Advanced Progress in Nanovaccine Technologies for Controlling Poultry Diseases: Development, Efficacy, and Future Prospects

 

Dr. Majed Hamed Al Saegh / poultry pathologist / Australia

 

Introduction

 

The poultry industry faces significant challenges due to infectious diseases, which lead to substantial economic losses and pose a threat to global food security. Although traditional vaccines play a vital role in controlling many of these diseases, they have limitations, such as the need for cold-chain storage, booster doses, and insufficient mucosal immune responses. Hence, nanotechnology has emerged as a promising solution, particularly through the development of nanovaccines designed to improve antigen delivery, enhance immune responses, and provide broad protection.

 

Nanovaccines: Concept and Potential

Nanovaccines utilise nanoparticles (NPs) as carriers and immune adjuvants for antigens. These particles, typically ranging in size from 1 to 300 nanometres, are capable of protecting antigens from degradation, facilitating mucosal delivery, and enabling controlled release. Challenge studies have shown that some of these vaccines can achieve up to 100% protection.

 

Key Nanomaterials in Poultry Nanovaccine Development

• Chitosan Nanoparticles : Chitosan is a natural polymer known for its biocompatibility, mucoadhesive properties, and its ability to stimulate both systemic and mucosal immune responses. It has been used to deliver outer membrane proteins (OMPs) from Salmonella or plasmids encoding viral proteins such as the nucleocapsid protein of Infectious Bronchitis Virus (IBV), resulting in strong immune responses, especially when modified with targeting ligands like mannose.

Discussion: Chitosan is low-cost and available from natural sources (e.g., shrimp shells), but it suffers from poor solubility and potential cytotoxicity at high concentrations. These challenges are being addressed through surface modifications and multi-component formulations.

 

• PLGA Nanoparticles: PLGA is a biodegradable polymer approved by the FDA. It has been used to deliver antigens from Eimeria spp., Newcastle Disease Virus (NDV), and Avian Influenza Virus (AIV), and has shown the ability to stimulate IFN-γ production and activate helper and cytotoxic T cells (CD4+/CD8+), while reducing oocyst shedding.

Discussion: PLGA’s hydrophobic nature limits its use for water-soluble antigens, but surface modification can improve its biocompatibility and cellular targeting.

 

3-  Virus-Like Particles (VLPs) :VLPs structurally resemble viruses but lack genetic material, making them safe and immunogenic. Nanovaccines based on VLPs have been developed to combat H7N9, H5N1, NDV, and IBV, and have shown significant stimulation of both systemic and mucosal immunity.

Discussion: VLPs are highly promising, especially against mutating viruses, but their production requires efficient expression systems such as insect, plant, or yeast cells.

 

4-  Mesoporous Silica Nanoparticles (MSNs) : MSNs offer large surface areas and easily modifiable porous structures. They have been used to deliver antigens from Clostridium perfringens, such as NetB and α-toxin, and have achieved excellent immune responses, particularly when administered orally.

Discussion: Despite their efficacy, their biodegradability and safety need further evaluation under field conditions.

 

5-  Polyanhydride Nanoparticles (PNPs) : These nanoparticles are used to deliver bacterial and viral antigens and have shown strong enhancement of cellular and mucosal immunity, especially when administered orally. They also reduce pathogen shedding.

Discussion: Despite their excellent properties, high production costs and hydrophobic nature limit their widespread use without suitable modifications.

 

6- PVM/MA Nanoparticles : PVM/MA nanoparticles have been used in oral vaccines against Salmonella enteritidis, achieving protection levels comparable to commercial vaccines.

Discussion: These particles need improved stability in aqueous environments, which may be enhanced by using adhesive proteins like BSA or through chemical modification.

 

Immunological and Protective Efficacy

Experiments using various chicken lines (Leghorn, Ross, Cobb, Hy-line) demonstrated high protective efficacy, reaching up to 100% protection. Key immune markers included:

• Increasing IgA and IgG antibody levels
• Increasing Activation of T cells (CD4+/CD8+)
• Increasing Secretion of cytokines such as IFN-γ and IL-4
• Decreasing Viral or bacterial load and shedding

These findings indicate the ability of nanovaccines to reduce infection rates and enhance biosecurity in poultry farms.

 

Challenges and Future Prospects

Despite this progress, challenges remain:

• Limited clinical evidence and large-scale farm application
• Need for long-term safety data
• Complexity and cost of production
• Lack of clear regulatory frameworks in some countries

Future directions include developing multivalent nanovaccines, using plant-based expression systems to reduce cost, and improving oral and mucosal delivery systems to suit the conditions of developing countries.