FMD vaccine matching: inter laboratory study for improved understanding of r1 values

WILLEMS, TOM; ANNEBEL DE VLEESCHAUWER; PEREZ FILGUEIRA, DANIEL; YANMIN LI; BERND HASS; MATTION, NORA; KRIS DE CLERCQ

JOURNAL OF VIROLOGICAL METHODS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2020 vol. 276

0166-0934

Foot-and-mouth disease virus (FMDV) is a highly variable RNA virus existing as sevendifferent serotypes. The antigenic variability between and within serotypes can limit the crossreactivityand therefore the in vivo cross-protection of vaccines. Selection of appropriatevaccine strains is crucial in the control of FMD. Determination of indirect relationships (r1-value) between potential vaccine strains and field strains based on antibody responses againstboth are routinely used for vaccine matching purposes. Aiming at the investigation of therepeatability, reproducibility and comparability of r1-value determination within and betweenlaboratories and serological tests, a small scale vaccine matching ring test for FMDV serotypeA was organized. Well-characterized serum pools from cattle vaccinated with a monovalentA24/Cruzeiro/Brazil/55 (A24) FMD vaccine with known in vivo protection status(homologous and heterologous) were distributed to four laboratories to determine r1-valuesfor the heterologous FMD strains A81/Argentina/87, A/Argentina/2000 andA/Argentina/2001 using the virus neutralization tests (VNT) and liquid phase blocking ELISA(LPBE). Within laboratories, the repeatability of r1-value determination was high for bothantibody assays. VNT resulted in reproducible and comparable r1-values between laboratories,indicative of a lack of antigenic relatedness between the A24 strain and the heterologousstrains tested in this work, thus corresponding to some of the in vivo findings with thesestrains. Using LPBE, similar trends in r1-values were observed in all laboratories, but theoverall reproducibility was lower than with VNT. Inconsistencies between laboratories may atleast in part be attributed to differences in LPBE protocols as well as the in preexistinginformation generated in each laboratory (such as antibody titer-protection correlationcurves). To gain more insight in the LPBE-derived r1-values standard bovine control serawere included in the antibody assays performed in each laboratory and a standardizationexercise was performed.