Post-vaccination serology in support of FMD vaccine development for Eastern Africa

This document outlines the serological assays offered in support of FMD vaccine development and evaluation with specific reference to Eastern Africa. These services are seen as relevant to the developers or evaluators of vaccines intended for use against the four major serotypes of FMD circulating in Eastern Africa (serotypes O, A, SAT1 and SAT2). The level of post-vaccination virus neutralisation titres (VNT) against heterologous viruses is considered an important indicator of likelihood to protect against disease.

The WRLFMD is assembling such a panel of representative viruses, of the 4 serotypes, after consultation process involving the members of the WOAH/FAO Reference Laboratory Network, AU-PANVAC, and the Eastern African regional laboratory network (EARLN-FMD). Developers or evaluators of FMD vaccines may request VNT to be performed against the panel of isolates by submitting appropriate bovine vaccine sera to the WRLFMD as set out below (additional testing can also be carried out upon request).

East Africa Panel: guidance for submission of bovine sera for post-vaccination assessment at WRLFMD

• The vaccinal serum should be produced in cattle, which have had no previous exposure to FMD virus through vaccination and/or infection and do not have maternal FMDV antibodies.
• The vaccine used should be the product that will be used in the field (i.e. it should be formulated in the same way, have the same potency and contain the same strains as the final formulated vaccine). NB: It is anticipated that the sera submitted for testing may be polyvalent.
• The vaccination regime adopted should be identical to the schedule recommended to customers for use in field situations. Therefore, a booster vaccination may be given if this is part of the recommended primary course
• Sera should be collected from each animal, at the point of vaccination (day 0) and then at day 21 after vaccination. If a second vaccination is given, then serum should also be collected 10 days later.
• Sera from at least five individual cattle should be submitted. These sera should not be pooled

Testing performed at WRLFMD

• Unless advised, all samples (at all time points) will be tested individually by both virus neutralisation test (VNT) and NSP ELISA.
• For the VNT, the sera will be tested against East African FMD virus isolates representing relevant lineages that are circulating in East Africa.
• All results will be reported on individual sera basis.
• Results will be sent back to the submitter confidentially.

The serum will be evaluated against the following criteria

1. Non-structural protein-specific antibodies will be measured using the PrioCHECK FMDV NS Antibody ELISA kit by ThermoFisher Scientific. All pre and post vaccination sera should score negative.
2. Virus Neutralisation Titres will be calculated according to the protocol used at WRLFMD (ISO/IEC 17025 accredited SAU-SOP-4). This SOP follows the method described by the OIE Terrestrial Manual 2018, Chapter 3.1.8 – Foot and mouth disease (infection with foot and mouth disease virus). For each isolate used, the strain-specific neutralisation antibody titres will be calculated using the Kaerber equation (Kaerber, 1931), which calculates the neutralisation titre at a virus dose of 100 TCID₅₀.

Reference

Kaerber G. (1931). Beitrag zur kollektiven behandlung pharmakologischer reihenversuche. Archive fuer Experimentelle Pathologie Pharmakologie, 162, 480-483. DOI: 10.1007/BF01863914read online

Costs of testing sera raised against vaccines with the FMDV Reference Antigen Panel from WRLFMD, Pirbright Institute, UK.

The following information outlines the costs, provided by WRLFMD, associated with the independent testing supplied by WRLFMD:

# USD subject to exchange rate​

Further information about these Reference FMDV antigens (including process to access this panel from WRLFMD) can be found here.