Infectious bursal disease subunit vaccination.

Area of Science:

• Veterinary Virology
• Immunology
• Molecular Biology

Background:

• Infectious bursal disease virus (IBDV) causes significant economic losses in poultry globally.
• The viral protein 2 (VP2) is the primary antigenic protein of IBDV.
• Effective vaccines are crucial for controlling IBDV outbreaks.

Purpose of the Study:

• To express the VP2 gene and its hypervariable region (hvVP2) of IBDV using Pichia pastoris.
• To evaluate the protective efficacy of these expressed proteins against virulent IBDV challenge in chickens.
• To assess the feasibility of using paraffin-embedded tissues as a source for genetic material.

Main Methods:

• Genetic material was extracted from paraffin-embedded IBDV-infected tissue.
• VP2 and hvVP2 genes were expressed in yeast (Pichia pastoris).
• Specific-pathogen-free chickens were vaccinated with expressed proteins and challenged with virulent IBDV.

Main Results:

• VP2 subunit vaccination completely prevented morbidity and mortality post-challenge.
• hvVP2 vaccination resulted in 30% morbidity and mortality.
• Unvaccinated controls showed 90% morbidity and 60% mortality.
• VP2 vaccination provided significantly higher protection against bursal atrophy (P < 0.05).
• Immunohistochemistry confirmed viral replication and bursal damage in all challenged groups.

Conclusions:

• Paraffin-embedded tissue is a viable source for genomic material for protein expression.
• Pichia pastoris-expressed VP2 protein is immunogenic and confers partial protection against IBDV.
• VP2 subunit vaccination protects against clinical signs and death but not infection.