Protective efficacy of IgA monoclonal antibodies to O and H antigens in a mouse model of intranasal challenge with Salmonella enterica serotype Enteritidis

Protective properties of immunoglobulin A (IgA) monoclonal antibodies (MAbs) directed against O and H antigens of Salmonella enterica serotype Enteritidis (S. enteritidis) were evaluated in a model of generalized infection after intranasal (i.n.) inoculation of BALB/c mice. Passive i.n. instillation of antibodies 1 h before i.n. challenge did not prevent infection, and mice developed rapid inflammatory response in the lower respiratory tract. The passive systemic immunization was partially protective and a single intravenous (i.v.) injection of both O and H antigen specific IgA antibodies prolonged survival period of the infected animals. Permanent secretion of 0:9 specific IgA MAb 177E6 into the respiratory tract in a "backpack" tumor model protected 50% of animals infected i.n. with a high dose of virulent S. enteritidis strain. Thus, secretory IgA (S-IgA) directed against 0:9 antigen alone can prevent bacterial invasion in the respiratory epithelium. (C) 2004 Elsevier SAS. All rights reserved.