The protective capacity of anti-O4 antigen antibodies against Salmonella infection is influenced by the presence or absence of the O5 antigen. Issue 34 (22nd July 2020) - Elsheimer-Matulova, Marta
Highlights: Anti-O4 antigen IgG induced better protective immunity in mice against O5− S. Typhimurium than against O5+ S. Typhimurium. Macrophage uptake of O5+ S. Typhimurium opsonized with anti-O4 antigen IgG was impaired when compared to O5− S. Typhimurium. It is therefore necessary to include both O4 serological variants when developing a Salmonella vaccine using the O-antigen. Abstract: Anti-O-antigen antibodies, such as anti-O4 antigen IgG, induce protective immunity against Salmonella enterica serovar Typhimurium ( S . Typhimurium) infection. S . Typhimurium belongs to the group O4, which can be classified into two serological variants, namely factor O5 antigen positive (O5+) and factor O5 antigen negative (O5−). In this study, we determined the protective immunity induced by anti-O4 antigen IgG against O5+ and O5− S . Typhimurium infection in a mouse model. Unexpectedly, anti-O4 antigen IgG induced protection against O5− of S . Typhimurium, but not against O5+ of S . Typhimurium. We suggest that the affinity of the O4 antigen with anti-O4 antigen IgG is stronger in the O5− S . Typhimurium compared to the O5+ S . Typhimurium. Although anti-O4 antigen IgG has the potential to protect against S . Typhimurium infection, the effects of anti-O4 antigen IgG in protection against Salmonella infection differ depending on the presence or absence of the O5 antigen.