Cross-Neutralization between Bovine Viral Diarrhea Virus (BVDV) Types 1 and 2 after Vaccination with a BVDV-1a Modified-Live-Vaccine.

Control of Bovine Viral Diarrhea Virus types 1 and 2 (BVDV-1 and BVDV-2) involves removing persistently infected animals from the herd, ensuring the biosecurity level of the farms and vaccination for the prevention of fetal infection. Given pestiviruses high genetic and antigenic diversities, one challenge for a BVDV vaccine is to provide the broadest possible heterologous protection against most genotypes and sub-genotypes. The Modified-Live Mucosiffa vaccine, which contains the BVDV-1 sub-genotype 1a (BVDV-1a) cytopathic Oregon C24 strain, was shown to protect fetuses of pregnant heifers against a challenge with a BVDV-1f Han strain. In this study, we tested the cross-neutralizing antibody (NA) response of 9 heifers at 28, 203- and 363-days post-vaccination with Mucosiffa against recent and circulating European strains of BVDV-1a, -1b, -1e, -1f and BVDV-2a. We showed that Mucosiffa vaccination generates a stable over time NA response against all BVDV strains. NA response was greater against BVDV-1a and -1b, with no significant differences between these sub-genotypes. Interestingly the NA response against the two BVDV-2a strains was similar to that observed against the BVDV-1f Han strain, which was the challenge strain used in fetal protection studies to validate the Mucosiffa vaccine. These results suggest that Mucosiffa vaccination provides humoral cross-immunity, which may protect against BVDV-1 and BVDV-2a infection.