FIG. 5.

Transformation of Y. pestis with functional nghA inhibits proventricular biofilm formation but not midgut colonization in fleas. (A) Percentage of fleas that developed proventricular blockage during a 28-day period after infection with Y. pestis (filled squares) or Y. pestis transformed with a high-copy-number (open squares) or low-copy-number (circles) plasmid containing nghA. Horizontal lines indicate means. (B) Flea midgut colonization rates (means ± standard errors of means) from experiments shown in panel A.