Intraperitoneal immunization against necrobacillosis in experimental animals.

Experiments employing recently developed mouse models indicated that intraperitoneal immunization with the cytoplasm (intracellular fraction) of Fusobacterium necrophorum protected the animals from a lethal challenge of the pathogen. The critical immunization schedule needed to achieve complete protection involved six weekly intraperitoneal doses of the intracellular antigen. Livers of immunized mice were cleared of infecting fusobacterial within 24 hours whereas those of nonimmunized mice harboured increasing numbers of hte bacteria. Sera from both groups did not protect recipient mice form developing liver abscesses after challenge. Sheep immunized intraperitoneally with 20 mg of cytoplasmic protein given in three doseases were protected against the development of abscesses induced by F. necrophorum.     

动物疫苗的科学免疫

疫苗是用于预防动物传染病的生物药品,掌握有关购买、运输、保存和使用的正确方法,有助于充分发挥疫苗的功效。本文叙述了动物疫苗的科学免疫方法、使用技术和常见的问题。     

Aerosol immunization against Newcastle disease

The NDV-6-strain was selected by Lomniczi from naturally occurring Newcastle-disease-virus-strains. This strain was administered to chicken of different ages without detrimental effects. The strain was thermoresistant and adapted by serial passages in gut epithelial cells (NDV-6/10 variant). By using an aerosol of this strain (10(7),(3) EID50/m3) more than 1,3 millions chicken were immunised either in the incubator and up to an age of 10 days. Vaccine reactions were not observed. Vaccination against Marek's disease did not interfere with NDV-vaccination efficacy when day-old chicken were vaccinated with the NDV-6/10 aerosol. Obviously, the vaccine elicits a distinct cell-associated immunity. This explains, why chicken exhibiting low hemagglutination inhibition serum-antibody titers were found resistant to challenge infection with velogenic NDV. Immunity of chicken which have been vaccinated within 1 to 8 days post hatch by the NDV-6/10 aerosol vaccine, persisted 6 to 8 weeks and can be extended by revaccination up to onset of laying. The vaccine is now commercially available and designated VITAPEST.     

In vitro function of bovine neutrophils against Actinomyces pyogenes

Factors that influenced the in vitro bactericidal activity of bovine neutrophils against Actinomyces pyogenes were investigated. Neutrophils and serum from 2 clinically normal donor cows were incubated with bacteria for 2 hours. To determine bactericidal activity, colony-forming units were counted after a 48-hour incubation on blood agar plates. Microscopic examination indicated that in the presence of serum, bacteria were cell associated after incubation, whereas when serum was replaced by medium, bacteria were not cell associated. Bactericidal activity of neutrophils was similar whether the sera were heat-treated at 56 C for 30 minutes or were not heated. Heating the serum at 65 C for 30 minutes significantly (P less than 0.001) reduced bactericidal activity. Bactericidal activity decreased (P less than 0.001) as serum concentration (less than 10%) decreased. More than 80% of the bacteria were killed within the 40 minutes of incubation. The opsonizing capacity of serum varied significantly (P less than 0.01) among 12 cows. Similarly, neutrophil bactericidal activity (by cow) was affected significantly (P less than 0.001). Preincubation of serum with A pyogenes significantly (P less than 0.001) reduced the opsonizing ability of the serum. Culture filtrate of A pyogenes was not chemotactic for neutrophils in vitro.