Stopping Strep Throat With Antibodies in Healthy Adults.

This research group has previously established a safe and reliable model of experimental human streptococcal pharyngitis (a 'strep throat' human challenge model). The CHIVAS-IgG study will use this model to understand the ways in which antibodies help protect humans against strep throat infections. Carefully screened healthy adults who are at very low risk of complicated strep disease will be admitted to a clinical trials unit where they will be randomly allocated to receive a licensed commercial 'intravenous immunoglobulin' product that is a mixture of antibodies from thousands of humans, or a placebo ('saline' or salty water), by intravenous injection. About a week after the injection of antibodies or saline, they will have strep throat bacteria (Streptococcus pyogenes) 'painted' with a swab on the back of their throat, as this research group has done previously for over 100 healthy adults. The participants will be observed closely for about 5 days to see if they develop symptoms (sore throat) and signs (red throat, big tonsils, sore glands) of strep throat. During that time, multiple throat and nasal swabs will be collected along with saliva samples, blood tests, and photos. Before discharge from the clinical trials unit, every participant will be treated with antibiotics to make sure any strep bacteria is removed. Participants will return for study visits at about 1 week and 1 month later, to check on how they are feeling and to collect more samples to understand how their immune system responds to the strep challenge. This study is an important step on the way to developing a vaccine to prevent strep throat, strep skin infections, and dangerous Streptococcus pyogenes diseases like invasive infections and post-infectious problems like rheumatic heart disease.