Abstract

Six lytic bacteriophages (JH1-JH6) lytic against O8 ETEC were isolated from 40 individual fecal samples and 30 sewage samples from pig farms in Nanjing, China. Two of the bacteriophages (JH1 and JH2) with icosahedral heads, necks, contractile tails belonged to the Myoviridae family. The other four bacteriophages (JH3, JH4, JH5 and JH6) had relatively thin, long, non-contractile and belonged to the Siphoviridae family. Unlike typicalSiphoviridae family members’ morphologyes had flexible tails, whereas JH5 had the straight tails and fibers. All bacteriophages produced clear plaques in double agar, with JH6 producing the largest plaques. Phages JH1 to JH6 lysed 50 to 100% of 12 O8: F18 ETEC strains, 50 to 75% of 20 O8:F4 ETEC, 5 to 42.5% of 40 non-O8 ETEC and 4.76 to 9.52% of 21 chickens E. coli strains. No lysis of E. coli strain from cows, as well asEscherichia coli in other O serogroups (O2, O5, O9, O11, O138, O139, O141 and O149), was observed. All bacteriophages titers were unaffected by exposure to pH 5 to 9 for 16 h. Sodium dodecyl sulphate-polyacrilamide gel electrophoresis (SDS-PAGE) obtained from proteins was extracted from the various bacteriophages. The proteomes of JH1 and JH2 appear to be identical while that of the other four phages are all different indicating they are probably different. These six bacteriophages are potential candidates for prophylaxis and therapeutic strategies against diarrhea in piglets caused by O8 ETEC.

Key words: O8 serogroup, bacteriophage, enterotoxigenic, Escherichia coli, diarrhea in piglets.