Synthetic peptide research demonstrates potential for new bovine vaccine

Bovine babesiosis is a parasitic disease caused by the Babesia bovis species and transmitted by the tick vector Rhipicephalus microplus. When a cow becomes infected with the parasite, clinical signs of disease may present within 7 to 35 days.¹

Photo: Susan Hutton/Adobe Stock

B bovis is associated with severe clinical manifestations, such as hemolytic anemia, hemoglobinuria, and neurological syndrome, all of which result in an overall 5% to 10% mortality rate.^1,2 Subsequent signs of the disease include fever, pale mucous membranes, decreased appetite, reduced milk production, and lethargy.² Because of the nonspecific nature of these symptoms and the potentially dire outcomes, investigators who recently published new research on synthetic vaccines have stressed the importance of new and innovative inoculation development efforts.¹

Farmers and veterinarians have traditionally treated bovine babesiosis with antiparasitic drugs and acaricides.¹ Although the United States eradicated B bovis through years of intensive treatment and control, the parasite is still common in tropical and subtropical regions of the world.^1,2 Consequently, the disease continues to have major health and economic implications for the international cattle industry, according to study authors. Heightened by the rising concerns for drug resistance, high treatment costs, and toxic environmental effects of these antiparasitic therapies and acaricides, experts are emphasizing prophylactic vaccination.¹

Most existing anti-B bovis inoculations are classified as live attenuated vaccines, which utilize a weakened form of the parasite to elicit an immune response. Like various other inoculation types, such as recombinant protein, viral vector, and synthetic peptide, live attenuated vaccines do not provide complete coverage against the parasite because they do not inhibit parasitic invasion of the target cells.¹

To address this issue, researchers have assumed a new functional approach to developing vaccines that instead seeks to identify conserved high activity binding peptides (cHABP) involved in erythrocyte adhesion-invasion. The selected functional peptides are chemically synthesized and tested in a number of assays to determine their viability as vaccine components.1 When used with other parasites from the Apicomplexa phylum, such as Theileria, Plasmodium, and Toxoplasma, this approach has helped to characterize a number of cHABPs that effectively stimulate antibody production in animal models and protect against parasite erythrocyte invasion in vitro.¹

Similar results have been shown in preliminary analyses using B bovis, which produces both B- and T-cell epitopes.1However, the authors highlight the need for continued research on this topic to determine whether Babesia cHABPs will be immunogenic on their own or whether researchers will need to modify or create adjuvants for these protein-derived units.¹

Nonetheless, synthetic peptides show promising results compared to traditional live attenuated vaccines. Among the benefits, the new vaccines demonstrate better stability with fewer adverse effects and are relatively simple and inexpensive to produce with reduced contamination. Additionally, they can be easily reproduced because of the accuracy in characterizing the molecular peptide structures.¹ Given the significant advantages and high potential for efficacy, researchers should continue to implement the functional approach in anti-B bovis vaccine development.

Gabriela Resto is a 2023 PharmD candidate and student of veterinary pharmacy at the University of Connecticut in Storrs.

References

1. Cuy-Chaparro L, Reyes C, Díaz-Guiot EV, Moreno-Pérez DA, Patarroyo MA. Developing anti-Babesia bovis blood stage vaccines: a new perspective regarding synthetic vaccines. Int J Mol Sci. 2023;24(6):5219. doi:10.3390/ijms24065219
2. Spickler, AR. Bovine Babesiosis. Iowa State University Center for Food Security and Public Health. Updated August 2018. Accessed April 12, 2023. cfsph.iastate.edu/diseaseinfo/factsheets/