Abstract

Vaccine batches must pass routine quality control to confirm that their ability to induce protection against disease is consistent with batches of proven efficacy from development studies. For poultry vaccines, these tests are often performed in laboratory chickens by vaccination-challenge trials or serological assays. The aim of this study was to investigate innate immune responses against inactivated poultry vaccines and identify candidate immune parameters for in vitro quality tests as alternatives for animal-based quality tests. For this purpose, we set up assays to measure nitric oxide production and phagocytosis by the macrophage-like cell line HD11, upon stimulation with inactivated poultry vaccines for infectious bronchitis virus (IBV), Newcastle disease virus (NDV), and egg drop syndrome virus (EDSV). In both assays, macrophages became activated after stimulation with various toll-like receptor agonists. Inactivated poultry vaccines stimulated HD11 cells to produce nitric oxide due to the presence of mineral oil adjuvant. Moreover, inactivated poultry vaccines were found to enhance Fc receptor-mediated phagocytosis due to the presence of allantoic fluid in the vaccine antigen preparations. We showed that inactivated poultry vaccines stimulated nitric oxide production and Fc receptor-mediated phagocytosis by chicken macrophages. Similar to antigen quantification methods, the cell-based assays described here can be used for future assessment of vaccine batch-to-batch consistency. The ability of the assays to determine the immunopotentiating properties of inactivated poultry vaccines provides an additional step in the replacement of current in vivo batch-release quality tests.

Highlights

  • Infectious diseases are a major problem for the poultry industry and lead to economic losses.vaccination is essential to prevent disease outbreaks and maintain flock health

  • HD11 cells with dose ranges of inactivated infectious bronchitis virus (IBV) and Newcastle disease virus (NDV) antigens provided by different companies did not result in nitric oxide production (Figure 1b)

  • Nitric oxide production was not significantly different from unstimulated HD11 cells when non-emulsified mineral oil was added to the HD11 cells

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Summary

Introduction

Infectious diseases are a major problem for the poultry industry and lead to economic losses.vaccination is essential to prevent disease outbreaks and maintain flock health. Before the first laying period, layers receive several booster vaccinations to maintain this protective immunity during their egg production phase. These may include inactivated multivalent vaccines against a combination of pathogens, such as infectious bronchitis virus (IBV), Vaccines 2020, 8, 332; doi:10.3390/vaccines8020332 www.mdpi.com/journal/vaccines. Since vaccines are complex biological products, each batch requires routine quality control (QC) testing to ensure that it meets the established requirements to induce protection against disease. For many infectious diseases of poultry, the correlates of protection are still unknown and serological assays may not always be the best method to monitor vaccine potency

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