Small numbers of leucocyte clusters (< 0.22 clusters per field) were observed in liver samples from mice inoculated with PBS, though no acid fast bacilli (AFB) were detected in any of these samples. Large differences in the mean ranked density of leucocyte clusters between strains were identified (p<0.001) with the wild type strain JD87/107 having the highest mean ranked densities of clusters (Figure  2b). Strain 2eUK2001 showed evidence of higher mean rank densities than the 316FUK2001 and IIUK2001 strains (p = 0.03). The ranked density of leucocyte clusters with AFB showed highly statistically significant differences between the means of MAP strains selleck chemicals (p<0.001), with the JD87/107 strain consistently showing

higher mean densities, with this effect being more pronounced from 8 weeks post infection (Figure  2c). The vaccine strains all tended to exhibit increasingly lower mean ranked densities over the lifetime of the experiment (p=0.002), with consistent patterns of differences between strains (p=0.008): strain IIUK2001 showed the largest mean rank densities, strain 316FUK2001 the lowest, with 2eUK2001 intermediate. The histopathology results show that all strains elicited

a similar inflammation at 4 weeks. Only thereafter some differences between the inflammatory responses to the strains became apparent. In addition, the analysis of mean bacterial counts and AFB positive clusters showed the reduced ability of the vaccine strains to survive and persist within mice. Overall, these Amisulpride results provide proof of attenuation of NVP-HSP990 mw the vaccine strains with respect

to a wild type MAP strain. Discussion In this study, we examined genomic and phenotypic characteristics of a panel of MAP vaccine strains obtained from several laboratories around the world including both low and high passage examples of the 316 F lineage. Using a mouse model, we assessed the virulence ofrepresentative clades of three vaccine strains (2e, II, 316 F) with respect to a virulent MAP clinical isolate. The vaccine strains were clearly attenuated with regard to their ability to survive and persist in the mice as evidenced from the reduced numbers of MAP recovered and reduced numbers of leucocyte clusters containing AFB in the livers. This supports previous studies showing decreased persistence of the same 316 F and 2e strains in calves after 8 months [29] and illustrates the utility of the C57BL/6 mouse model for virulence studies. Using a pan-genomic MAP/MAH microarray we demonstrated that the genomes of all but one of the 316 F strains in the test panel contain the same full genome complement as the reference virulent bovine MAP type II strain MAPK10. One 316 F strain obtained from Norway (316FNOR1960) contained a single deleted region (vGI-19) spanning 21 ORF’s (including 10 MAP specific genes). Two strains not of the 316 F lineage (2eUK2000 and IIUK2000) contained a different deleted region (vGI-20), identical in both strains, spanning 34 ORF’s (including 10 MAP specific genes).