Immunological response against bovine viral diarrhoea virus (BVDV) types 1 and 2 after vaccination with DIVENCE (R), measured by ELISA and serum neutralisation on serum and milk samples

BackgroundA novel subunit vaccine, DIVENCE(R), comprises different bovine respiratory and reproductive antigens, including BVDV-1 E2 recombinant glycoprotein and BVDV-2 E2 recombinant glycoprotein. This study evaluated the immune response against BVDV-1 and 2 generated by DIVENCE(R) over the long term in different strains. MethodsTwo different studies were conducted to assess the immune response induced by DIVENCE(R). In the first study, 20 seronegative young calves (55-104 days of age) were randomly distributed into the vaccinated or control group. All animals were given four intramuscular doses (D0, D21, D204 and D570) of 2 mL DIVENCE(R) or phosphate-buffered saline (PBS). Blood samples were collected to assess BVDV serum antibodies (ELISA) and neutralising antibodies (SN) against BVDV-1 and BVDV-2. In the second trial, heifers (from 10 months of age until calving) and cows (between first and seventh calving) were included and assigned to the vaccinated and control groups. Three different farms were enrolled in the study. The administration regimen was the same as described in the first study. Blood samples were collected from 32 random animals on each farm (16 vaccinated and 16 control animals). Additionally, bulk tank milk samples from each farm were obtained at different time-points and individual milk samples were obtained from vaccinated and control animals. The immune response against BVDV was analysed in serum and milk samples using different ELISA kits. Neutralising antibodies induced by DIVENCE(R) against different BVDV isolates from Europe and the Americas were also assessed in this trial. ResultsOverall, DIVENCE(R) induced high levels of total antibodies (ELISA) and neutralising antibodies against BVDV-1 and BVDV-2. These values were significantly (p<0.05) greater than the control group from 21 days after the second dose (D42) until the end of the study (D591). The high antibody levels, particularly after the third dose, were similar to those that described efficacy against experimental challenges of BVDV-1 and 2 in pregnant animals. In the field trial, similar results were observed in terms of total antibodies (ELISA) against BVDV, and no induction of anti-p80 antibodies was observed in vaccinated animals at any time. Additionally, analyses on individual and bulk tank milk samples also confirmed that no anti-p80 antibodies were induced in vaccinated animals. Furthermore, high levels of neutralising antibodies were observed against different BVDV isolates from Europe and the Americas. ConclusionThe DIVENCE(R) vaccine induced a strong immune response against BVDV-1 and BVDV-2, and this response allows infected and vaccinated animals to be differentiated (DIVA vaccine).