TABLE 2.

Results of histological examinations for tibiotarsal joint swelling and carditis 14 days after B. burgdorferi infection

B. burgdorferi strain	Inoculum dose (no. of bacteria)	Inflammation score for mice 1 to 5a
		Knee	Tibiotarsus	Carditis
B31 5A4 WT	100	+/++, +, +	+++, +++, +++	+, +, +
	1,000	+, +, +, +	+++, +++, ++, +++	+, +, +, +
	10,000	++, +, +	+++, +++, +++	+, +, +
B31 5A18 WT	100	+/−, +, +	++, ++, +++	+, +, +
	1,000	+, +, +, +	+++, +++, +++, ++	++, ++, +, +
	10,000	+++, +++, ++	+++, +++, ++	++, ++, +++
bgpmut	100	−, −, −, −, −	−, −, −, −, −	−, −, −, +, +
	1,000	+, +, +, +, +	+, +, +, +, +	+, ++, ++, ++, ++, ++
	10,000	+, ++, ++, ++, ++	+, +, ++, ++, ++	++, ++, ++, +++, +++
	100,000	++, ++, ++, +++, +++	++, +++, +++, +++, +++	+++, +++, +++, +++, +++
bgpcomp	100	+, +/++, +	++, ++, ++	+/−, +, +
	1,000	+, +, +	+++, +++, +++	+/−, +, +
	10,000	+, +, +	+++, +++, +++	+/−, +, +

^aThree to five mice were infected with each strain, and inflammation scores are listed in sequential order for each mouse (numbered 1 to 5). Scores ranged from − (no inflammation) to +++ (severe arthritis). For carditis, scoring was based upon the number of infiltrating white blood cells between cardiomyocytes, loss of cell structure, and the breakdown of structures surrounding blood vessels/perivascular cuffing. For joints, scoring was based on infiltration of white blood cells in and around periarticular structures, the presence of cells within the synovium, and thickening of articular surfaces. +/−, samples that showed the presence of histopathological changes without a large number of infiltrating immune cells.