PRE-HARVEST INTERVENTIONS FOR APPLICATION DURING POULTRY PRODUCTION TO REDUCE FOOD-BORNE BACTERIAL PATHOGENS
Location: Poultry Microbiological Safety Research
Title: Complete genome sequence of the podoviral bacteriophage CP24R virulent for Clostridium perfringens
Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2011
Publication Date: April 1, 2012
Citation: Morales, C., Oakley, B., Garrish, J.K., Seal, B.S., Siragusa, G.R., Ard, M.B. 2012. Complete genome sequence of the podoviral bacteriophage CP24R virulent for Clostridium perfringens. Archives of Virology. 157:769-772.
Interpretive Summary: Bacteriophages, viruses that infect bacteria, were used therapeutically in Eastern Europe and Russia since the early 1900’s but their use medically was discontinued in Western Europe and the U.S. following discovery of antibiotics. There is resurgent interest in the use of bacteriophages to control pathogenic bacteria due to the development of antibiotic resistant bacteria and the search for other natural product antimicrobials compatible with organic agriculture. Use of bacteriophages or their lytic enzymes to control food-borne and other bacterial pathogens is one approach to reduce these pathogens on farms and in processing facilities. The bacterium Clostridium perfringens can cause human food-borne diseases and causes infectious diseases of humans and animals. Consequently, bacteriophages lytic for C. perfringens were isolated from sewage, feces and broiler chicken intestinal contents. Bacteriophage CP24R was studied because it clearly lysed and killed the host bacterium C. perfringens. The phage was characterized by electron microscopy and whole genome DNA sequencing. Protein sequences of the predicted genes from the phage CP24R genome were compared with those from the databases and putative functions were predicted by significant sequence homology. The bacteriophage genome encoded three lytic enzymes: N-acetylmuramoyl-L-alanine amidase, a lysozyme-endopeptidase, and a zinc carboxypeptidase. These enzymes digest peptidoglycan of the bacterial cell wall and could be potential therapeutics to control C. perfringens.
Bacteriophage 'CP24R was isolated from raw sewage of a waste treatment plant and lytic activity was observed against a type C Clostridium perfringens isolate. Electron microscopy revealed a small virion (44nm diameter icosahedral capsid) with a short, non-contractile tail, indicative of the family Podoviridae. The phage had a linear, double-stranded DNA genome of 18,919 base pairs (bp) with 41 bp inverted terminal repeats and a type B DNA polymerase, which are characteristics of the subfamily Picovirinae. Out of 22 predicted genes in the genome, ten had significant sequence similarity to proteins of known function. Three distinct genes with lytic domains were identified, including a zinc carboxypeptidase domain that has not been previously reported in viruses. The 'CP24R genome described herein is only the second Clostridium perfringens podovirus genome reported to date.