Naturally Acquired Humoral Immunity against Malaria Parasites in Non-Human Primates from the Brazilian Amazon, Cerrado and Atlantic Forest.

Eliana Ferreira Monteiro,Stéfanie Vanessa Santos,Carolina Romeiro Fernandes Chagas,Marina Galvão Bueno,Julio Cesar De Souza,Luiz Shozo Ozaki,Karin Kirchgatter,Bruno Da Silva Mathias,Maisa Da Silva Araujo,Carmen Fernandez-Becerra,Mariluce Rezende Messias,Ana Maria Ribeiro De Castro Duarte,Jose Luiz Catao-Dias,Mayra Gomes Dos Santos,Marcia Moreira Holcman

doi:10.3390/pathogens9070525

Abstract

Non-human primates (NHPs) have been shown to be infected by parasites of the genus Plasmodium, the etiological agent of malaria in humans, creating potential risks of zoonotic transmission. Plasmodium brasilianum, a parasite species similar to P. malariae of humans, have been described in NHPs from Central and South America, including Brazil. The merozoite surface protein 1 (MSP1), besides being a malaria vaccine candidate, is highly immunogenic. Due to such properties, we tested this protein for the diagnosis of parasite infection. We used recombinant proteins of P. malariae MSP1, as well as of P. falciparum and P. vivax, for the detection of antibodies anti-MSP1 of these parasite species, in the sera of NHPs collected in different regions of Brazil. About 40% of the NHP sera were confirmed as reactive to the proteins of one or more parasite species. A relatively higher number of reactive sera was found in animals from the Atlantic Forest than those from the Amazon region, possibly reflecting the former more intense parasite circulation among NHPs due to their proximity to humans at a higher populational density. The presence of Plasmodium positive NHPs in the surveyed areas, being therefore potential parasite reservoirs, needs to be considered in any malaria surveillance program.

Highlights

The merozoite surface protein 1 (MSP1) is the most abundant protein on the malaria parasite cell surface
Quality control of the coupling was placed on each plate, where the beads that were covalently coated with the different recombinant proteins were tested in the same plate, with biotinylated anti-GST, to evaluate the efficiency of the coupling and verify the reading behavior of each protein
Brazil is home to far more non-human primates than any other country; its 110 species account for about 27%, or one in every four, Non-human primates (NHPs) in the world

Summary

Introduction

The merozoite surface protein 1 (MSP1) is the most abundant protein on the malaria parasite cell surface. It is involved in the erythrocyte invasion process, being one of the most studied targets for a malaria vaccine [1]. MSP1 is synthesized from the onset of schizogony [2] and transported to the surface of the parasite cell, together with the proteins MSP6 and MSP7 as a complex, where it is retained through its glycosyl phosphatidylinositol (GPI) anchor. The egress of merozoites from erythrocytes is accompanied by a primary proteolytic processing of MSP1 that results in a protein complex on the surface of the merozoite cells (reviewed in [1]). Analyses of the pmmsp gene was performed through the amplification and sequencing of five fragments, F1 to F5 (F5 named PmMSP119 ), equivalent to blocks 3 to 17 of the PfMSP1

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Conclusion