Reliability of laboratory models in the analysis of TBP2 and other meningococcal antigens

The lack of experimental models suitable for the study of meningococcal pathogenicity led us to investigate if thoses actually in use (culture in iron-restricted media and animals models) provide results comparable with the responses observed in vivo during infection. In this work we studied three invasive strains cultured both in laboratory media and in human plasma, analysing the immune response elicited in mice against membrane antigens and comparing them with those seen using homologous human convalescent sera. Outer membrane protein profiles observed after culture in plasma were different and more complex than those obtained after growth in laboratory media. Analogous differences were observed in the antigenic profiles, detecting some antigens recognized by human, but not mouse sera, and vice sersa. However, the response to one of the major iron-regulated outer membrane antigens, the transferrin binding protein 2 (TBP2), was unaffected by the culture medium or the model, human or mouse, used for the analysis. In conclusion, we have found that results of antigenic analysis change depending on the culture conditions and animal models used. For the meningococcal antigen TBP2, growth in iron-restricted laboratory media and a mouse model provide results which correlate well with those observed using convalescent human serum from individuals recovered from infections. We suggest that careful analysis and evaluation of experimental results and their comparison with in vivo elicited immune responses are essential in order to get accurate extrapolations for experimental vaccine designs.