Banca de DEFESA: Vanessa Sousa Zanardi

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Vanessa Sousa Zanardi
DATE: 31/07/2023
TIME: 09:00
LOCAL: IGM Sala Virtual 5
TITLE:

Histopathological and cellular changes in Biomphalaria glabrata infected by Schistosoma mansoni

KEY WORDS:

hemocytes; immune response; Biomphalaria glabrata; schistosomiasis

PAGES: 124
BIG AREA: Ciências Biológicas
AREA: Parasitologia
SUMMARY:

INTRODUCTION: During the intra-moluscular development of Schistosoma mansoni,
histopathological changes may occur in Biomphalaria glabrata tissue, mainly in the ovotestis
and digestive glands, sites where sporocysts are commonly found. Due to the activity of
hemocytes, cellular alterations may also occur. The characterization of these cells, as well as
the cellular and tissue alterations caused in B. glabrata due to S. mansoni infection, are relevant
for understanding the immunopathogenesis of S. mansoni in B. glabrata. OBJECTIVES:
Describe the morphological and functional changes induced in B. glabrata in S. mansoni
infection. MATERIAL AND METHODS: B. glabrata snails were exposed to 10 miracidia of
S. mansoni. Hemolymph was collected 40, 60 and 80 days after infection. Total and differential
hemocyte counts were performed, as well as cell type characterization. The soft body of these
snails was used for histopathological analysis, using hematoxylin-eosin (HE) and Schiff's
periodic acid (PAS) stains, as well as lectin staining. RESULTS: We observed that S. mansoni
infection causes histopathological changes, compromising the tissue organization of the
ovotestis and digestive gland. In the sites where sporocysts were found, we identified the
presence of hemocytes around them, forming granuloma-like structures. We also observed
impaired carbohydrate reserves in both the ovotestis and digestive gland. We identified six cell
types in the hemolymph of B. glabrata, characterized as blast cells, type I, II and III
hyalinocytes, granulocytes, and "differentiated granulocytes". And we found the total number
of hemocytes was higher in infected snails when observed with uninfected snails differential
hemocyte count also varied between infected and uninfected snails. In uninfected snails the
most frequent hemocytes were blast cells, followed by type I hyalinocytes and granulocytes.
However, in infected snails, depending on the stage of infection, a variation in the most frequent
cell type was observed. Type III hyalinocytes were only observed in infected snails, while type
II hyalinocytes were only found in uninfected snails. Atypical nuclear divisions were also
observed in granulocytes and type I hyalinocytes. CONCLUSIONS: S. mansoni infection leads
to histopathological and cellular changes and interferes with carbohydrate reserves in the
ovotestis and digestive gland. The presence of sporocysts in the ovotestis and digestive gland
was accompanied by the presence of hemocyte infiltrate. We also observed a greater variation
in hemocyte composition in the hemolymph of infected snails compared to uninfected snails.

COMMITTEE MEMBERS:
Externa à Instituição - ESTER MARIA MOTA - Fiocruz - RJ
Externo à Instituição - ARTUR GOMES DIAS LIMA - UNEB
Interno - ***.563.328-** - LEONARDO PAIVA FARIAS - USP
Presidente - 287831 - MITERMAYER GALVAO DOS REIS
Externa à Instituição - SILVANA APARECIDA ROGEL CARVALHO THIENGO - Fiocruz - RJ