FIG 4.

Immunization with CspZ-YA prevented LD-associated arthritis after exposure to ticks carrying multiple Lyme borrelia strains. Five C3H/HeN mice were vaccinated with CspZ-YA or inoculated with PBS and subsequently infected by nymphal ticks carrying B. burgdorferi strain 297 or B. afzelii strain VS461-JL. Uninfected nymphs were placed on an additional five mice inoculated with PBS as a negative control (N.A.). Tibiotarsus joints were collected from these mice at 21 dpf. To assess inflammation, tissues were fixed and stained with hematoxylin and eosin. (a) Representative images from one mouse per group are shown. Top panels are lower-resolution images (joint, ×10 magnification [bar, 160 μm]); bottom panels are higher-resolution images (joint, ×20 magnification [bar, 80 μm]) of selected areas (highlighted in top panels). Arrows indicate infiltration of immune cells. (b) To quantitate inflammation of joint tissues, at least 10 random sections of tibiotarsus joints from each mouse were scored on a scale of 0 to 3 for the severity of arthritis. Data shown are the mean inflammation score ± standard deviation of the arthritis scores from each group of mice. Asterisks indicate the statistical significance (P < 0.05, Kruskal-Wallis test with Dunn’s multiple comparisons) of differences in inflammation relative to that of uninfected mice.