Banca de QUALIFICAÇÃO: TATIANA PÁDUA TAVARES DE FREITAS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : TATIANA PÁDUA TAVARES DE FREITAS
DATE: 29/09/2025
TIME: 09:00
LOCAL: Plataforma Zoom - ONLINE
TITLE:

Occurrence and genetic diversity of Phylum
Apicomplexa hemoparasites in rodents and marsupials in the states of Paraná and Rio de
Janeiro

KEY WORDS:

Small mammals, hemoparasites, 18S Ribosomal DNA

PAGES: 48
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

Protozoa of the Apicomplexa phylum are obligate parasites found in a range of vertebrate and
hematophagous invertebrate hosts, presenting a monoxenous or heteroxenous life cycle,
depending on the parasite, for their complete development. Belonging to the suborder
Adeleorina, apicomplexans of the genus Hepatozoon were first recorded parasitizing small
mammals (rodents and marsupials) in Brazil in the past century. In 1915, Hepatozoon muris
was detected in the rodent Akodon fuliginosus in São Paulo, another species of the parasite was
described as Hemogregarina didelphydis in marsupials of the species Didelphis aurita in Rio
de Janeiro. More recently, a new species named Hepatozoon milleri was described in the rodent
Akodon montensis in São Paulo, using both optical microscopy and molecular analyses. In our
study, liver samples and blood smears were obtained from 309 small non -flying mammals
captured in municipalities in the states of Paraná (Cruz Machado, Lidianópolis and Ponta
Grossa) and Rio de Janeiro (Iguaba Grande and Nova Friburgo), belonging to three species of
didelphid marsupials (Didelphis aurita, Monodelphis americana and Philander quica), 14
species of wild rodents of the Cricetidae family (Akodon cursor, Akodon montensis, Akodon
paranaensis, Delomys sublineatus, Euryoryzomys russatus, Juliomys ossitenuis, Necromys
lasiurus, Nectomys squamipes, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus
nasutus, Oxymycterus quaestor, Sooretamys angouya and Thaptomys nigrita) and two species
of synanthropic rodents of the Muridae family (Mus musculus and Rattus rattus). The smears
were stained using the Giemsa method and the gametocytes were detected using optical
microscopy in 10% (31/309) of the small mammals analyzed (Akodon cursor, Akodon
montensis e Oligoryzomys nigripes). Significant morphometric differences were observed in
measurements of gametocytes from rodents of the genus Akodon. Using conventional PCR, 18S
rDNA fragments of Hepatozoon spp. were amplified in 23.3% (72/309) of rodents (A. cursor,
A. montensis, O. nigripes, Oxymycterus nasutus, Oxymycterus quaestor, Sooretamys angouya
e Mus musculus). No infection by Hepatozoon spp. was detected in the marsupials analyzed in
this study. Phylogenetic analyses demonstrated that the sequences obtained from rodents in this
study (n = 41) grouped into a subclade with other sequences from small mammals in Brazil and
belonged to four different haplotypes. Subsequently, three long sequences (>1600 bp)
representative of haplotypes 1, 3 and 4 were obtained and analyzed. Based on phylogenetic
analysis, this study reinforces the trophic relationship between rodents and reptiles as a possible
transmission cycle of Hepatozoon in South America. Furthermore, our findings expand the
knowledge about the hosts of Hepatozoon spp. by describing Oxymycterus nasutus and
Oxymycterus quaestor as new host species and identifying two new haplotypes circulating in
rodents from the state of Paraná, where the parasite had not yet been detected in animals of this
order.

COMMITTEE MEMBERS:
Interna - 3247559 - BRUNA DE AZEVEDO BAETA
Interno - 3701492 - HUARRISSON AZEVEDO SANTOS
Externa à Instituição - LETÍCIA PEREIRA ÚNGARI - USP
Externa à Instituição - KARINA VARELLA ARPON - FIOCRUZ