High-throughput sequencing as a potential tool in the quality control of infectious bronchitis vaccines.

Introduction: In Europe, veterinary vaccines are strictly controlled by the Official Medicines Control Laboratories (OMCLs) of the General European OMCL Network, coordinated by the European Directorate for the Quality of Medicines & HealthCare. Despite a meticulous verification programme for immunological veterinary medicinal products (IVMPs), the products' genomic composition has not yet been subject to evaluation in veterinary pharmacy.

Material and methods: A study was carried out on Poland's poultry vaccines containing the infectious bronchitis virus which have the greatest market penetration. Three batches of three different vaccines were high-throughput sequenced and analysed for genomic composition, frequency of variants and the phylogeny of the strains.

Results: The main genetic component of each vaccine was infectious bronchitis coronavirus. The identity of the vaccine strain types was confirmed to be consistent with the manufacturer's declaration (793B, Mass and QX). Most variants were identified for the same nucleotide positions in all three batches of each vaccine, demonstrating the homogeneity of the samples, while unique variants specific to single batches were rare.

Conclusion: High-throughput sequencing (HTS) is an effective alternative poultry IVMP quality control tool for OMCLs. This technique allows in-depth characterisation of a vaccine strain and assessment of its conformance to the manufacturer's declaration. Importantly, HTS brings new cognitive value to IVMP quality control, because it makes monitoring the level of revertants possible. However, before it could be introduced into routine quality control, a thorough analysis and characteristics of the IVMP to be evaluated is needed from the medical product's manufacturer.