Banca de DEFESA: NATÁLIA ÉLIDA NASCIMENTO RIBEIRO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : NATÁLIA ÉLIDA NASCIMENTO RIBEIRO
DATE: 27/02/2026
TIME: 14:30
LOCAL: Videoconferência
TITLE:

Isolamento e propagação de Ehrlichia canis (Donatien e Lestoquard, 1935) em linhagens celulares de Ixodes scapularis

KEY WORDS:

Canine ehrlichiosis; tick cells; molecular characterization; genetic diversity; cell culture.

PAGES: 54
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

Canine monocytic ehrlichiosis, caused by Ehrlichia canis, represents an important disease of clinical and epidemiological relevance in tropical and subtropical regions, including Brazil. This study aimed to isolate, propagate, and molecularly characterize E. canis strains obtained from naturally infected dogs in the state of Rio de Janeiro, evaluating diagnostic, biological, and phylogenetic aspects of the isolates. Three dogs with clinical signs compatible with infection by tick-borne agents were analyzed, and their blood samples were submitted to hematological examination, microscopic evaluation, molecular detection by PCR, and isolation in Ixodes scapularis cell lines (IDE8 and ISE6). The observation of intracellular morulae in blood smears allowed for initial screening of the samples, later confirmed by PCR targeting the 16S rDNA, dsb, p28, and trp36 genes. The isolation of three new strains (E.canisPretinha, E.canisLyon, and E.canisScooby) was successful in tick embryonic cells, representing the first in vitro isolation of E. canis in Brazil in the IDE8 cell line and propagation in the ISE6 cell line. Descriptive analysis revealed differences in infection intensity among the strains, with the E.canisPretinha strain showing greater in vitro infectivity. Phylogenetic analyses based on the 16S rDNA and dsb genes demonstrated high genetic conservation, confirming the identity of the samples as E. canis. On the other hand, the p28 and trpi36 genes showed genetic variability among the isolates. Two strains clustered with the American genogroup (TEDSVSAPA), while one strain showed a pattern compatible with the Brazilian genogroup, identified by the ASVVPEAE tandem repeat in the trp36 gene. The findings demonstrate the co-circulation of different genogroups of E. canis in the state of Rio de Janeiro and reinforce the importance of the combined use of conserved and variable molecular markers for diagnosis, isolation, and epidemiological characterization of the agent. Furthermore, the use of cell culture of tick-derived strains proved to be an efficient strategy for isolating new Brazilian strains of E. canis, constituting a promising tool for the development of future investigations focused on genetic diversity, biology, and pathogen-vector interaction.

COMMITTEE MEMBERS:
Presidente - 3247559 - BRUNA DE AZEVEDO BAETA
Interno - ***.781.297-** - CARLOS LUIZ MASSARD - UFRRJ
Externa à Instituição - MARIA TERESA ARMÚA-FERNANDEZ
Externa à Instituição - ANA PAULA MARTINEZ DE ABREU - UV
Externa à Instituição - IZABELA MESQUITA ARAÚJO - UFRRJ