Strategies of statistical image analysis of 2D immunoblots: The case of IgG response in experimental Taenia crassiceps cysticercosis

A procedure is described to measure the diversity and enrich the meaning and usefulness of the information contained in 2D immunoblot images of the reaction between a complex mixture of parasite antigens and the complex set of antibodies usually present in the sera of infected individual hosts. The procedure and results are illustrated by the experimental infection of 30 mice (three strains, both sexes, 5 mice in each strain × sex combination) with Taenia crassiceps cysticerci, thirty days after the challenge. The exercise revealed a significant positive correlation of parasite loads with the hosts' IgG response, in association with their genetic background and less clearly with their sex, all in the midst of a remarkable diversity of both response variables among individual mice. After superimposing a 10 × 10 grid upon the 2D immunoblots some 10% of the positive grid-cells (those who had at least one spot) were positively correlated, suggesting shared epitopes between different antigen spots and/or similar factors controlling different antibody-producing cell clones. Also, a significant correlation was found between many of the positive grid-cells with high values of ∑parasites, but none with low. Thus, the procedure provided many clues for the selection of antigen spots useful to improve immunodiagnosis of cysticercosis and weakened the inclusion of any as vaccine candidate(s). However, some 16 antigen spots were shared almost exclusively by the resistant strains and could relate to protection. The procedure here illustrated may be used in other infections to assess and identify the relevance of antibodies in diagnosis and prevention, as well as provides a measurement of the expected diversity in the hosts' antibody response to the pathogen and of the possible relations between the individual responses towards different antigens contained in the mixture.