Establishment of a candidate equine influenza Florida Clade 2 strain A/eq/Richmond/1/07 horse antiserum as Ph. Eur. Biological Reference Preparation/OIE International Reference Reagent.

ABSTRACT

Equine influenza (EI) is an important respiratory disease of horses, with welfare and economic consequences. Vaccination remains one of the most efficient prevention methods available. Equine influenza virus (EIV) is constantly evolving and consequently EI vaccines need to be updated on a regular basis. In 2010, the World Organisation for Animal Health (OIE) Expert Surveillance Panel (ESP) on EI provided a new recommendation for EI vaccine strain composition, including the incorporation of representative EIV strains of both Florida Clade 1 and Clade 2 sub-lineages (FC1 and FC2, respectively). In this context, the European Pharmacopoeia (Ph. Eur.) - OIE reference panel for EI had to be complemented by an antiserum raised in horses against the FC2 representative EIV strain A/eq/Richmond/1/07. An international collaborative study was organised and managed by the European Directorate for the Quality of Medicines and HealthCare (EDQM) within the framework of its Biological Standardisation Programme (BSP). The study aimed at evaluating a new candidate reference for use as a common OIE International Standard/Ph. Eur. Biological Reference Preparation (BRP) horse antiserum to FC2 EIV A/equine/Richmond/1/07. The standard was to be established using the SRH and HI tests for subsequent use in immunogenicity, efficacy and batch potency assay of EI vaccines as a Ph. Eur. BRP (Ph. Eur. monograph 0249) and for use in clinical diagnostic tests as an OIE-approved International Standard Reagent (OIE chapter 3.5.7). The collaborative study confirmed the suitability of the candidate and an SRH titre was assigned. The candidate was adopted as a BRP by the Ph. Eur. Commission and approved by the OIE Biological Standards Commission as an International Standard Serum in November 2017 and February 2018, respectively.