Banca de QUALIFICAÇÃO: ENMANUELLA HELGA RATIER TERCEIRO DE MEDEIROS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ENMANUELLA HELGA RATIER TERCEIRO DE MEDEIROS
DATE: 22/10/2024
TIME: 08:30
LOCAL: Sala Virtual Remota (Microsoft TEAMS) https://bit.ly/QualifDoc_EnmanuellaMedeiros_PGBIOEXP
TITLE:

EVALUATION OF THE TRANSCRIPTOME IN Leishmania (Viannia) braziliensis STRAINS IN THE PRESENCE AND ABSENCE OF Leishmania RNA virus 1 AND ITS DIFFERENT in vitro SUSCEPTIBILITY PROFILES TO TRIVALENT ANTIMONIAL.

KEY WORDS:

Gene expression; viral load; phylogeny.

PAGES: 107
BIG AREA: Ciências Biológicas
AREA: Biologia Geral
SUMMARY:

Cutaneous leishmaniasis (CL) is a disease caused by parasites of the genus Leishmania, widely
recorded in tropical and subtropical regions of the world. In Brazil, the incidence is high in the
northern region, with the state of Rondônia reporting approximately 1,000 new cases annually.
The species Leishmania (Viannia) braziliensis is the main one associated with infection cases
in the state and is known to harbor the viral endosymbiont Leishmania RNA virus 1 (LRV1).
The presence of LRV1 has been linked to the development of mucosal lesions in CL and to
cases of treatment failure in patients receiving pentavalent antimonials, whose active form is
trivalent antimonial (SbIII). Preliminary results show different susceptibility profiles of L.
braziliensis strains to SbIII, yet without correlation to the presence and viral load of LRV1. One
of the strategies to understand these conditions in parasite biology was the analysis of molecular
patterns, such as the evaluation of the transcriptome of different strains of L. braziliensis from
the Brazilian Amazon, considering the presence and absence of LRV1 and the susceptibility
profiles presented by the parasite when exposed in vitro to SbIII. For this, 20 strains of L.
braziliensis were selected, 10 of which are positive for LRV1. In these strains, passage recovery
was performed after infection in human monocyte-derived cell lines (THP-1), in order to
minimize variability in gene expression. Following this, growth curves were made for all strains
to determine the logarithmic phase and synchronize the growth stage of the parasites for the
experiments. These strains showed logarithmic phases between 72h and 96h of growth under
the same culture conditions. Consequently, RNA extraction and RNA sequencing (RNA-seq)
were performed. During RNA-seq analyses, four genes were identified: one overexpressed and
three underexpressed between the susceptible vs. less susceptible groups to SbIII. Among the
LRV1+ vs. LRV1- groups, 12 genes were identified, with eight underexpressed and four
overexpressed. These genes are related to metabolic processes, signal transduction, and DNA
recombination and repair. Furthermore, RNA-seq enabled the identification of the first
complete viral genomes from eight strains of L. braziliensis from the Brazilian Amazon, two of
which coinfection with LRV1. Phylogenetic analysis of the LRV1 sequences showed that these
viruses group according to the Leishmania species, reinforcing the hypothesis of coevolution
between Leishmania and LRV1. Therefore, the RNA-seq approach not only allows the
evaluation of differentially expressed genes but also enables the identification of viral
transcripts, potentially serving as an alternative for reanalyzing Leishmania transcriptomes

previously performed to detect the presence of LRV1 and understand the symbiotic parasite-
virus relationship. Given the above, these studies are fundamental for understanding the biology

of Leishmania and its interaction with LRV1, and they may contribute to new strategies for the
prognosis and treatment of CL.

COMMITTEE MEMBERS:
Externo à Instituição - VLADIMIR COSTA SILVA - FIOCRUZ
Presidente - ***.429.088-** - CAROLINA BIONI GARCIA TELES - FIOCRUZ
Externo à Instituição - JOSEPH ALBERT MEDEIROS EVARISTO - FIOCRUZ