Protective Value of Freeze-Dried Inactivated Bovine Viral Respiratory Combined Vaccine Stabilized by Carbomer and Adjuvanted with Saponin

Adjuvants have been used in veterinary vaccines. Carbomer is a synthetic polymer which has a potential vast of applications in the pharmaceuticals. This work aimed to examine the immunologic effect of the carbomer as a stabilizer and adjuvanted with saponin in the lyophilized combined inactivated vaccine (Pneumo-4) instead of regular stabilizers. Freeze-dried vaccine named Pneumo-4 contained the inactivated bovine viral diarrhea virus (BVDV) genotypes, bovine herpesvirus type 1 (BoHV-1), bovine parainfluenza virus type 3 (BPI3V), and bovine respiratory syncytial virus (BRSV). The carbomer 0.3% and 0.5% were used as a stabilizer. The novel stabilizer was compared with 5% lactalbumin hydrolysate with 2.5% sucrose. The saponin solution 1mg saponin/dose was used as an adjuvant and solvent. Twelve local breed calves were utilized in the study. The calves were divided into four groups where each group contained three calves. The first two groups were vaccinated with bovine viral respiratory combined vaccine stabilized by carbomer 0.3% and 05%, respectively. The third group vaccinated with the vaccine stabilized by 5% lactalbumin hydrolysate with 2.5% sucrose. The fourth group was kept without vaccination as a test control. The poster dose was given to the calves of the first three groups 2 weeks post-vaccination. The antibody titer in vaccinated calves was evaluated by the virus neutralization test (VNT). The vaccines showed safety in calves. The immune response against the four viruses got its peak in the 4th month post vaccination. The vaccines stabilized by carbomer showed an appropriate level of protective antibody which lasted until the 9th month post vaccination. There was a very high significance (p≤ 0.05) between the values of neutralizing antibodies between different groups of the experiment. Finally, the use of carbomer as a stabilizer, in addition to saponin as an adjuvant, in the bovine viral respiratory combined vaccine enhances the antibody production in the immunized animals for a time of approximately 9 months. Consequently, the prepared vaccine has a significant economic impact, as it reduces the numbers of vaccination, and thus reduces the costs involved in terms of labor and tools as well as reducing the stress on animals.