Differential Killing of Salmonella enterica Serovar Typhi by Antibodies Targeting Vi and Lipopolysaccharide O:9 Antigen

• DOI: 10.1371/journal.pone.0145945
• Publication Date: 2016-01-07T18:46:01Z
• Authors: Peter J. Hart; Colette M. O’Shau...; Matthew K. Siggins; Saeeda Bobat; Robert A. Kingsley; David A. Goulding; John A. Crump; Hugh Reyburn; Francesca Micoli; Gordon Dougan; Adam F. Cunningham; Calman A. MacLennan
• Keywords: Salmonella enterica; Salmonella enteritidis

Salmonella enterica serovar Typhi expresses a capsule of Vi polysaccharide, while most serovars, including S. Enteritidis and Typhimurium, do not. Both express the lipopolysaccharide O:9 antigen, yet there is little evidence cross-protection from anti-O:9 antibodies. Vaccines based on polysaccharide have efficacy against typhoid fever, indicating that antibodies confer protection. Here we investigate role in antibody-dependent complement- phagocyte-mediated killing Salmonella. Using isogenic Vi-expressing non-Vi-expressing derivatives show inherently more sensitive to serum blood than Typhimurium. expression confers increased resistance both modalities human blood. The associated with reduced C3 C5b-9 deposition, decreased overall antibody binding Typhi. However, purified anti-Vi presence complement are able kill Salmonella, by inversely related expression. Human depleted antigens other retains ability bacteria. Our findings support protective for preventing phagocyte can be overcome specific antibodies, but only limited extent