutralization (MN) assay as a reference test. Our developed ELISA offers 100% sensitivity, 98.4% specificity, 98.8% agreement, and high overall accuracy. Moreover, the optical density (OD) values of positive samples significantly correlated with their MN titers. The assay specifically detects human IgG antibodies directed against SARS-CoV-2, but not those to Middle East respiratory syndrome coronavirus (MERS-CoV) or human coronavirus HKU1 (HCoV-HKU1). The availability of this in-house ELISA protocol would be valuable for various diagnostic and epidemiological applications.