Evaluation of the virulence of Acanthamoeba isolates from clinical and environmental samples.
Name: DÉBORA DA VITÓRIA FERREIRA DE MELO
Publication date: 23/03/2018
Advisor:
Name |
Role |
|---|---|
| ALOÍSIO FALQUETO | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| ALOÍSIO FALQUETO | Advisor * |
| BLIMA FUX | Internal Examiner * |
| GUSTAVO ROCHA LEITE | External Examiner * |
Summary: The genus Acanthamoeba comprises protozoa that are widely distributed in diverse
environments and across all continents and that are capable of causing infections in
humans, such as keratitis and granulomatous encephalitis. The pathogenesis of
Acanthamoeba constitutes a multifactorial process, with factors that involve both
ameba and host, but this mechanism of pathogenicity is not yet fully elucidated.
There is little standardization in the methodologies applied here, with variable
protocols in the literature. The objective of this work was to identify the virulence
variations of six isolates of Acanthamoeba, from clinical and environmental
backgrounds, with three different genotypes, T3, T4 and T5 - representing the 20
types of findings, and with two doses of amoebae on three types different from
mammalian cell lines, MDCK, VERO and CHO, using cytotoxic effect and cytotoxic
effect methodologies. Clinical samples are obtained from cultured corneal scrapings
of patients diagnosed with amoebic keratitis, and as environmental samples are
obtained from faucet outlet, flood water and dust, collected and axenized between
the years 2014 and 2017. Considering that prolonged cultivation of Acanthamoeba
isolates may cause a decrease or loss of virulence of the amoeba, we use the
passage of the amebae in MDCK cell line to reactivate the virulence of the isolates in
prolonged culture. Our data demonstrated that a cell line more susceptible to
conditioned medium (cytotoxic effect) was MDCK, followed by VERO and CHO.
However, for the cytopathogenicity assay, CHO was one more susceptible to
exposure to Acanthamoeba trophozoites, followed VERO and MDCK. In the
cytopathic effect, the results varied according to the isolate used, the dose used of
trophozoites and the passage in cell line. The increase in the number of amoeba
trophozoites in incubation with the cell lines was able to provoke an increase in the
virulence of the isolates of the three genotypes in the cytopathic effect test, especially
the VERO and CHO lines. In the cytopathic effect test, the most virulent genotype
was T5, followed by T4 and T3, the most virulent isolate was A3P4 (T5) of
environmental origin. Thus, it is concluded that the results obtained with the
cytopathic and cytotoxic effect tests with the different mammalian cell lines have
variations related to the type of mammalian cell line used, as well as the inherent
characteristics of each isolate. Therefore, the results obtained here may be useful for
the planning of future research related to the pathogenicity studies of Acanthamoeba.
