A Novel Lactococcal Vaccine Expressing a Peptide from the M2 Antigen of H5N2 Highly Pathogenic Avian Influenza A Virus Prolongs Survival of Vaccinated Chickens

A cost-effective and efficacious influenza vaccine for use in commercial poultry farms would help protect against avian influenza outbreaks. Current influenza vaccines for poultry are expensive and subtype specific, and therefore there is an urgent need to develop a universal avian influenza vaccine. We have constructed a live bacterial vaccine against avian influenza by expressing a conserved peptide from the ectodomain of M2 antigen (M2e) on the surface of Lactococcus lactis (LL). Chickens were vaccinated intranasally with the lactococcal vaccine (LL-M2e) or subcutaneously with keyhole-limpet-hemocyanin conjugated M2e (KLHM2e). Vaccinated and nonvaccinated birds were challenged with high pathogenic avian influenza virus A subtype H5N2. Birds vaccinated with LL-M2e or KLH-M2e had median survival times of 5.5 and 6.0 days, respectively, which were significantly longer than non-vaccinated birds (3.5 days). Birds vaccinated subcutaneously with KLH-M2e had a lower mean viral burden than either of the other two groups. However, there was a significant correlation between the time of survival and M2e-specific serum IgG. The results of these trials show that birds in both vaccinated groups had significantly ( < 0.05) higher median survival times than non-vaccinated birds and that this protection could be due to M2e-specific serum IgG

Dogs, Canis familiaris, find hidden food by observing and interacting with a conspecific

Social learning is an important process in the development of behaviour in many species. It is involved in information transfer concerning food that leads, in some species, to food preferences. In our experiment an adult dog (the observer) was allowed to observe another adult dog (the demonstrator) while the latter was disappearing behind one of four projecting blinds. In one trial the demonstrator dog found food behind the projecting blind, but not in the other. After the demonstrator had inspected the potential food location, it returned to the observer dog and they were allowed to interact and to have snout contact. Afterwards, the observer dog was allowed to inspect the potential food locations, while no olfactory cues from the food were given. The observer dogs were able to adjust their search behaviour depending on the knowledge gained by observing and interacting with a conspecific. Food availability to the demonstrator dog during the demonstration phase increased the willingness of observer dogs to have snout contact with their demonstrators and increased their motivation to search for food. In contrast to snout contact, however, food availability to the demonstrator dog had no influence on the decision to go to a particular food location. Furthermore, our results suggest that dogs use snout contact as a source of information to decide whether to go to a potential food location or not

Incentive motivation in pet dogs - preference for constant vs varied food rewards.

Recently, there has been a move towards positive reinforcement using food rewards in animal training. By definition, rewards function as reinforcers if they increase or maintain the frequency of behaviour that they follow. However, in operant conditioning tasks animals frequently show systematic changes in performance - in particular a reduction in responding over time. One suggested strategy to avoid such performance decrements is to provide a variety of food rewards, rather than the same food reward in all trials. The enhancement of appetitive behaviour and consumption by reward variation is referred to as 'variety effect'. We investigated whether dogs preferred a variable or a constant food reward in a concurrent two-choice test. Of 16 dogs, six subjects showed a significant preference for the varied food reward and six for the constant food reward, while four dogs exhibited no significant preference for either option. At the group level, there was a significant effect of block: preference for the varied food reward increased across six blocks of ten trials each. Thus, although some individuals may prefer a single, favourite food reward in the short term, introducing variation in reward types may maintain dogs' motivation in operant tasks over a longer time period