The insoluble immune complexes (ICs) were prepared under the conditions of double immunodiffusion in gel, using the suspension of the ultrasound treated PK-15 cell-line infected with porcine parvovirus (PPV) containing both viral particles and viral proteins, as well as pig or rabbit anti-PPV polyclonal immune sera. The immunodiffusion performed in an agarose gel allows only viral subunits with a molecular mass equal to or less than 1000 kDa, rather than the viral particles, to diffuse through the gel and reach the point where the immunoprecipitate is to be formed. The immunoprecipitation under the conditions of the diffusion ensures the optimal, i.e. equimolar ratio of both immunoprecipitating components, antibody/antigen in the IC. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the Western blot analyses showed the ICs were composed of two proteins, a protein in which molecular mass corresponded to the VP2 of the PPV and a protein with a molecular mass of the IgG. This suggests that the ICs are mainly composed of the VP2 antigen and IgG class antibodies. The potency of the IC-vaccines prepared in the form of a water-in-oil-in-water emulsion was compared with that of a commercially available, inactivated oil vaccine. The vaccination of gilts, 6 weeks before mating, with the IC containing allogeneic pig antibodies, resulted in the development of high and long-lasting anti-PPV antibody titres, similar to those generated by the licenced vaccine (P > 0.01). The content of the virus material administered by the IC was twice lower than that in the licenced vaccine. Neither systemic nor local reactions were observed in the gilts during the period of the trial with the IC vaccine. The number of viable piglets per litter varied between 9 and 12 and no signs of the PPV infection were detected. Rabbits were used as one of the alternative laboratory animal models accepted for the testing of the vaccine against the PPV. The rabbit humoral immune response generated by the IC containing the allogeneic antibodies were higher than that generated by the ICs containing the xenogeneic pig antibodies. It was similar to that generated by two-times higher content of the virus material administered by a commercially available vaccine. The IC-based vaccines belong to non-replicating, subunit vaccines, which are both ecologically convenient and the safest vaccines of all.

Commercial chickens with a high level of maternal antibodies for Newcastle disease were vaccinated when newly hatched with Queensland V4 or Ulster 2C Newcastle disease virus (NDV) strains by nebulization. The exposure time to a fine aerosol of vaccine produced with an ultrasonic nebulizer was 60 sec. The chickens were challenged oculonasally with virulent NDV strain Texas GB in weekly intervals up to the 49th day of life. Although protected for several weeks by maternal antibody, they were sufficiently protected thereafter by active immune response to the vaccines. Vaccinal reactions were not observed. Queensland V4 produced higher titers than Ulster 2C and provided better protection to challenge.

The objective of four trials performed on specific-pathogen-free and commercial chickens, either of light or heavy hybrids, was to evaluate the new vaccine delivery method to newly hatched chickens using commercial La Sota vaccine. The vaccine was given by means of nebulization using an ultrasonic device producing homologous aerosol of particles ranging 3-5 microns in diameter. Chickens were exposed to the La Sota vaccine for 30, 60 or 300 s in a closed chamber of the device, thus enabling constant particle size during vaccination. No adverse reaction to the given vaccine was recorded, and the immunity, developed no later than 7 days after vaccination, lasted for at least 49 days which was confirmed by challenge infection using Herts 33 strain of Newcastle disease virus. Maternal antibodies did not influence the development of immunity. Regarding the mode of vaccination, the described method is suitable for the control of Newcastle disease in both big poultry enterprises as well as small backyard flocks when newly hatched chickens are supplied from local hatcheries.

No abstract