Mucosal immunization with polymeric antigen BLSOmp31 using alternative delivery systems against Brucella ovis in rams

Area of Science:

• Veterinary immunology
• Vaccinology
• Bacterial disease control

Background:

• Brucella ovis causes contagious epididymitis in rams, impacting sheep reproduction.
• Current vaccines have limitations; subcellular vaccines offer an alternative.
• Previous work identified chitosan microspheres (ChMs) and Poloxamer 407-Ch gel for mucosal delivery of BLSOmp31 antigen.

Purpose of the Study:

• To evaluate the immunogenicity and protective efficacy of intranasal and conjunctival immunization with BLSOmp31-ChM and BLSOmp31-P407-Ch against Brucella ovis in rams.

Main Methods:

• Rams were immunized intranasally or conjunctivally with BLSOmp31 formulated in ChMs or Poloxamer 407-Ch gel.
• Humoral (IgG, IgA) and cellular immune responses were assessed.
• Serological diagnostic interference was evaluated.
• Protection was measured by B. ovis excretion in semen and organ colonization.

Main Results:

• Intranasal BLSOmp31-ChM and intranasal/conjunctival BLSOmp31-P407-Ch induced systemic, local, and preputial antibody responses.
• Neither formulation interfered with serological diagnosis.
• Mucosal immunization stimulated specific cellular immunity and prevented B. ovis semen excretion.
• Vaccination did not prevent infection but reduced organ colonization and altered bacterial distribution.

Conclusions:

• Mucosal delivery systems (ChMs and Poloxamer 407-Ch gel) are effective for intranasal and conjunctival vaccination against Brucella ovis.
• These vaccines induce protective immune responses, reducing bacterial shedding and organ burden in rams.
• Further development could lead to improved control strategies for ovine contagious epididymitis.