Specifically, lambs gavaged with 0.023 g OVA persistently for selleck 9 days showed induction of anti-OVA IgG in serum after 4 weeks even without localizing the antigen to a specific region of the gut. If oral tolerance to OVA had been induced, re-exposure to the antigen by intraperitoneal injection should have resulted in a reduction of serum anti-OVA IgG titres after 7 weeks. Instead, we observed that the anti-OVA IgG titres increased relative to what was observed after oral exposure alone (week 4). In fact, average serum titres from lambs gavaged with 0.023 g OVA for 9 days (Average=2.3��10��5+/?1.7��10��5 (StDev) were 1.8 fold higher than was what observed in lambs injected with OVA i.p. without prior oral exposure (Parenteral control group; Average=1.3��10��5+/?1.2��10��5 (StDev)).

Therefore, persistent low dose antigen exposure by the oral route can promote immunity in lambs. However, our experimental design is limited in that it is unclear whether the low dose or duration of exposure (or both) contributed to the immune response. Further studies must be undertaken to clarify the precise dose and duration of exposure required for induction of immunity as well as including direct measurements of mucosal immunity. This knowledge will contribute to our understanding of the underlying mechanisms by which this vaccination strategy promotes immunity. Immunization in the perinatal period should be amenable to current animal husbandry practices as large animals are often segregated from the herd prior to lambing/calving/farrowing and are accessible to producers.

Oral gavage (drenching) is routinely performed by producers without the need for veterinary assistance and oral administration negates the need for needles which reduces risk of carcass condemnation in meat-producing animals. However, we are aware that repeated oral drenching over a period of days is not likely going to be embraced by producers unless the results Carfilzomib are robust enough to warrant this approach, which is not the case with our data. We submit that the results are intriguing enough to warrant further study. Future experiments should include larger numbers of lambs per group to establish how this vaccination strategy affects an out-bred animal population. We intend to study whether a single (or at most two) oral gavage(s) are sufficient to promote immunity if the dose is low (i.e. 0.023 g OVA on the day of birth and/or for 2 days after birth) which is much more likely to be accepted by the livestock industry should the results prove favourable. It is known that the gut of newborn ruminants is semi-permeable for only the first 24�C36 hours after birth to facilitate passive transfer of maternal antibodies from the colostrum [28].