The present study was undertaken to test the efficacy of a phage cocktail in reducing the levels of colonization by both C. coli and C. jejuni in broiler birds. In order to accomplish this task, experimental models of Campylobacter infection Ku-0059436 research buy were designed and evaluated prior to the in vivo phage experiments. Moreover the best method of administering the phage cocktail was determined in order
to ensure a high and consistent reduction in Campylobacter colonization. A further objective of this study was to evaluate the in vivo acquisition of phage resistance. Results Bacteriophage characterization The phage cocktail used in the present study was composed of three phages (phiCcoIBB35, phiCcoIBB37, phiCcoIBB12) previously isolated from poultry intestinal contents and selected on the basis of their broad lytic spectra against food and clinical C. coli and
C. jejuni strains . The three phages showed different and complementary lytic spectra . They were morphologically, genetically and physiologically characterized by transmission electron microscopy (TEM), pulsed field gel electrophoresis (PFGE), restriction fragment length polymorphism (RFLP) and single-step growth experiments. Morphologically the three phages have a similar structure and size, each possessing an icosahedral head selleck chemicals llc (average diameter of 100 nm) and a contractile tail (140 × 17 nm average length) with tail fibres at the distal end. These morphologies are typical of the Myoviridae family
of lytic phages . Electron micrographs are presented in Figure 1. PFGE and RFLP experiments showed each of the three phages to have a genomic DNA size of approximately 200 kb that was not cut by any of the restriction enzymes tested. Single-step growth curves results (Figure 2) showed that the burst size of phage MAPK Inhibitor Library mouse phiCcoIBB35 was 24 pfu with a latent period of 52.5 min; the burst size of phage phiCcoIBB37 was 9 pfu with a latent period of 67.5 min and the burst size of phage phiCcoIBB12 was 22 pfu with a latent period of 82.5 min. Figure 1 Electron C1GALT1 micrographs of the Campylobacter phages that composed the cocktail: (a) Phage phiCcoIBB12; (b) Phage phiCcoIBB35; (c) Phage phiCcoIBB37. Phages were stained with 1% uranyl acetate and observed with a transmission electron microscopy. There was no difference in morphology between the three phages. They have an icosahedral head of approximately 100 nm in diameter and a contractile tail with 140 × 17 nm average length. This morphology is typical of the members of the Myoviridae family. Figure 2 Single-step growth curve of the Campylobacter phages that composed the cocktail: (a) Phage phiCcoIBB35; (b) Phage phiCcoIBB37; (c) Phage phiCcoIBB12. Single-step growth experiments were performed in order to assess the latent period and burst size of a single round of phage replication: phage phiCcoIBB35 has a burst size of 24 pfu and a latent period of 52.