A Novel Mucosal Adjuvant System for Immunization against Avian Coronavirus Causing Infectious Bronchitis

Area of Science:

• Veterinary Virology
• Vaccine Technology
• Immunology

Background:

• Infectious bronchitis (IB) poses a significant threat to poultry health, with current vaccines having limitations.
• Modified live virus (MLV) vaccines can revert to virulence, while inactivated and subunit vaccines are weakly immunogenic.
• There is a critical need for more effective and safer IBV vaccines.

Purpose of the Study:

• To evaluate a novel Quil-A and chitosan (QAC) adjuvant system for intranasal delivery of nucleic acid immunogens.
• To improve the protective efficacy of vaccines against infectious bronchitis virus (IBV).

Main Methods:

• Development of a QAC adjuvant system forming nanocarriers for nucleic acid encapsulation and sustained release.
• Encapsulation of plasmid DNA expressing IBV nucleocapsid (N) protein into QAC nanocarriers (pQAC-N).
• Intranasal immunization of chickens with pQAC-N and subsequent challenge with IBV.

Main Results:

• The QAC adjuvant system efficiently encapsulated nucleic acid cargo and demonstrated sustained release.
• pQAC-N vaccination induced robust humoral and cellular immune responses in chickens.
• Immunized birds showed reduced clinical signs and viral shedding post-challenge, comparable to commercial vaccines.

Conclusions:

• The QAC adjuvant system offers a promising platform for developing safer and more effective intranasal vaccines against IBV.
• This technology presents a viable alternative to live vaccines, addressing safety concerns and improving protective efficacy.
• The QAC system has potential applications for other emerging coronaviruses in poultry and beyond.