Table 1.

Summary of histopathologic scoring of naïve mouse spleens, and spleens of mice infected with wild-type or ΔrpoE1 B. abortus.

	Naïve		B. abortus WT		B. abortus ΔrpoE1
Week Post-infection (wpi)	1	9	1	9	1	9
white pulp to red pulp ratio	Normal (≈ 1:1)	Normal (≈ 1:1)	Decrease Score 1	Decrease Score 3	Decrease Score 1	Decrease Score 0.5
Average lymphoid follicles per field	8 to 12	8 to 12	Decrease Score 1	Decrease Score 2	Decrease Score 1	Decrease Score 0.5
Size of follicles	normal	normal	Decrease Score 1	Decrease Score 1	Decrease Score 1	Score 0
Marginal zone depletion	normal	normal	Increase Score 1	Increase Score 2	Increase Score 1	Increase Score 0-1
Extramedullary hematopoiesis	minimal	minimal	Increase Score 2	Increase Score 2	Increase Score 1	Increase Score 0-1
Histiocytic proliferation	none	none	Increase Score 2	Increase Score 3	Increase Score 1	Increase Score 0-1
Granulomas	none	none	Increase Score 1	Increase Score 3	Increase Score 0-1	Increase Score 0-1

Scores range from 0 to 3, and are based on masked evaluation of sectioned and stained spleen tissue. The presence of Brucella in tissue was confirmed by immunohistochemistry. 0 = normal pathology (all naïve spleens scored 0 in all categories); 1 = mild pathology, 2 = moderate pathology, 3 = severe pathology relative to uninfected (naïve) control.