Efficacy of a Salmonella live vaccine for turkeys in different age groups and antibody response of vaccinated and non-vaccinated turkeys

BMC Research Notes, Jul 2018

Objective Human Salmonellosis continues to be one of the most important foodborne zoonoses worldwide, although a decrease in case numbers has been noted in recent years. It is a foodborne zoonotic infection most commonly associated with the consumption of raw egg products but also with meat consumption including the consumption of poultry products. Turkey flocks in Europe have been reported to be affected by Salmonella infection, too. The present study examines the efficacy of a newly licensed Salmonella life vaccine in reducing infections with the Salmonella serovars Typhimurium and Enteritidis in turkeys. Turkeys were vaccinated the first day of life and at the age of 6 and 16 weeks. Groups of birds which had received different numbers of vaccinations were then submitted to challenge trials with either SE or ST. Results In vaccinated birds Salmonella counts in liver and spleen and, less effectively, in caecum were reduced compared to unvaccinated birds. In several groups serum antibody-titers were statistically significantly higher in vaccinated turkeys than in non-vaccinated ones at day seven post infection, but only in one out of six groups at day 14 post infection.

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Efficacy of a Salmonella live vaccine for turkeys in different age groups and antibody response of vaccinated and non-vaccinated turkeys

Hesse et al. BMC Res Notes Efficacy of a Salmonella live vaccine for turkeys in different age groups and antibody response of vaccinated and non-vaccinated turkeys Martina Hesse 0 Andreas Stamm 0 Rita Weber 0 Gerhard Glünder 0 0 Clinic for Poultry, University of Veterinary Medicine Hannover , Bünteweg 17, Hannover , Germany Objective: Human Salmonellosis continues to be one of the most important foodborne zoonoses worldwide, although a decrease in case numbers has been noted in recent years. It is a foodborne zoonotic infection most commonly associated with the consumption of raw egg products but also with meat consumption including the consumption of poultry products. Turkey flocks in Europe have been reported to be affected by Salmonella infection, too. The present study examines the efficacy of a newly licensed Salmonella life vaccine in reducing infections with the Salmonella serovars Typhimurium and Enteritidis in turkeys. Turkeys were vaccinated the first day of life and at the age of 6 and 16 weeks. Groups of birds which had received different numbers of vaccinations were then submitted to challenge trials with either SE or ST. Results: In vaccinated birds Salmonella counts in liver and spleen and, less effectively, in caecum were reduced compared to unvaccinated birds. In several groups serum antibody-titers were statistically significantly higher in vaccinated turkeys than in non-vaccinated ones at day seven post infection, but only in one out of six groups at day 14 post infection. Salmonella; Turkey; Immunization; Antibody response Introduction Non-host-adapted Salmonellae usually colonize the digestive tract of turkeys asymptomatically [ 1, 2 ]. Although in case of stress or at a very young age turkeys may develop severe clinical signs [1], the most important problem resulting from Salmonella infections lies in the transmission to humans. The main source of food-borne Salmonella outbreaks is the consumption of table eggs and egg products, but single samples of fresh turkey meat yielded the highest proportion of Salmonella-positive results [ 3, 4 ]. Control strategies focus on hygiene and management but also include vaccination [ 5, 6 ]. Despite a recent decrease of the prevalence of human Salmonellosis in several European countries it is still one of the most important food borne zoonoses in Europe [ 7, 8 ]. Vaccination of turkeys might help to reduce prevalence in turkey flocks and transmission to humans further. Barrow et al. [9] stress that the use of vaccines has been empirical and that immunological studies about Salmonella infections in turkeys are still scarce, although certain aspects of the humoral immune response have been studied before [ 10–12 ]. In two recent studies we examined a bivalent live Salmonella vaccine for its ability to induce primary immune reactions after vaccination of 1  day old turkeys [ 13 ] and for its protective efficacy in turkey poults against Salmonella challenge infections at the age of 3  weeks [ 14 ].The latter study found lower Samonella counts in liver, spleen and caecum of vaccinated turkey poults compared to unvaccinated poults in challenge trials at 3 weeks of age. No domination of either a TH1-response or a TH2-response could be determined and no statistically significant difference regarding the IgG serum antibody response between vaccinated and non-vaccinated turkeys after challenge infection was found. The aim of the present study was to examine the protective effect of the mentioned vaccine against Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) infections in turkeys in additional age groups and after a different number of vaccinations. The efficacy was determined by comparing bacterial counts in caeca, liver and spleen after challenge. Since it has been shown that turkeys do not produce antibodies from hatch it should also be determined if birds which were older than the birds in our former studies or which were vaccinated more often would produce a notable serum antibody-response. Main text Materials and methods Experimental design At day of hatch 320 turkeys were housed separately and divided randomly into two groups of 160 birds each. One group served as non-vaccinated control group whereas the other group was directly vaccinated with the Salmonella live vaccine. Booster immunizations were applied at the age of 6 and 16  weeks (Table  1). At 2, 6, 16 and 23  weeks of age challenge experiments were conducted (Table  1). For each challenge experiment 20 vaccinated and 20 non-vaccinated birds were infected with the virulent SE strain and 20 vaccinated and 20 non-vaccinated birds were infected with the virulent ST strain. At day 7 and 14 post infection 10 individuals per group were sacrificed by exsanguination after they had been stupefied by manually applied blunt force trauma and samples were collected. For vaccinated birds which were infected with SE at 6  weeks of age only serum samples d day of life, w w (...truncated)


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Martina Hesse, Andreas Stamm, Rita Weber, Gerhard Glünder. Efficacy of a Salmonella live vaccine for turkeys in different age groups and antibody response of vaccinated and non-vaccinated turkeys, BMC Research Notes, 2018, pp. 431, Volume 11, Issue 1, DOI: 10.1186/s13104-018-3524-1