EVALUATION OF THE DYNAMICS OF INFECTION BY Babesia goianiaensis IN CAPYBARAS (Hydrochoerus hydrochaeris) AND ASSOCIATED TICKS (Amblyomma sculptum and Amblyomma dubitatum)

• Grant number: 25/02531-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: September 01, 2025
• End date: February 29, 2028
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Marcelo Bahia Labruna
• Grantee: Warley Vieira de Freitas Paula
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Babesiosis is an emerging hemoparasitosis caused by intraerythrocytic protozoa of the genus Babesia, with a worldwide distribution and significant importance for One Health. Phylogenetic analyses, based on molecular markers, supported the description of a new species of piroplasmid, Babesia goianiaensis nov. sp., in capybaras (Hydrochoerus hydrochaeris) and ticks of the genus Amblyomma (Amblyomma sculptum and Amblyomma dubitatum). B. goianiaensis represents a new clade of Piroplasmida yet to be characterized in terms of biological features, vectors, parasitic specificity, and pathogenicity. Therefore, the aim of this study is to evaluate the dynamics of infection by B. goianiaensis and its pathogenicity in capybaras (H. hydrochaeris) and associated ticks (A. sculptum and A. dubitatum). To form colonies of infected and non-infected ticks with B. goianiaensis, engorged female ticks of A. sculptum and A. dubitatum will be collected from naturally infested capybaras in a region with detected presence of B. goianiaensis. For this experiment, 16 capybaras will be used, initially, 4 capybaras will be infested with larvae: C1 and C3 will be infested with A. sculptum and A. dubitatum infected with B. goianiaensis, respectively, and C2 and C4 will be infested with A. sculptum and A. dubitatum not infected with B. goianiaensis, respectively. Nymphs obtained from the first infestation will be used to infest 4 capybaras: C5 and C7 will be infested with A. sculptum and A. dubitatum infected with B. goianiaensis, respectively, and C6 and C8 will be infested with A. sculptum and A. dubitatum not infected with B. goianiaensis, respectively. Adult ticks obtained from the second infestation will be used to infest 4 capybaras: C9 and C11 will be infested with A. sculptum and A. dubitatum infected with B. goianiaensis, respectively, and C10 and C12 will be infested with A. sculptum and A. dubitatum not infected with B. goianiaensis, respectively. Larvae (F2) obtained from the infestation with adults will be used to infest 4 capybaras, similar to the first infestation. Eggs, larvae, nymphs, adult ticks, and blood samples from capybaras will have their DNA extracted and processed by PCR targeting a 551-bp fragment of the Babesia spp. 18S rRNA gene, to assess the vector competence, transovarial transmission, transstadial persistence, and deleterious effects on the ticks, as well as the pathogenic potential of the B. goianiaensis infection in capybaras through clinical and hematological evaluation of the animals. Samples negative for Babesia PCR will undergo a second PCR targeting the mitochondrial 16S rDNA gene of ticks and the cytB gene of vertebrates (endogenous control) to evaluate the quality of DNA extraction. B. goianiaensis nov. sp. represents a new clade of Piroplasmida that does not include any of the known Babesia species for which genetic data is available. Therefore, understanding the biological cycle and pathogenicity of B. goianiaensis, its possible arthropod vectors, and reservoir and/or hosts is of great importance for both veterinary medicine and public health, since B. goianiaensis has been detected in an environment where capybaras, ticks, cattle, humans, and other animals live in close proximity.