Characterization of the diversity of free-living amoebae and giant viruses in the state of São Paulo

• Grant number: 25/11007-3
• Support Opportunities: BIOTA-FAPESP Program - Regular Research Grants
• Start date: November 01, 2025
• End date: October 31, 2028
• Field of knowledge: Biological Sciences - Parasitology - Protozoology of Parasites
• Principal Investigator: Otavio Henrique Thiemann
• Grantee: Otavio Henrique Thiemann
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• City of the host institution: São Carlos
• Associated researchers: Jonatas Santos Abrahao ; Milene Ferro ; Vania Silvia Rosolen

Abstract

Naegleria, Acanthamoeba, Sappinia and Balamuthia are genera belonging to the Free-Living Amoeba (FLA), which comprise a diverse group of amoeboid protozoa present in natural environments, such as soil and water, independent of a host organism to complete their life cycle. FLA belong to different taxonomic groups, mainly within the supergroups Amoebozoa and Excavata, and have common characteristics such as locomotion and feeding using pseudopods. They usually alternate between an active feeding stage (trophozoite) and a dormant and resistant stage (cyst). Although they are generally not parasitic, some species, Naegleria fowleri, Acanthamoeba spp. and Balamuthia mandrillaris for example, can cause serious infections in humans and animals. Despite recent advances, little is known about the biodiversity of FLA in Brazil. Since 2003, the existence of giant viruses has been identified in Acanthamoeba sp., belonging to the phylum Nucleocytoviricota. These viruses replicate in Viral Factories (VF) in the cytoplasm of A. castellanii and encode more than 1,000 genes, involved in several biological processes. Giant viruses arouse great interest due to their diversity, biochemistry and evolutionary origin. This project proposal presents two related strands, the characterization of the diversity of FLAs and giant viruses. The main actions of the proposal are: a) to broaden and deepen the investigation of the diversity of AVLs in flooded environments, expanding the previous project (FAPESP 2018/20693-4); b) to characterize the diversity of Nucleocytoviricota in these environments and identify new representatives of this phylum; c) to develop new molecular markers for the identification of amoeba genera in environmental samples by Metabarcoding. This proposal is in line with the BIOTA-FAPESP program to assess microbial and viral biodiversity, also contributing with important information for public health on the diversity and prevalence of pathogenic amoeba species. (AU)