title: A cocktail of in vitro efficient phages is not a guarantee for in vivo therapeutic results against avian colibacillosis.
abstract: Avian pathogenic Escherichia coli (APEC) causes colibacillosis in poultry, leading to important economic losses worldwide. To cure APEC-infected chickens, a cocktail of four different APEC-specific bacteriophages (phages) was composed and tested. Specific phages were selected from a collection of phages isolated in Belgium. The selection was based on their obligate lytic infection cycle, a broad host range, low cross-resistance and low frequency of development of resistant APEC mutants. Genome analysis of the phages indicated they were close relatives of T4 and N4, considered to be safe in vivo. Chickens were intratracheally infected with APEC strain CH2 (serogroup O78), causing a mortality of about 50% during the seven days following the infection. The phage cocktail was administered 2h after the infection, via three different ways: intratracheally, intra-esophageally or via the drinking water. Treated groups did not show a significant decrease in mortality, lesion scores or weight loss compared to untreated groups, although the APEC-specific phages could be re-isolated from the lung and heart of chickens that were euthanized. Moreover, the re-isolated bacteria from infected chickens had remained sensitive to the phage cocktail. Our results indicate that the efficiency of the phage cocktail used in treating CH2-infected chickens in vivo is negligible, even though in vitro, the phages in the cocktail were able to efficiently lyse the APEC strain CH2. Our results emphasize that the 'traditional' pathway of isolation, followed by phenotypical and genotypical characterization of phages composing the cocktail, does not lead to success in phage therapy in all cases.
authors.affiliation: Structural and Molecular Microbiology, VIB, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Department Structural Biology, VIB, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Viral Genetics Research Group, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Laboratory of Gene Technology, KU Leuven, Kasteelpark Arenberg 21, 3001 Leuven, Belgium. Electronic address: jessica.tsonos@gmail.com.
authors.forename: Jessica
authors.initials: J
authors.lastname: Tsonos
authors.affiliation: Laboratory of Physiology and Immunology of Domestic Animals, KU Leuven, Kasteelpark Arenberg 30, 3001 Leuven, Belgium; Department of General Bacteriology, CODA-CERVA, Groeselenberg 99, 1180 Brussels, Belgium. Electronic address: leon.oosterik@biw.kuleuven.be.
authors.forename: Leon H
authors.initials: LH
authors.lastname: Oosterik
authors.affiliation: Laboratory of Physiology and Immunology of Domestic Animals, KU Leuven, Kasteelpark Arenberg 30, 3001 Leuven, Belgium; Department of Veterinary Microbiology and Parasitology, Sokoine University of Agriculture, P.O. Box 3019, Chuo Kikuu, 67125 Morogoro, Tanzania. Electronic address: hntuntufye@gmail.com.
authors.forename: Huruma N
authors.initials: HN
authors.lastname: Tuntufye
authors.affiliation: Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich, Switzerland. Electronic address: jochen.klumpp@hest.ethz.ch.
authors.forename: Jochen
authors.initials: J
authors.lastname: Klumpp
authors.affiliation: Department of General Bacteriology, CODA-CERVA, Groeselenberg 99, 1180 Brussels, Belgium; Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. Electronic address: Patrick.Butaye@coda-cerva.be.
authors.forename: Patrick
authors.initials: P
authors.lastname: Butaye
authors.affiliation: Structural and Molecular Microbiology, VIB, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Department Structural Biology, VIB, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium. Electronic address: hdegreve@vub.ac.be.
authors.forename: Henri
authors.initials: H
authors.lastname: De Greve
authors.affiliation: Viral Genetics Research Group, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium. Electronic address: jphernal@vub.ac.be.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hernalsteens
authors.affiliation: Laboratory of Gene Technology, KU Leuven, Kasteelpark Arenberg 21, 3001 Leuven, Belgium. Electronic address: rob.lavigne@kuleuven.be.
authors.forename: Rob
authors.initials: R
authors.lastname: Lavigne
authors.affiliation: Laboratory of Physiology and Immunology of Domestic Animals, KU Leuven, Kasteelpark Arenberg 30, 3001 Leuven, Belgium; Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. Electronic address: bruno.goddeeris@kuleuven.be.
authors.forename: Bruno M
authors.initials: BM
authors.lastname: Goddeeris
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001530:Belgium; D001691:Biological Therapy / Q000379:methods / Q000662:veterinary*; D002645:Chickens; D003090:Coliphages; D017931:DNA Primers / Q000235:genetics; D004927:Escherichia coli Infections / Q000628:therapy / Q000662:veterinary*; D046529:Microscopy, Electron, Transmission; D011201:Poultry Diseases / Q000382:microbiology* / Q000628:therapy*; D018709:Statistics, Nonparametric; D016896:Treatment Outcome
chemical_list: D017931:DNA Primers
keywords: Avian pathogenic Escherichia coli; Bacteriophage therapy; Colibacillosis