Optimum processing conditions for a trivalent-inactivated bovine viral diarrhea virus (BVDV) vaccine using field strains and immunogenicity of candidate formulations with different adjuvants.

Bovine viral diarrhea virus (BVDV) is among the common bovine pathogens worldwide. One of the prominent protection measures of BVDV is vaccination. This study aimed to determine the growth characteristics, inactivation kinetics of vaccine candidates using local BVDV strains [TR-26 (BVDV-1f), TR-21 (BVDV-1l), and TR-15 (BVDV-2b)], and the serological response in experimental animals to inactivated BVDV vaccine formulations prepared with different adjuvants. Optimum MOI values for BVDV strains TR-26, TR-21, and TR-15 were determined as 0.1, 1.0, and 0.01, respectively. In addition, growth curves of TR-26, TR-21, and TR-15 strains were created, and it was determined that they reached the highest titers at 12, 48, and 36 h p.i., respectively. The strains TR-26, TR-21, and TR-15 with titers of 10, 10, and 10 TCID/ml were completely inactivated by 1 mM binary ethyleneimine (BEI) at the 10th, 16th, and 10th hours of treatment, respectively. Guinea pigs were immunized with four vaccine formulations (F1, F2, F3, F4), two with aluminum-based [Al(OH) Al(OH)+Saponin] and two with oil-based (ISA 50 and ISA 206) adjuvants. Neutralization tests were applied to determine the humoral immune response developed after vaccination. Both homologous and heterologous BVDV strains were used for evaluations. Oil adjuvanted vaccines were more efficient to induce antibody titers compared to Al(OH)-based vaccines. In addition, between the oil adjuvanted vaccines, the titers of neutralizing antibodies obtained by Montanide ISA 206 formulation were significantly higher than in Montanide ISA 50 (p < 0.05). Post-vaccinal neutralizing antibodies were detected in the first sampling at 21st day and lasted longer than a 111 days period. The highest antibody response in Guinea pigs was for the strain TR-15. The availability of using BVDV-lf, 1l, and 2b local strains in vaccines and their effectiveness against homologous and heterologous strains have been demonstrated.