Fig. 4.
Interstrain dynamics are determined by T6S antagonism in vitro and in vivo. (A) B. fragilis 3986 T(B)9 (BfTB9) is resistant to B. fragilisN (BfN) T6S in vitro. (B) B. fragilisTB9 T6S immunity homologs are functional. Expression of B. fragilisN or B. fragilisTB9 bti2ab homologs confers immunity to a B. fragilisN tssC mutant lacking its own E/I pairs. (C and D) Interactions between B. fragilisN (BfN) and B. fragilis ATCC 43859 (BfA) are determined by T6S in vitro (C) and in vivo (D). For all in vitro experiments: *P < 0.05. Error bars indicate ± SD (n = 2; representative of three independent trials). For D, *P < 0.05 between recipient populations in each group (n = 5 mice per group; representative of two independent trials). Error bars indicate ± SD.