Challenges in mucosal vaccination of cattle

Area of Science:

• Veterinary Immunology
• Vaccinology
• Infectious Disease Research

Background:

• Mucosal vaccines are crucial for combating infectious diseases entering through mucosal surfaces.
• Oral vaccination in ruminants faces challenges like antigen degradation in the rumen.
• Alternative mucosal delivery methods are being explored for cattle, particularly for respiratory pathogens like Mannheimia haemolytica.

Purpose of the Study:

• To evaluate novel mucosal vaccine strategies for cattle against Mannheimia haemolytica.
• To compare the immunogenicity of orally-delivered and intranasally-delivered vaccines.
• To assess the potential for protection against experimentally induced pneumonia.

Main Methods:

• Calves were vaccinated orally with alfalfa expressing Mannheimia haemolytica antigen or intranasally with ISCOMs containing M. haemolytica antigens.
• Serum and nasal secretions were analyzed for specific antibodies (IgA and IgG) against leukotoxin (Lkt).
• Immunogenicity was compared to a commercial subcutaneous vaccine and experimental challenge models.

Main Results:

• Oral vaccination with antigen-expressing alfalfa increased anti-Lkt IgA in nasal secretions.
• Intranasal vaccination with ISCOMs induced Lkt-specific IgA in nasal secretions.
• Subcutaneous vaccination with ISCOMs induced Lkt-specific IgG in serum and nasal secretions, unlike a commercial vaccine.

Conclusions:

• Both oral and intranasal mucosal vaccination routes can induce specific immune responses in cattle.
• Leveraging rumination for oral delivery or using intranasal ISCOMs are viable strategies.
• Challenges remain in assessing long-term immunogenicity and efficacy against experimental infections.