Invasive African nontyphoidal Salmonella requires high levels of complement for cell-free antibody-dependent killing

• DOI: 10.1016/j.jim.2012.10.005
• Publication Date: 2012-10-22T14:15:48Z
• Authors: Yun Shan Goh; Calman A. MacLennan
• Keywords: Serial dilution; Bacteremia

Nontyphoidal isolates of Salmonella (NTS), particularly Typhimurium, are a major cause invasive bacteremia in Africa. Despite this, no vaccine against NTS is currently available for use humans. If to be developed timely manner, there need develop assays assess its vivo efficacy. Assessment potential efficacy candidate vaccines preclinical models important proof-of-concept and reduces attrition clinical trials. Serum bactericidal (SBA) often used the functional activity vaccine-induced antibody responses targeted Gram-negative bacteria with results given as maximum dilution serum that can effect bacterial killing. Previously we have found evidence protective role antibody-induced complement-mediated killing African children using an undiluted whole SBA. However, endogenous complement diluted human sera limiting insufficient S. Typhimurium beyond two two-fold dilutions. In current study, examined requirements SBA baby rabbit (BRS) exogenous source complement. We amount required antibody-mediated much higher isolate D23580, compared laboratory LT2 Paratyphi A CVD1901. While 20% BRS was sufficient kill CVD1901, 75% needed D23580. Our findings demonstrate one concentration not suitable all isolates. To vaccines, it necessary optimize assay which targeted.