FIGURE 2.

The effect and distribution of HN_xs01 on tumor growth and organ colonization following intravenous and intratumoral injections. (A) Mice bearing B16 tumors were injected intravenously with PBS, 2 × 10⁶ CFU/100 μl of E. coli Nissle 1917, or 5 × 10⁷ CFU/100 μl of HN_xs01, respectively. Tumor volume (mm³) and percent of mice weight (%) were measured mice. The antitumor activity of HN_xs01 was similar to that of E. coli Nissle 1917 by intravenous administration. Tumors were significantly inhibited by intravenous injection of HN_xs01. (B) Bacterial distribution in organs was calculated by CFU/g by intravenous administration. Strain HN_xs01 was undetectable in the liver, kidney, and spleen, but small amounts of E. coli Nissle 1917 were detected in other organs compared to the tumor area. (C) Mice bearing B16 tumors were treated by intratumoral injection of PBS or 1 × 10⁸ CFU/100 μl of HN_xs01. Tumors were significantly inhibited by intratumoral injection of HN_xs01. (D) Bacterial distribution in organs was calculated by CFU/g via intratumoral administration. Strain HN_xs01 strictly colonized the tumor region. Data are shown for n = 4 mice per group by intravenous injection and n = 7 mice per group for intratumoral injection.