Riment III was done using independent samples T-test. In the joint A-836339 web diameter measurements, animal-specific means were used as independent observations. Statistical significance was determined as p0.05. When comparing B. burgdorferi infected mice to non-infected controls, Bonferroni correction was used. In the serum antibody and bacterial load analysis Post Hoc comparisons between means were done with Dunnett t test when there was a clear control, otherwise Tukey’s honestly significant difference test was used.Results Arthritis development in dbpAB/dbpAB, dbpAB/dbpA, dbpAB/ dbpB and dbpAB infected miceAn initial analysis (Experiment I) of the development of joint manifestations in mice infected the three different B. burgdorferi strains expressing either DbpA, DbpB or both DbpA and B, or with the strain lacking DbpA and B expression was performed. The joint diameter graph shows that dbpAB/dbpAB is the only strain that causes a clear and prominent joint swelling with a peak at four weeks (Fig. 2A, group 2). All mice were B. 1471-2474-14-48 burgdorferi culture positive in at least two of the three collected tissue samples (ear, bladder, joint) at seven weeks of infection (Table 1). These results show journal.pone.0174109 that all studied strains cause a disseminated infection in mice, but only the strain expressing both DbpA and B cause joint manifestations. Thus, for the further studies of arthritis development and post-treatment persistence, dbpAB/dbpAB and dbpAB were selected.Long-term follow-up of arthritis in dbpAB/dbpAB and dbpAB infected miceIn Experiment II, weekly joint diameter measurements were continued until week 15. The joint diameter graph shows that dbpAB/dbpAB caused an evident joint swelling now with two statistically significant (P 0.05) peaks at 4 and 9 weeks and with a slight amelioration towards the end of the follow up (Fig. 2B, group 7). In contrast, the joint swelling caused by dbpAB (group 8) was mild and late onset emerging only at 10 weeks of the infection and showing statistically significant difference from the uninfected control at that time point (P 0.05). On histological evaluation, findings in the joints at 15 weeks of dbpAB/dbpAB infected mice showed thickening of the synovial membrane with proliferation of synovial lining cells, fibroblast and buy LDN193189 capillary proliferation as well as a mild chronic inflammation containing mainly lymphocytes (Fig. 2D). In addition, the articular cartilage surface showed mild degenerative changes. The findings in the joints of dbpAB mice were minor and showed minimal thickening of the synovium consisting mainly of synovial fibroblasts, while no inflammatory cells, capillary proliferation or articular cartilage surface damage were seen (Fig. 2E). These results indicate that dbpAB/dbpAB causes a clear joint swelling and histologically evident arthritic lesions, while dbpAB induces late onset swelling and only minor arthritis.Progression of the long-term infectionIn experiment II, B. burgdorferi culture of ear biopsy samples taken at 6 and 9 weeks of the infection demonstrated that all dbpAB/dbpAB and three out of four dbpAB (transient infection in one mouse) infected mice developed disseminated infection (Table 2, groups 7 and 8).PLOS ONE | DOI:10.1371/journal.pone.0121512 March 27,6 /DbpA and B Promote Arthritis and Post-Treatment Persistence in MiceFig 2. Joint swelling and histology. In experiment I (A), II (B) and IV (C), the development of joint swelling was monitored by measuring the medio-lateral diameter of.Riment III was done using independent samples T-test. In the joint diameter measurements, animal-specific means were used as independent observations. Statistical significance was determined as p0.05. When comparing B. burgdorferi infected mice to non-infected controls, Bonferroni correction was used. In the serum antibody and bacterial load analysis Post Hoc comparisons between means were done with Dunnett t test when there was a clear control, otherwise Tukey’s honestly significant difference test was used.Results Arthritis development in dbpAB/dbpAB, dbpAB/dbpA, dbpAB/ dbpB and dbpAB infected miceAn initial analysis (Experiment I) of the development of joint manifestations in mice infected the three different B. burgdorferi strains expressing either DbpA, DbpB or both DbpA and B, or with the strain lacking DbpA and B expression was performed. The joint diameter graph shows that dbpAB/dbpAB is the only strain that causes a clear and prominent joint swelling with a peak at four weeks (Fig. 2A, group 2). All mice were B. 1471-2474-14-48 burgdorferi culture positive in at least two of the three collected tissue samples (ear, bladder, joint) at seven weeks of infection (Table 1). These results show journal.pone.0174109 that all studied strains cause a disseminated infection in mice, but only the strain expressing both DbpA and B cause joint manifestations. Thus, for the further studies of arthritis development and post-treatment persistence, dbpAB/dbpAB and dbpAB were selected.Long-term follow-up of arthritis in dbpAB/dbpAB and dbpAB infected miceIn Experiment II, weekly joint diameter measurements were continued until week 15. The joint diameter graph shows that dbpAB/dbpAB caused an evident joint swelling now with two statistically significant (P 0.05) peaks at 4 and 9 weeks and with a slight amelioration towards the end of the follow up (Fig. 2B, group 7). In contrast, the joint swelling caused by dbpAB (group 8) was mild and late onset emerging only at 10 weeks of the infection and showing statistically significant difference from the uninfected control at that time point (P 0.05). On histological evaluation, findings in the joints at 15 weeks of dbpAB/dbpAB infected mice showed thickening of the synovial membrane with proliferation of synovial lining cells, fibroblast and capillary proliferation as well as a mild chronic inflammation containing mainly lymphocytes (Fig. 2D). In addition, the articular cartilage surface showed mild degenerative changes. The findings in the joints of dbpAB mice were minor and showed minimal thickening of the synovium consisting mainly of synovial fibroblasts, while no inflammatory cells, capillary proliferation or articular cartilage surface damage were seen (Fig. 2E). These results indicate that dbpAB/dbpAB causes a clear joint swelling and histologically evident arthritic lesions, while dbpAB induces late onset swelling and only minor arthritis.Progression of the long-term infectionIn experiment II, B. burgdorferi culture of ear biopsy samples taken at 6 and 9 weeks of the infection demonstrated that all dbpAB/dbpAB and three out of four dbpAB (transient infection in one mouse) infected mice developed disseminated infection (Table 2, groups 7 and 8).PLOS ONE | DOI:10.1371/journal.pone.0121512 March 27,6 /DbpA and B Promote Arthritis and Post-Treatment Persistence in MiceFig 2. Joint swelling and histology. In experiment I (A), II (B) and IV (C), the development of joint swelling was monitored by measuring the medio-lateral diameter of.
