The invention provides an immunogenicmolecular entity, a supramolecular assembly, and an antibodythat can be used to inhibit Gram-positive bacterialquorum sensing, prevent infection or development of adisease condition associated with a Gram-positive bacterialinfection. The invention also provides methods of inhibitingGram-positive bacterial quorum sensing, andmethods of preventing infection or development of a diseasecondition associated with a Gram-positive bacterialinfection.