Analysis of pilin from N. meningitidis C311#3 ChoP biosynthetic mutants. Western blotting of pilin was carried out to investigate the effects of mutations on the presence of ChoP. Pilin was isolated from C311#3 phase variant 5 (lane 1), C311#3 phase variant 6 (lane 2), C311#3 (lane 3), C311#3 betT (lane 4), C311#3 NMB0939 (lane 5), C311#3 pmtA (lane 6), and C311#3 NMB1638 (lane 7). Arrowheads represent the 20.5-kDa molecular mass marker. (a) Western blot with MAb SM1 (specific for class I pili of Neisseria) (41) showing the presence of pilin in all samples. (b) Western blot with MAb TEPC-15 (specific for ChoP) (42) showing the presence of ChoP on pilin in lanes 3 to 7.