Response to a Salmonella Enteritidis challenge in old laying hens with different vaccination histories

Abstract

Extending the laying period of laying hens is beneficial for economic and sustainability purposes. Because vaccines were designed with a shorter laying period envisaged, it is unclear whether current Salmonella vaccines can provide sufficient levels of protection against infection at an older age. The purpose of this experiment was to determine the efficacy of early rearing vaccination schemes against Salmonella challenge late in the laying period. There were four treatment groups: birds that had not been vaccinated (Group 1), birds vaccinated with live Salmonella Enteritidis (SE) (Group 2), with live and inactivated SE (Group 3), or with live SE and live Salmonella Typhimurium (Group 4). At the end of the laying period, the birds were transported from the laying farm to the research facility where they were orally challenged with 2.06 × 109 colony-forming units SE at around 82 wk of age. Hens were euthanized and bacteriology was performed on cecum, liver, spleen, and follicular fluid samples to determine SE colonization 7 and 14 d after challenge. Clinical and bacteriological findings of hens vaccinated with different vaccination schemes and the non-vaccinated control group were compared. No significant differences in SE colonization were found for vaccinated groups compared to the non-vaccinated control group. This may be a result of waning immunity due to the long time between vaccination and challenge. Also, as vaccination took place in the rearing period in the field, initial levels of immunity may not have been optimal due to shortcomings in the vaccination technique. Furthermore, the results of this study may have been affected by differences in age, breed, and origin between the groups. Therefore, controlled studies from early age onwards are necessary for more accurate comparisons between vaccines.

A detailed analysis of innate and adaptive immune responsiveness upon infection with Salmonella enterica serotype Enteritidis in young broiler chickens

“…Seven-day-old broiler chickens were successfully infected with SE as was demonstrated by the detection of SE-induced T cell proliferation and SE-specific antibodies from 2–3 weeks after infection. Presence of SE was detected in ileum only at day 7 post-infection and in spleen from day 7 onwards and most likely, the number of bacteria in these tissues were below the detection limit during the first week post-infection as observed previously [ 43 ]. In the first week post-infection, significant increases in numbers of intraepithelial cytotoxic T cells and splenic macrophages were observed in SE-infected compared to uninfected chickens.…”

“…The Salmonella enterica serotype Enteritidis strain (K285/93 Nal res ) was kindly provided by Dr E. Broens, director of the Veterinary Microbiological Diagnostic Center (VMDC) of the Faculty of Veterinary Medicine, Utrecht University, and cultured as described previously [ 43 ]. In short, from an overnight culture of the SE strain on blood agar (Oxoid, the Netherlands) a single colony was used to inoculate 45 mL BHI medium (Oxoid), which was incubated aerobically overnight at 200 rpm in a shaking incubator (Certomat BS-1, B. Braun Biotech international, Sweden) at 37 °C.…”

Contribution of innate and adaptive immune cells to the elimination ofSalmonella entericaserotype Enteritidis infection in young broiler chickens

“…In the current study we aimed to provide a detailed analysis of SE-related innate and adaptive Although SE was demonstrated in ileum and spleen of infected chickens, the presence of the bacteria did not affect growth nor induced severe disease symptoms similar to previous studies in layer chickens [13,34] and young broiler chickens [32,52]. The absence of severe disease symptoms is related to the SE-dose, which was chosen to avoid welfare issues in the chickens.…”

“…The Salmonella enterica serotype Enteritidis strain (K285/93 Nal res ) was kindly provided by Dr. E. Broens, director of the Veterinary Microbiological Diagnostic Center (VMDC) of the Faculty of Veterinary Medicine, Utrecht University, and cultured as described previously [34]. In short, from an overnight culture of the SE strain on blood agar (Oxoid, the Netherlands) a single colony was used to inoculate 45 ml BHI medium (Oxoid), which was incubated aerobically overnight at 200 rpm in a shaking incubator at 37°C.…”

“…The Salmonella enterica serotype Enteritidis strain (K285/93 Nal res ) was kindly provided by Dr. E. Broens, director of the Veterinary Microbiological Diagnostic Center (VMDC) of the Faculty of Veterinary Medicine, Utrecht University, and cultured as described previously [34].…”