Safety of the live Escherichia coli vaccine Poulvac® E. coli in layer parent stock in a field trial
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Safety of the live Escherichia coli vaccine Poulvac® E. coli in layer parent stock in a field trial. / Christensen, Henrik; Nielsen, Christian.
I: Veterinary Microbiology, Bind 240, 108537, 2020.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Safety of the live Escherichia coli vaccine Poulvac® E. coli in layer parent stock in a field trial
AU - Christensen, Henrik
AU - Nielsen, Christian
PY - 2020
Y1 - 2020
N2 - The safety of the live Escherichia coli vaccine Poulvac® E. coli was tested with a flock (10,000) of layer parents aged 30 weeks. Three and 7 days after vaccination, 60 whole unbroken eggs, the egg white and yolk of 60 eggs and 60 cloacal swabs were enriched in MacConkey broth. At both sampling times, 6 out of 60 whole eggs were found positive for coliform bacteria. None of the enriched samples of yolk + egg white were positive for coliform bacteria. Three and seven days after vaccination 44 and 37, respectively out of 60 swabs were positive for coliform bacteria in MacConkey broth. All coliform isolates collected from whole eggs and cloacal swabs were tested in parallel for growth on minimal agar and blood agar to identify the vaccine strain. Some isolates showed reduced growth on minimal agar compared to blood agar and they were tested further with a PCR for the aroA gene mutation and all were found with the wild type version of the gene. Only two isolates did not grow on minimal agar but grew on blood agar and they were tested both with PCR and PFGE. They also showed the wild type version of the aroA gene and their PFGE profile was different from the vaccine strain of Poulvac® E. coli. In conclusion, the Poulvac® E. coli vaccine strain of E. coli was not identified at the detection limit of one CFU on one egg or in the content of one egg or from a cloacal swab of one hen with at least 95 % probability on flock level. The use of the vaccine is safe for hens in lay with lack of survival of the vaccine strain and lack of negative effects on the hens including egg production.
AB - The safety of the live Escherichia coli vaccine Poulvac® E. coli was tested with a flock (10,000) of layer parents aged 30 weeks. Three and 7 days after vaccination, 60 whole unbroken eggs, the egg white and yolk of 60 eggs and 60 cloacal swabs were enriched in MacConkey broth. At both sampling times, 6 out of 60 whole eggs were found positive for coliform bacteria. None of the enriched samples of yolk + egg white were positive for coliform bacteria. Three and seven days after vaccination 44 and 37, respectively out of 60 swabs were positive for coliform bacteria in MacConkey broth. All coliform isolates collected from whole eggs and cloacal swabs were tested in parallel for growth on minimal agar and blood agar to identify the vaccine strain. Some isolates showed reduced growth on minimal agar compared to blood agar and they were tested further with a PCR for the aroA gene mutation and all were found with the wild type version of the gene. Only two isolates did not grow on minimal agar but grew on blood agar and they were tested both with PCR and PFGE. They also showed the wild type version of the aroA gene and their PFGE profile was different from the vaccine strain of Poulvac® E. coli. In conclusion, the Poulvac® E. coli vaccine strain of E. coli was not identified at the detection limit of one CFU on one egg or in the content of one egg or from a cloacal swab of one hen with at least 95 % probability on flock level. The use of the vaccine is safe for hens in lay with lack of survival of the vaccine strain and lack of negative effects on the hens including egg production.
KW - Antibiotic resistance
KW - Chick quality
KW - Escherichia coli
KW - Potential virulence genes
U2 - 10.1016/j.vetmic.2019.108537
DO - 10.1016/j.vetmic.2019.108537
M3 - Journal article
C2 - 31902490
AN - SCOPUS:85076059678
VL - 240
JO - Veterinary Microbiology
JF - Veterinary Microbiology
SN - 0378-1135
M1 - 108537
ER -
ID: 248554949