Construction, Expression, and Evaluation of the Naturally Acquired Humoral Immune Response against RMC-1, a Multistage Chimeric Protein.

The PvCelTOS, PvCyRPA, and Pvs25 proteins play important roles during the three stages of the lifecycle. In this study, we designed and expressed a recombinant modular chimeric protein (PvRMC-1) composed of the main antigenic regions of these vaccine candidates. After structure modelling by prediction, the chimeric protein was expressed, and the antigenicity was assessed by IgM and IgG (total and subclass) ELISA in 301 naturally exposed individuals from the Brazilian Amazon.

B-Cell Epitope Mapping of the Malaria Vaccine Candidate GMZ2.6c in a Naturally Exposed Population of the Brazilian Amazon.

The GMZ2.6c malaria vaccine candidate is a multi-stage chimeric protein that contains a fragment of the sexual-stage s48/45-6C protein genetically fused to GMZ2, an asexual-stage vaccine construction consisting of the N-terminal region of the glutamate-rich protein (GLURP) and the C-terminal region of the merozoite surface protein-3 (MSP-3). Previous studies showed that GMZ2.

Naturally acquired antibody response to a Plasmodium falciparum chimeric vaccine candidate GMZ2.6c and its components (MSP-3, GLURP, and Pfs48/45) in individuals living in Brazilian malaria-endemic areas.

Background: The GMZ2.6c malaria vaccine candidate is a multi-stage Plasmodium falciparum chimeric protein which contains a fragment of the sexual-stage Pfs48/45-6C protein genetically fused to GMZ2, a fusion protein of GLURP and MSP-3, that has been shown to be well tolerated, safe and immunogenic in clinical trials performed in a malaria-endemic area of Africa. However, there is no data available on the antigenicity or immunogenicity of GMZ2.

Plasmodium vivax metacaspase 1 (PvMCA1) catalytic domain is conserved in field isolates from Brazilian Amazon.

In the present study, we investigated the genetic diversity of Plasmodium vivax metacaspase 1 (PvMCA1) catalytic domain in two municipalities of the main malaria hotspot in Brazil, i.e., the Juruá Valley, and observed complete sequence identity among all P.

Chloroquine and mefloquine resistance profiles are not related to the circumsporozoite protein (CSP) VK210 subtypes in field isolates of Plasmodium vivax from Manaus, Brazilian Amazon.

Background: The central repetitive region (CRR) of the Plasmodium vivax circumsporozoite surface protein (CSP) is composed of a repetitive sequence that is characterised by three variants: VK210, VK247 and P. vivax-like. The most important challenge in the treatment of P.

Plasmodium vivax ookinete surface protein (Pvs25) is highly conserved among field isolates from five different regions of the Brazilian Amazon.

The Plasmodium vivax Ookinete Surface Protein (Pvs25) is one of the leading malaria Transmission-Blocking Vaccine candidates based on its high immunogenicity in animal models, transmission-blocking activity of antibodies elicited in clinical trials and high conservation among P. vivax isolates from endemic areas. However, the polymorphism in gene encoding Pvs25 in endemic areas from South America has been poorly studied so far.

Increased Parasitemia in Non-splenectomized Monkeys Treated with Clodronate Liposomes.

A major constraint in the study of malaria, including vaccine development, lies on the parasite's strict human host specificity and therefore the shortage of animal experimental models able to harbor human plasmodia. The best experimental models are neo-tropical primates of the genus Saimiri and Aotus, but they require splenectomy to reduce innate defenses for achieving high and consistent parasitemias, an important limitation. Clodronate-liposomes (CL) have been successfully used to deplete monocytes/macrophages in several experimental models.

Molecular and immunological tools for the evaluation of the cellular immune response in the neotropical monkey Saimiri sciureus, a non-human primate model for malaria research.

Background: The neotropical, non-human primates (NHP) of the genus Saimiri and Aotus are recommended by the World Health Organization as experimental models for the study of human malaria because these animals can be infected with the same Plasmodium that cause malaria in humans. However, one limitation is the lack of immunological tools to assess the immune response in these models. The present study focuses on the development and comparative use of molecular and immunological methods to evaluate the cellular immune response in Saimiri sciureus.

Cellular and humoral immune responses against the Plasmodium vivax MSP-1₁₉ malaria vaccine candidate in individuals living in an endemic area in north-eastern Amazon region of Brazil.

Background: Plasmodium vivax merozoite surface protein-1 (MSP-1) is an antigen considered to be one of the leading malaria vaccine candidates. PvMSP-1 is highly immunogenic and evidences suggest that it is target for protective immunity against asexual blood stages of malaria parasites. Thus, this study aims to evaluate the acquired cellular and antibody immune responses against PvMSP-1 in individuals naturally exposed to malaria infections in a malaria-endemic area in the north-eastern Amazon region of Brazil.

Antibodies against the Plasmodium falciparum glutamate-rich protein from naturally exposed individuals living in a Brazilian malaria-endemic area can inhibit in vitro parasite growth.

The glutamate-rich protein (GLURP) is an exoantigen expressed in all stages of the Plasmodium falciparum life cycle in humans. Anti-GLURP antibodies can inhibit parasite growth in the presence of monocytes via antibody-dependent cellular inhibition (ADCI), and a major parasite-inhibitory region has been found in the N-terminal R0 region of the protein. Herein, we describe the antiplasmodial activity of anti-GLURP antibodies present in the sera from individuals naturally exposed to malaria in a Brazilian malaria-endemic area.

Sera of patients with systemic lupus erythematosus react with plasmodial antigens and can inhibit the in vitro growth of Plasmodium falciparum.

The acquisition of protective immunity in malaria is a slow process during which autoantibodies are produced. The present work aimed at studying a possible interference of autoimmune responses on malaria immune protection. This was done by investigating the presence of autoantibodies in the sera of malarious patients, by searching for reactivity of autoantibodies from autoimmune patients against plasmodial antigens, and by studying the effect of such antibodies on the in vitro growth of Plasmodium falciparum.

Dexamethasone has pro-apoptotic effects on non-activated fresh peripheral blood mononuclear cells.

Apoptosis is a physiological method of cell death commonly referred to as programmed cell death. However, non-apoptotic programmed cell death, such as autophagy and programmed necrosis, has been characterized by morphological criteria. In view of the human therapeutic use of DEX, and considering that no difference in the number and/or affinity of glucocorticoid receptors in activated and non-activated lymphocytes has been reported, we decided to evaluate the effect of DEX on fresh peripheral blood mononuclear cells (PBMC).

Malaria associated apoptosis is not significantly correlated with either parasitemia or the number of previous malaria attacks.

The occurrence and intensity of lymphocyte apoptosis in blood samples from 79 outclinic patients with uncomplicated Plasmodium falciparum or Plasmodium vivax malaria and 30 healthy individuals were investigated. No difference in apoptosis percentages was detected between healthy individuals and malaria patients when ex vivo lymphocytes were analyzed. However, significantly increased apoptosis levels were observed in lymphocytes from both P.

Cryopreservation of peripheral blood mononuclear cells does not significantly affect the levels of spontaneous apoptosis after 24-h culture.

Studies performed with malaria patients living in endemic areas are frequently conducted in laboratories located hundreds of kilometer away from research centers, due to the difficulties in performing the assays in field conditions. Thus, we considered the potential indication of cryopreservation of peripheral blood mononuclear cells (PBMC), in most fieldwork, and decided to evaluate the effect of cryopreservation of PBMC on spontaneous apoptosis. The membrane integrity of PBMC was tested using three previously described protocols of cryopreservation.