Immunization with an isolate-common surface protein protects cattle against anaplasmosis

Area of Science:

• Veterinary Medicine
• Parasitology
• Immunology

Background:

• Hemoparasitic diseases, particularly anaplasmosis, are a major threat to global livestock, causing substantial economic losses.
• Anaplasmosis affects cattle in tropical and subtropical regions, leading to significant mortality rates, especially in the United States.
• Current immunoprophylaxis for anaplasmosis remains ineffective, highlighting the need for novel vaccine strategies.

Purpose of the Study:

• To identify a target for an effective immunoprophylaxis against bovine anaplasmosis.
• To investigate a specific surface protein of Anaplasma marginale for its potential in vaccine development.

Main Methods:

• Monoclonal antibody inhibition of infectivity was used to identify a neutralization-sensitive epitope on the Anaplasma marginale 105,000 molecular weight surface protein (Am 105).
• The identified epitope's commonality across multiple Anaplasma marginale isolates with varying characteristics was assessed.
• Cattle were immunized with purified Am 105 and subsequently challenged with virulent Anaplasma marginale to evaluate protection.

Main Results:

• A common, neutralization-sensitive epitope was identified on the Am 105 surface protein of Anaplasma marginale.
• This epitope was present across eight Anaplasma marginale isolates, despite their antigenic, morphologic, and protein structural differences.
• Cattle immunized with Am 105 demonstrated protection when challenged with virulent Anaplasma marginale.

Conclusions:

• The Am 105 protein contains isolate-common epitopes that can induce protective immunity in cattle.
• This finding provides a strong foundation for developing an effective subunit vaccine against bovine anaplasmosis.