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The identification of antifungal compounds produced by microorganisms is crucial in the context of sustainable agriculture. Bacteria of the genus Bacillus have a broad spectrum of action that can influence plant growth and control pests, vectors of public health relevance and phytopathogens. Lipopeptides are the main compounds related to the biological control of several pathogen species. Strains with biotechnological potential are identified by means of in vitro bioassays and molecular tests. In this study, strains from the Bacillus Bank of Brazilian Agricultural Research Corporation (EMBRAPA/DF/Brazil) were selected to control the fungal pathogens Sclerotinia sclerotiorum and Fusarium oxysporum by pairing assays. The detection of genes for biosynthesis of antifungal compounds from strains with high pathogen-inhibition capacity was correlated with peptide synthesis, such as bacillomycin D, fengycin d, bacilysin and surfactin. Their gene expression in contact with the pathogen was analyzed by Real-Time PCR. The volatile organic compounds produced by selected Bacillus strains were identified and quantified. In co-culture assays, the inhibition zone between Bacillus strains and Sclerotinia sclerotiorum was evaluated by scanning electron microscopy. Thirteen potentially anti-pathogenic strains were selected. Genes related to the synthesis of antifungal peptides were detected in 11 of them. In five strains, all tested genes were detected. Bacillomycin was the most frequently found lipopeptide gene. The fungus-bacteria interaction potentiated the production of volatiles. Several ketones and other volatile compounds with antifungal activity were identified. Relevant morphological changes in the fungus were observed when paired with bacteria. The study demonstrated the efficacy of the selected strains with regard to the biological control of phytopathogens and their biotechnological potential. [ABSTRACT FROM AUTHOR]

Background: Leishmaniasis is one of the most important zoonotic diseases spread in Latin America. Since many species are involved in dog infection with different clinical manifestations, the development of specific diagnostic tests is mandatory for more accurate disease control and vaccine strategies. Methodology/Principal findings: Seventy-five 15-mer peptides covering the sequence of recombinant Leishmania donovani virulence factor A2 (recLdVFA2) protein were prepared by Spot synthesis. Membrane-bound peptides immunoreactivity with sera from dogs immunized with recLdVFA2 and with a specific anti-recLdVFA2 monoclonal antibody allowed mapping of continuous B-cell epitopes. Five epitopes corresponding to the N-terminal region of recLdVFA2 (MKIRSVRPLVVLLVC, RSVRPLVVLLVCVAA, RPLVVLLVCVAAVLA, VVLLVCVAAVLALSA and LVCVAAVLALSASAE, region 1–28) and one located within the repetitive units (PLSVGPQAVGLSVG, regions 67–81 and 122–135) were identified. A 34-mer recLdVFA2-derived bi-epitope containing the sequence MKIRSVRPLVVLLVC linked to PLSVGPQAVGLSVG by a Gly-Gly spacer was chemically synthesized in its soluble form. The synthetic bi-epitope was used as antigen to coat ELISA plates and assayed with dog sera for in vitro diagnosis of canine visceral leishmaniasis (CVL). The assay proved to be highly sensitive (100%) and specific (100%). Conclusions/Significance: Our work suggests that synthetic peptide-based ELISA strategy may be useful for the development of a sensitive and highly specific serodiagnosis for CVL or other parasitic diseases. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) from the dermaseptin and phylloseptin families were isolated from the skin secretion of Phyllomedusa nordestina, a recently described amphibian species from Northeastern Brazil. One dermaseptin and three phylloseptins were chosen for solid phase peptide synthesis. The antiprotozoal and antimicrobial activities of the synthetic peptides were determined, as well as their cytotoxicity in mouse peritoneal cells. AMPs are being considered as frameworks for the development of novel drugs inspired by their mechanism of action. [ABSTRACT FROM AUTHOR]

Abstract: Plasmodium vivax merozoite surface protein (PvMSP9) stimulates both cellular and humoral immune responses in individuals who are naturally infected by this parasite species. To identify immunodominant human T-cell epitopes in PvMSP9, we used the MHC class II binding peptide prediction algorithm ProPred. Eleven synthetic peptides representing predicted putative promiscuous T-cell epitopes were tested in IFN-γ and IL-4 ELISPOT assays using peripheral blood mononuclear cells (PBMC) derived from 142 individuals from Rondonia State, Brazil who had been naturally exposed to P. vivax infections. To determine whether the predicted epitopes are preferentially recognized in the context of multiple alleles, MHC Class II typing of the cohort was also performed. Five synthetic peptides elicited robust cellular responses, and the overall frequencies of IFN-γ and IL-4 responders to at least one of the promiscuous peptides were 62% and 46%, respectively. The frequencies of IFN-γ and IL-4 responders to each peptide were not associated with a particular HLA-DRB1 allelic group since most of the peptides induced a response in individuals of 12 out of 13 studied allelic groups. The prediction of promiscuous epitopes using ProPred led to the identification of immunodominant epitopes recognized by PBMC from a significant proportion of a genetically heterogeneous population exposed to malaria infections. The combination of several such T-cell epitopes in a vaccine construct may increase the frequency of responders and the overall efficacy of subunit vaccines in genetically distinct populations. [Copyright &y& Elsevier]