Banca de QUALIFICAÇÃO: MARIA FERNANDA BEZERRA DE SOUZA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARIA FERNANDA BEZERRA DE SOUZA
DATE: 17/11/2025
TIME: 09:30
LOCAL: Sala Carl Peter von Dietrich
TITLE:

Molecular approach based on the MSP1 gene for differential diagnosis of Plasmodium species in non-endemic regions of Brazil

KEY WORDS:

Plasmodium; Malaria; MSP1 gene; Molecular diagnosis; Nested-PCR; Non-endemic regions; Brazil.

PAGES: 104
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Malaria is a tropical infectious disease caused by protozoa of the genus Plasmodium and transmitted through the bite of infected female Anopheles mosquitoes. In Brazil, the Unified Health System (SUS) records malaria cases as infections by Plasmodium falciparum and/or non-falciparumPlasmodium, without distinguishing specific species, which compromises control and elimination strategies. In the Amazon region, most cases are caused by P. vivax, whereas P. falciparum predominates in extra-Amazonian areas, being associated with higher lethality. Infections by P. malariae and emerging zoonotic species such as P. simium and P. brasilianum have also been reported; these parasites exhibit high morphological, immunological, and molecular similarity to P. vivax, making microscopic diagnosis challenging. Although microscopy remains the gold standard for malaria diagnosis, its accuracy relies heavily on the examiner’s expertise. In non-endemic regions, the scarcity of skilled microscopists and the absence of routine diagnostic practices result in underreporting, diagnostic errors, and delayed treatment. Consequently, the malaria case-fatality rate in extra-Amazonian regions was 51 times higher than that observed in the Amazon in 2023, reaching 1.87%, although the northern region still accounts for approximately 99% of national cases. In this context, the present study aimed to develop and validate a molecular method based on nested-PCR targeting the MSP1 (merozoite surface protein 1) gene as a marker for differential diagnosis of P. vivax and P. falciparum. Twenty-five clinical samples from patients treated at the Dr. Heitor Vieira Dourado Tropical Medicine Foundation (FMT-HVD) in Manaus, previously diagnosed by Giemsa-stained thick blood smear microscopy, were analyzed. The study was approved by the FMT-HVD Research Ethics Committee (CAAE: 51071221.3.3001.5248; opinion: 5.180.415/2021). Genomic DNA was extracted from whole blood, and nested-PCR and electrophoresis assays were performed according to standardized laboratory protocols. The primer set designed from the MSP1 gene was evaluated both in silico and experimentally, resulting in a robust, sensitive, and reproducible assay suitable for application in both endemic and non-endemic areas. Results showed a high concordance between microscopy and nested-PCR, with no cross-reactivity observed between P. vivax and P. falciparum. The assay demonstrated the ability to detect low parasite densities, representing a significant advancement for the diagnosis of imported malaria cases in extra-Amazonian regions. Moreover, the scarcity of species-specific molecular tools and the limited availability of Brazilian Plasmodium sequences in genomic databases highlight the need to extend this approach to non-falciparum species such as P. malariae, P. ovale, P. brasilianum, and P. simium. Overall, this study demonstrates the potential of the MSP1-based nested-PCR as a complementary tool to conventional microscopy for malaria diagnosis, contributing to improved epidemiological surveillance and strengthening national strategies for malaria control and elimination in Brazil.

COMMITTEE MEMBERS:
Externa ao Programa - 2562988 - ANDREIA FERREIRA NERY - nullPresidente - 1046922 - LEONARDO CAPISTRANO FERREIRA
Interno - 2275890 - MARCELO DE SOUSA DA SILVA