Development of improved vaccines for heartwater

Area of Science:

• Veterinary Medicine
• Immunology
• Molecular Biology

Background:

• Heartwater disease poses a significant threat to livestock, particularly in sub-Saharan Africa and the Caribbean.
• Current control methods, including acaricides and live blood vaccines, have limitations such as cost, environmental impact, and disease transmission risks.
• Existing vaccines are laborious, difficult to standardize, and may transmit other pathogens.

Purpose of the Study:

• To develop and evaluate novel vaccine strategies for controlling heartwater disease.
• To address the limitations associated with current heartwater disease management practices.
• To provide effective immunization against Ehrlichia ruminantium, the causative agent of heartwater.

Main Methods:

• Development and laboratory testing of a first-generation inactivated vaccine against Ehrlichia ruminantium.
• Field trials of the inactivated vaccine in cattle, sheep, and goats across four southern African countries.
• Development and evaluation of a second-generation DNA vaccine encoding immunogenic E. ruminantium proteins in mouse models, cattle, and sheep.

Main Results:

• The first-generation inactivated vaccine demonstrated protection against mortality from heartwater challenge in cattle, sheep, and goats.
• The inactivated vaccine can be adapted to include various Ehrlichia ruminantium strains for broader field protection.
• The second-generation DNA vaccine showed efficacy in preclinical and clinical evaluations.

Conclusions:

• Improved vaccines against heartwater disease are crucial for enhancing livestock farming in affected regions.
• These novel vaccines offer a more effective and safer alternative to existing control methods.
• The developed vaccines have the potential to control heartwater spread, including in disease-naïve regions like the United States.