Abstract
We read with interest the comments made by Goossens et al. (2007) concerning our recent publication (Enkhtuya et al., 2006). In our paper we demonstrated the specificity of rabbit anti-Bacillus anthracis (pXO1 and pXO2) Pasteur II spore IgG and its protective effect in mice against lethal challenge by pXO1+ and pXO2+ B. anthracis spores. The following are our comments addressing their concerns.
1. We are well aware that Bacillus cereus and Bacillus thuringiensis are closely related to B. anthracis, as they are classified into one group based on genomic analysis; thus, we examined the cross-reactivity of our rabbit anti-anthrax spore IgG to these three species plus Bacillus subtilis by indirect immunofluorescence staining. Fluorescence images were all taken with the same exposure time and conditions in order to compare the relative fluorescence intensity. As clearly stated in the text, we obtained remarkably strong fluorescence from B. anthracis spores, while in contrast there was no detectable fluorescence from images of other tested Bacillus spores, including B. cereus, B. thuringiensis and B. subtilis, in addition to a negative control. Due to space constraints, these data were not shown in the original paper (Enkhtuya et al., 2006). However, we are happy to include these findings here (Fig. 1). We are certain that anti-spore IgG obtained by immunization using formalin-fixed spores of plasmidless Pasteur II strain reacts specifically with B. anthracis spores.