Banca de DEFESA: CARLA ALVES RABELLO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : CARLA ALVES RABELLO
DATE: 28/02/2025
TIME: 09:00
LOCAL: Plataforma Google Meet
TITLE:

Differential expression of immune genes involved in the response ofRhipicephalus microplus (ACARI: IXODIDAE)toTheileria equi(PIROPLASMIDA: THEILERIDAE)infection.

KEY WORDS:

Equine piroplasmosis, Rhipicephalus microplus, pathogen-vector interface

PAGES: 117
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

Theileria equi is an intraerythrocytic protozoan that causes equine piroplasmosis, a disease that affects equids and is responsible for significant health and economic losses to the global equine industry. In Brazil, Rhipicephalus microplus is the only tick species experimentally proven to act as a vector for T. equi. However, the mechanisms involved in this pathogen-vector interaction have not yet been fully elucidated. Therefore, the aim of this study was to analyze the differential expression of genes involved in redox metabolism and the main immune signaling pathways of R. microplus in response to T. equi infection. For this, a chronically infected equine with T. equi (positive control) and a non-infected equine (negative control) were infested with pathogen-free larvae of R. microplus. After the fixation and blood feeding period, whole larvae and nymphs were collected and stored individually, while the females were dissected, and the midgut, ovary, and salivary gland of each specimen were stored separately. RNA was then extracted, and cDNA was synthesized from each sample, followed by relative gene expression assays. In the first chapter, genes related to the redox metabolism of R. microplus in response to T. equi infection were analyzed. A upregulation of both pro-oxidant and antioxidant genes was observed in the midgut and salivary gland of engorged females infected by T. equi, with a particular emphasis on the genes encoding the enzymes dual oxidases (pro-oxidant) and catalase (antioxidant), both being more expressed in the infected group. However, in the salivary gland, the gene encoding the enzyme glutathione-S-transferase was significantly suppressed in the infected group, suggesting that this enzyme may play a key role in the antioxidant response in this tissue. No significant oxidative response was observed in the larval and nymph stages, nor in the ovaries of engorged females. In the second chapter, genes involved in the Toll, IMD, and JAK/STAT immune signaling pathways, as well as genes encoding the antimicrobial peptides microplusin, defensin, and ixodidin, were analyzed. T. equi infection stimulated the activation of the Toll and IMD pathways in the midgut and salivary gland of R. microplus, resulting in a positive regulation of the microplusin and defensin genes in both tissues. However, the JAK/STAT pathway was suppressed in the midgut in response to T. equi infection, which may have led to the non-significant differential expression of the ixodidin gene observed in this tissue. No significant response to T. equi infection through the analyzed pathways was observed in the larval and nymph stages, nor in the ovaries of engorged females. The results obtained in this study provide insights into the molecular mechanisms involved in the interaction between T. equi and R. microplus, contributing to a better understanding of how the tick responds to protozoan infection. Such information aids in identifying key molecules with potential to be used in the development of new strategies for the prevention and control of equine piroplasmosis in the country.

COMMITTEE MEMBERS:
Presidente - 3701492 - HUARRISSON AZEVEDO SANTOS
Interna - 3247559 - BRUNA DE AZEVEDO BAETA
Interna - 2221855 - PATRICIA SILVA GOLO
Externo à Instituição - RODRIGO MACIEL DA COSTA GODINHO - UFRJ
Externo à Instituição - DANIEL DA SILVA GUEDES JUNIOR - FIOCRUZ