T Cell Receptor Sequences Amplified during Severe COVID-19 and Multisystem Inflammatory Syndrome in Children Mimic SARS-CoV-2, Its Bacterial Co-Infections and Host Autoantigens.

Published hypervariable region V-beta T cell receptor (TCR) sequences were collected from people with severe COVID-19 characterized by having various autoimmune complications, including blood coagulopathies and cardiac autoimmunity, as well as from patients diagnosed with the Kawasaki disease (KD)-like multisystem inflammatory syndrome in children (MIS-C). These were compared with comparable published v-beta TCR sequences from people diagnosed with KD and from healthy individuals. Since TCR V-beta sequences are supposed to be complementary to antigens that induce clonal expansion, it was surprising that only a quarter of the TCR sequences derived from severe COVID-19 and MIS-C patients mimicked SARS-CoV-2 proteins. Thirty percent of the KD-derived TCR mimicked coronaviruses other than SARS-CoV-2. In contrast, only three percent of the TCR sequences from healthy individuals and those diagnosed with autoimmune myocarditis displayed similarities to any coronavirus. In each disease, significant increases were found in the amount of TCRs from healthy individuals mimicking specific bacterial co-infections (especially Enterococcus faecium, Staphylococcal and Streptococcal antigens) and host autoantigens targeted by autoimmune diseases (especially myosin, collagen, phospholipid-associated proteins, and blood coagulation proteins). Theoretical explanations for these surprising observations and implications to unravel the causes of autoimmune diseases are explored.

The incidence of irritable bowel syndrome among community subjects with previous acute enteric infection.

The purpose of this study was to determine the incidence of postinfectious irritable bowel syndrome (IBS) among community subjects with positive stool studies. This was a prospective cohort study whereby all individuals with stool-positive acute enteric infection (AEI) were recruited from 3 health regions in Ontario, Canada. Each person completed questionnaires regarding preinfectious bowel habit and their bowel habit 3 months postinfection. Manning and Rome I criteria were used to diagnose irritable bowel syndrome. Two hundred thirty-one patients participated. Forty had preexisting IBS and were excluded. Of the remaining 191 patients, 7 developed irritable bowel syndrome, for an incidence of 3.7% (95% confidence interval: 1.0-6.3%). Fever during AEI was the only identifiable risk factor for developing postinfectious IBS (odds ratio, 11.96; P = .02). The incidence of postinfectious IBS in community subjects is 3.7%. Fever during the AEI may be an important risk factor for this condition.