| This study aims to compare the susceptibility of four mice strains to the attenuated spores of Bacillus anthracis, and determine a suitable animal model for the attenuated spore challenge. The spores of two B. anthracis attenuated strains A16Q1 (pXO1-, pXO2+) and A16PI2 (pXO1+, pXO2-) were used to challenge four mice strains (DBA/2, KM, ICR and BALB/c) by intraperitoneal injection, and the times of mice death were recorded. Then, completed to statistical analysis, calculated LD50, and drew survival curve. Relatively sensitive KM mice were used to study the virulence difference of different canSNP genotypes encapsulated and toxin auxotrophs spores (harboring different copy of pXO2). More sensitive DBA/2 mice were used to evaluate the effect of S-layer protein BA3338 on the virulence of the capsule-deficient spores. The results showed that the virulence of encapsulated and toxin auxotrophs B. anthracis spores were stronger than those of nonencapsulated toxin-producing strains for those four mice strains. DBA/2 mice had the best dose-dependent relationship to the B. anthracis attenuated spores and were the most sensitive, followed by KM mice, whereas ICR and BALB/c were quite insensitive to challenge. In this study, the applicability of DBA/2 mice and KM mice in the study of B. anthracis attenuated spores were determined. Using KM mice that are sensitive to encapsulated strain to evaluate the virulence difference of different canSNP genotypes. The results indicated that different canSNP genotypic B. anthracis containing the difference of pXO2 plasmid copy number conduced to different virulence of spore. DBA/2 mice were used to evaluate the effect of the S-layer protein BA3338 defect on the virulence of B. anthracis, indicated that the defect of BA3338 gene may lead to a decline in the virulence of B. anthracis. |
