TABLE 1.

Pilin antigenic variation frequencies of Mc8013 strains

Growth (CFU/colony)a	Antigenic variation frequency (%)b of strain:
	Mc8013	recA	recX	recQ	rep	recJ
107c	1.39	NDd	0.22	0.04	ND	ND
108e	2.74	0.02	0.54	0.12	0.01	0.03

^aStrains were grown on solid medium.

^bAntigenic variation frequency was calculated by the number of pilE variant reads divided by the total read number of each strain. All mutants were statistically different from Mc8013 parental strain (P < 0.05) using the two-tailed test of population proportion.

^cMc8013 and recQ strains were grown for 11 h, recX and recJ strains were grown for 13 h, and the recA and rep strains were grown for 15 h.

^dND, no variant reads detected.

^eMc8013 and rep strains were grown for 17 h, and recA, recQ, recX, and recJ strains were grown for 21 h.