Heterologous cross-neutralization with different Foot and Mouth Disease vaccine schemes against serotype O strains

BARRIOS-BENITO, MELANIE; MIRAGLIA, M. CRUZ; GALDO-NOVO, SABRINA; TAFFAREL, ANA; BUCAFUSCO, DANILO; CAPOZZO, ALEJANDRA VICTORIA; BORCA, M. V.; PEREZ-FILGUEIRA, DANIEL MARIANO

Kampala

Congreso; 2023 GFRA Scientific Meeting; 2023

Global Foot-and-Mouth Disease Research Alliance (GFRA)

Foot-and-mouth disease (FMD) is a highly infectious disease with potential for rapid spread and severe economic impact. The development of good quality vaccine banks with broad antigenic spectrum coverage is paramount and requires in deep studies to understand how heterologous protection is gained. We have previously shown that increased intra-serotypic cross-protection may be reached for serotype A FMD virus (FMDV) with vaccines including heterotypic strains. Here, we determine the heterotypic cross-reaction using different vaccine schemes against FMDV serotype O strains from different lineages, evaluating the effect of revaccination, different antigen loads, and incorporation of additional FMDV serotypes. Naïve cattle were immunized with seven FMDV vaccines carrying different strain compositions and antigenic payloads. To test the effect of revaccination, each experimental group (n=3) received three immunizations of the same formulation at 0, 28 and 56 days post-primary vaccination (dpv) and serum samples were taken up to 70 dpv. Immune sera were tested by a virusneutralizing test (VNT) against four serotype O FMDV strains from the same topotype as the vaccinal strain (O1/Campos) and other topotypes from East Asia (EA). Starting at the second revaccination, the heterologous neutralizing capacity was improved particularly in vaccines containing the O1/Campos strain, as monovalent (high payload), bivalent o trivalent formulations against most of FMDV strains tested. High payload O1/Campos monovalent vaccines reached high VNT titers (> 2.0 log10) against heterologous strains faster than lower payload formulations. Neutralizing responses against EA region strains (O Taiwan and O SKR 84 ydm) showed high VNT titers after the first revaccination at 28 dpv. Both South American strains obtained during the same outbreaks (O Ecu 46/10 and O Ecu 56/10) showed divergent responses, indicating that even subtle differences in capsid proteins may impact the ability of the immune sera to neutralize the infective FMDV.