Protective Efficacy of Recombinant Turkey Herpes Virus (rHVT-H5) and Inactivated H5N1 Vaccines in Commercial Mulard Ducks against the Highly Pathogenic Avian Influenza (HPAI) H5N1 Clade 2.2.1 Virus

PLoS One. 2016 Jun 15;11(6):e0156747. doi: 10.1371/journal.pone.0156747. eCollection 2016.

Abstract

In Egypt, ducks kept for commercial purposes constitute the second highest poultry population, at 150 million ducks/year. Hence, ducks play an important role in the introduction and transmission of avian influenza (AI) in the Egyptian poultry population. Attempts to control outbreaks include the use of vaccines, which have varying levels of efficacy and failure. To date, the effects of vaccine efficacy has rarely been determined in ducks. In this study, we evaluated the protective efficacy of a live recombinant vector vaccine based on a turkey Herpes Virus (HVT) expressing the H5 gene from a clade 2.2 H5N1 HPAIV strain (A/Swan/Hungary/499/2006) (rHVT-H5) and a bivalent inactivated H5N1 vaccine prepared from clade 2.2.1 and 2.2.1.1 H5N1 seeds in Mulard ducks. A 0.3ml/dose subcutaneous injection of rHVT-H5 vaccine was administered to one-day-old ducklings (D1) and another 0.5ml/dose subcutaneous injection of the inactivated MEFLUVAC was administered at 7 days (D7). Four separate challenge experiments were conducted at Days 21, 28, 35 and 42, in which all the vaccinated ducks were challenged with 106EID50/duck of H5N1 HPAI virus (A/chicken/Egypt/128s/2012(H5N1) (clade 2.2.1) via intranasal inoculation. Maternal-derived antibody regression and post-vaccination antibody immune responses were monitored weekly. Ducks vaccinated at 21, 28, 35 and 42 days with the rHVT-H5 and MEFLUVAC vaccines were protected against mortality (80%, 80%, 90% and 90%) and (50%, 70%, 80% and 90%) respectively, against challenges with the H5N1 HPAI virus. The amount of viral shedding and shedding rates were lower in the rHVT-H5 vaccine groups than in the MEFLUVAC groups only in the first two challenge experiments. However, the non-vaccinated groups shed significantly more of the virus than the vaccinated groups. Both rHVT-H5 and MEFLUVAC provide early protection, and rHVT-H5 vaccine in particular provides protection against HPAI challenge.

MeSH terms

  • Animals
  • Ducks / immunology*
  • Ducks / virology
  • Herpesvirus 1, Meleagrid / immunology*
  • Host-Pathogen Interactions / drug effects
  • Host-Pathogen Interactions / immunology
  • Influenza A Virus, H5N1 Subtype / immunology*
  • Influenza A Virus, H5N1 Subtype / physiology
  • Influenza Vaccines / administration & dosage
  • Influenza Vaccines / immunology*
  • Influenza in Birds / immunology
  • Influenza in Birds / prevention & control
  • Influenza in Birds / virology
  • Poultry Diseases / immunology
  • Poultry Diseases / prevention & control*
  • Poultry Diseases / virology
  • Protective Agents / administration & dosage
  • Time Factors
  • Treatment Outcome
  • Turkeys / virology
  • Vaccination / methods
  • Vaccines, Inactivated / administration & dosage
  • Vaccines, Inactivated / immunology
  • Vaccines, Synthetic / administration & dosage
  • Vaccines, Synthetic / immunology
  • Viral Vaccines / administration & dosage
  • Viral Vaccines / immunology*
  • Virus Shedding / drug effects
  • Virus Shedding / immunology

Substances

  • Influenza Vaccines
  • Protective Agents
  • Vaccines, Inactivated
  • Vaccines, Synthetic
  • Viral Vaccines

Grants and funding

This work was supported by the United States Agency for International Development (USAID) under a grant (AID-263-IO-11-00001, Mod.#3) and within the framework of OSRO/EGY/101/USA, which applies to projects jointly implemented by the FAO, GOVS and NLQP. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.