Host tropism determination by convergent evolution of immunological evasion in the Lyme disease system
Fig 1
Lyme borreliae display species-level variation of tickborne transmission to wild-type but not complement-deficient mice and quail.
Ixodes scapularis nymphs infected with B. burgdorferi B31-5A4 (“Bb B31-5A4”), B. garinii ZQ1 (“Bg ZQ1”), or B. afzelii CB43 (“Ba CB43”) fed on (A-C) BALB/c mice, (D-F) C3-/- BALB/c mice, (G-I) Coturnix quail, or (J-L) OmCI-treated Coturnix quail. Uninfected nymphs and mouse and quail tissues were included as control (“Uninfect.”). Fed nymphs were collected upon repletion, and blood and the tick bite sites of skin were collected at 7 days post nymph feeding (“dpf”). Spirochete burdens in (A, D, G, and J) replete nymphs, (B, E, H, and K) tick bite site of skin (“Inoc. site”), and (C, F, I, and L) blood were determined by qPCR. For the burdens in tissue and blood samples, the resulting values were normalized to 100 ng total DNA. Shown are the geometric means of bacterial loads ± 95% confidence interval of bacterial burdens in tissues and blood from 5 mice or quail per group or nymphs feeding on mice (7 nymphs carrying Bb B31-5A4, 6 nymphs carrying Bg ZQ1, or 9 nymphs carrying Ba CB43), C3-/- mice (15 nymphs carrying Bb B31-5A4 or Bg ZQ1, or 13 nymphs carrying Ba CB43), quail (10 nymphs carrying Bb B31-5A4, 13 nymphs carrying Bg ZQ1, or 17 nymphs carrying Ba CB43), or OmCI-treated quail (15 nymphs carrying Bb B31-5A4, 11 nymphs carrying Bg ZQ1, or 15 nymphs carrying Ba CB43). Significant differences (p < 0.05, Kruskal-Wallis test with the two-stage step-up method of Benjamini, Krieger, and Yekutieli) in the spirochete burdens relative to uninfected ticks or tissues are indicated with an asterisk.