Single-Shot Vaccines against Bovine Respiratory Syncytial Virus (BRSV): Comparative Evaluation of Long-Term Protection after Immunization in the Presence of BRSV-Specific Maternal Antibodies

Valarcher, Jean François; Hägglund, Sara; Näslund, Katarina; Jouneau, Luc; Malmström, Ester; Boulesteix, Olivier; Pinard, Anne; Leguéré, Dany; Deslis, Alain; Gauthier, David; Dubuquoy, Catherine; Pietralunga, Vincent; Rémot, Aude; Falk, Alexander; Shevchenko, Ganna; Bergström Lind, Sara; Von Brömssen, Claudia; Vargmar, Karin; Zhang, Baoshan; Kwong, Peter D.; Rodriguez, María Jose; Garcia Duran, Marga; Schwartz-Cornil, Isabelle; Taylor, Geraldine; Riffault, Sabine

The induction of long-lasting clinical and virological protection is needed for a successful vaccination program against the bovine respiratory syncytial virus (BRSV). In this study, calves with BRSV-specific maternally derived antibodies were vaccinated once, either with (i) a BRSV pre-fusion protein (PreF) and Montanide(TM) ISA61 VG (ISA61, n = 6), (ii) BRSV lacking the SH gene (ΔSHrBRSV, n = 6), (iii) a commercial vaccine (CV, n = 6), or were injected with ISA61 alone (n = 6). All calves were challenged with BRSV 92 days later and were euthanized 13 days post-infection. Based on clinical, pathological, and proteomic data, all vaccines appeared safe. Compared to the controls, PreF induced the most significant clinical and virological protection post-challenge, followed by ΔSHrBRSV and CV, whereas the protection of PreF-vaccinated calves was correlated with BRSV-specific serum immunoglobulin (Ig)G antibody responses 84 days post-vaccination, and the IgG antibody titers of ΔSHrBRSV- and CV-vaccinated calves did not differ from the controls on this day. Nevertheless, strong anamnestic BRSV- and PreF-specific IgG responses occurred in calves vaccinated with either of the vaccines, following a BRSV challenge. In conclusion, PreF and ΔSHrBRSV are two efficient one-shot candidate vaccines. By inducing a protection for at least three months, they could potentially improve the control of BRSV in calves.