Antiparasitic Evaluation of Aquiluscidin, a Cathelicidin Obtained from Crotalus aquilus , and the Vcn-23 Derivative Peptide against Babesia bovis , B. bigemina and B. ovata

Babesiosis is a growing concern due to the increased prevalence of this infectious disease caused by protozoan parasites, affecting various animals and humans. With rising worries over medication side effects and emerging drug resistance, there is a notable shift towards researching babesiacidal agents. Antimicrobial peptides, specifically cathelicidins known for their broad-spectrum activity and immunomodulatory functions, have emerged as potential candidates. Aquiluscidin, a cathelicidin from , and its derivative Vcn-23, have been of interest due to their previously observed antibacterial effects and non-hemolytic activity. This work aimed to characterize the effect of these peptides against three species. Results showed Aquiluscidin's significant antimicrobial effects on species, reducing the . growth rate and exhibiting IC values of 14.48 and 20.70 μM against . and . , respectively. However, its efficacy was impacted by serum presence in culture, and it showed no inhibition against a strain grown in serum-supplemented medium. Conversely, Vcn-23 did not demonstrate babesiacidal activity. In conclusion, Aquiluscidin shows antibabesia activity in vitro and its efficacy is affected by the presence of serum in the culture medium. Nevertheless, this peptide represents a candidate for further investigation of its antiparasitic properties and provides insights into potential alternatives for the treatment of babesiosis.