Correction: Serologically Defined Variations in Malaria Endemicity in Pará State, Brazil.

[This corrects the article DOI: 10.1371/journal.pone.0113357.]

Serologically defined variations in malaria endemicity in Pará state, Brazil

BACKGROUND: Measurement of malaria endemicity is typically based on vector or parasite measures. A complementary approach is the detection of parasite specific IgG antibodies. We determined the antibody levels and seroconversion rates to both P. vivax and P. falciparum merozoite antigens in individuals living in areas of varying P. vivax endemicity in Pará state, Brazilian Amazon region. METHODOLOGY/PRINCIPAL FINDINGS: The prevalence of antibodies to recombinant antigens from P. vivax and P. falciparum was determined in 1,330 individuals. Cross sectional surveys were conducted in the north of Brazil in Anajás, Belém, Goianésia do Pará, Jacareacanga, Itaituba, Trairão, all in the Pará state, and Sucuriju, a free-malaria site in the neighboring state Amapá. Seroprevalence to any P. vivax antigens (MSP1 or AMA-1) was 52.5%, whereas 24.7% of the individuals were seropositive to any P. falciparum antigens (MSP1 or AMA-1). For P. vivax antigens, the seroconversion rates (SCR) ranged from 0.005 (Sucuriju) to 0.201 (Goianésia do Pará), and are strongly correlated to the corresponding Annual Parasite Index (API). We detected two sites with distinct characteristics: Goianésia do Pará where seroprevalence curve does not change with age, and Sucuriju where seroprevalence curve is better described by a model with two SCRs compatible with a decrease in force of infection occurred 14 years ago (from 0.069 to 0.005). For P. falciparum antigens, current SCR estimates varied from 0.002 (Belém) to 0.018 (Goianésia do Pará). We also detected a putative decrease in disease transmission occurred ∼29 years ago in Anajás, Goianésia do Pará, Itaituba, Jacareacanga, and Trairão. CONCLUSIONS: We observed heterogeneity of serological indices across study sites with different endemicity levels and temporal changes in the force of infection in some of the sites. Our study provides further evidence that serology can be used to measure and monitor transmission of both major species of malaria parasite

Serologically Defined Variations in Malaria Endemicity in Pará State, Brazil. Supplementary dataset

An epidemiological and serological data set published to support the PLOS ONE paper, "Serologically Defined Variations in Malaria Endemicity in Pará State, Brazil". Data held on Figshare

Statistical analysis of antibody titers data.

<p>Age-adjusted log10-transformed antibody titer profiles for any <i>P. vivax</i> (blue solid lines) or <i>P. falciparum</i> antigens (red solid lines) using appropriate Michaelis-Menten models. Blue- and red-filled circles represent the observed mean antibody titer after pooling the data according to the 10%-centiles of the underlying age distribution. The antibody levels refer to the maximum among these reacting to AMA1 and the MSP1 antigens.</p

Baseline characteristics of the study area where all municipalities are in the Pará state with the exception of Sucuriju village (in the Amapá state).

a<p>Annual Parasite Index at the year of survey with the respective classification (low or high) as reported by the Brazilian Ministry of Health (<a href="http://www.saude.gov.br/sivep_malaria" target="_blank">www.saude.gov.br/sivep_malaria</a>).</p><p>Sucuriju village is usually considered as malaria-free area.</p><p>Baseline characteristics of the study area where all municipalities are in the Pará state with the exception of Sucuriju village (in the Amapá state).</p

Statistical analysis of seropositivity data.

<p><b>A</b>. Age-adjusted seroprevalence for any <i>P. vivax</i> (blue solid lines) or <i>P. falciparum</i> antigens (red solid lines) using appropriate reversible catalytic models. The observed seroprevalences for each <i>Plasmodium</i> species (blue- and red-filled circles) were pooled according to the 10%-centiles of the underlying age distribution. Note that Sucuriju data for <i>P. falciparum</i> were excluded from the analysis due to the small number of sero-positive individuals (two cases only). <b>B.</b> Correlation analysis for any <i>P. vivax</i> antigens using the annual parasite index versus seroconversion rate.</p

Statistical analysis of age-adjusted seroprevalence data using reversible catalytic models.

<p>For <i>P. vivax</i> seropositivity data the best model assumes (i) a single seroconversion rate for every site apart from Sucuriju where a changed in seroconversion rate seemed to have occurred 14 years ago and (ii) two seroreversion rates, one for Anajás, Jacareacanga, Goianésia do Pará, Itaituba and Trairão (ρ = 0.054, 95%CI = (0.033,0.081)), and another one for Sucuriju and Belém (ρ = 0.018, 95%CI = (0.002,0.039)). For <i>P. falciparum</i> data, the best model assumes: (i) a change in force of infection occurred 29 years ago and (ii) a common seroreversion rate for all study sites (ρ = 0.007, 95%CI = (0.001,0.029)). Data of Sucuriju was not analysed due to a low number of seropositive individuals for any <i>P. falciparum</i> antigens.</p><p>Statistical analysis of age-adjusted seroprevalence data using reversible catalytic models.</p

Parasite prevalence using thick blood smear and seroprevalence to any <i>P. vivax</i> and <i>P. falciparum</i> antigens and to any species.

a<p>Municipalities sorted by API at the year of the survey as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0113357#pone-0113357-t001" target="_blank">Table 1</a>.</p><p>Parasite prevalence using thick blood smear and seroprevalence to any <i>P. vivax</i> and <i>P. falciparum</i> antigens and to any species.</p

Map of the study area: A. South America, B. Brazil with Pará state in the Amazon region, C. The sampled six municipalities.

<p>Map of the study area: A. South America, B. Brazil with Pará state in the Amazon region, C. The sampled six municipalities.</p

Antioxidant and Neuroprotective Effects of the First Tryptophyllin Found in Snake Venom (Bothrops moojeni)

In this study, we report the isolation, characterization, and synthesis of the peptide BmT-2 belonging to the tryptophyllins family, isolated from the venom of the snake Bothrops moojeni. This is the first time a tryptophyllin is identified in snake venom. We tested whether BmT-2 had cytotoxic effects and antioxidant activity in a set of experiments that included both in vitro and cell-based assays. BmT-2 presented a radical scavenging activity toward ABTS• and AAPH-derived radicals. BmT-2 protected fluorescein, DNA molecules, and human red blood cells (RBCs) from free radicals generated by the thermal decomposition of AAPH. The novel tryptophyllin was not toxic in cell viability tests, where it (up to 0.4 mg/mL) did not cause hemolysis of human RBCs and did not cause significant loss of cell viability, showing a CC50 > 1.5 mM for cytotoxic effects against SK-N-BE(2) neuroblastoma cells. BmT-2 prevented the arsenite-induced upregulation of Nrf2 in Neuro-2a neuroblasts and the phorbol myristate acetate-induced overgeneration of reactive oxygen species and reactive nitrogen species in SK-N-BE(2) neuroblastoma cells. Electronic structure calculations and full atomistic reactive molecular dynamics simulations revealed the relevant contribution of aromatic residues in BmT-2 to its antioxidant properties. Our study presents a novel peptide classified into the family of the tryptophyllins, which has been reported exclusively in amphibians. Despite the promising results on its antioxidant activity and low cytotoxicity, the mechanisms of action of BmT-2 still need to be further elucidated