Cross-reactivity and inhibition myotoxic effects induced by Bothrops snake venoms using specific polyclonal anti-BnSP7 antibodies.

Polyclonal antibodies raised in Balb-c mice against BnSP-7, a Lys-49 phospholipase A2, were used to measure cross reactivity against other snake venoms. Using ELISA, these antibodies were able to recognize PLA2s isoforms present in venoms of botropic snakes at 1:6400, 1:3200 and 1:100 ratios (w/w). These antibodies highly recognized proteins of low molecular weight (∼14,000) from crude snake venom Bp and Bm by Western Blotting. PLA2 these venoms, by alignment of primary structures demonstrated high identity with BnSP-7 PLA2, especially in the C-terminal region. However, the crude snake venom Bd and Bj, showed low recognition. The PLA2 activity of Bothrops pauloensis, Bothrops moojeni venoms or BpPLA2-TXI was inhibited significantly when anti-BnSP-7 antibodies were incubated at 1:10 and 1:20 ratios (venoms or toxin:anti-BnSP-7, w/w), respectively. The myotoxic effect induced by the same venoms was also reduced significantly at 1:1, 1:10 and 1:20 ratios, by decreased creatine kinase levels. The anti-PLA2 polyclonal antibodies effectively recognized PLA2s from Bothrops pauloensis and Bothrops moojeni venoms, and neutralized specific catalytic and myotoxic activity.

DNA electrochemical biosensor for detection of Alicyclobacillus acidoterrestris utilizing Hoechst 33258 as indicator.

Alicyclobacillus acidoterrestris is an acidophilic and thermophilic bacterium present in the soil, often associated with the spoilage of acidic juices, such as orange juice. Their spores resist pasteurization and, when reactivated, modify the organoleptic properties of the juice, making it unsuitable for consumption, due mainly to production of guaiacol. Biosensors are detection devices that respond quickly and are easy to handle, with great potential for use in the juice production chain. In this context, this work reports an electrochemical genosensor for detection of A. acidoterrestris, based on a graphite electrode modified with electrochemically reduced graphene oxide, a polymer derived from 3-hydroxybenzoic acid and a specific DNA probe sequence complementary with the genomic DNA of A. acidoterrestris. Detection of the target was performed by monitoring the oxidation peak of the Hoechst 33258, a common DNA stainer. The genosensor detection limit was 12 ng mL-1 and it kept 77% of response after ten weeks, and a test showed that orange juice does not interfere with bacteria lysate detection. This biosensor is the first platform for electrochemical detection of the genomic DNA of A. acidoterrestris in the literature, and the first to use Hoechst 33258 as indicator with whole genomic DNA molecules.

A novel peptide-based sensor platform for detection of anti-Toxoplasma gondii immunoglobulins.

Toxoplasma gondii is an intracellular protozoan parasite responsible for toxoplasmosis, which affects humans and animals. Serologic detection of anti-T. gondii immunoglobulins plays a crucial role in the clinical diagnosis of toxoplasmosis. In this work, a novel electrochemical immunosensor for detecting anti-T. gondii immunoglobulins is reported, based on immobilization of an in silico predicted peptide (PepB3), obtained from membrane protein of T. gondii, on the graphite electrode modified with poly(3-hydroxybenzoic acid). Indirect ELISA confirmed infection and binding specificity of peptide PepB3. Molecular modelling and simulations show this peptide binds to the T. gondii human Fab antibody in the surface antigen 1 (SAG1) binding site, remaining a stable complex during the molecular dynamic simulations, especially by hydrogen bonds and hydrophobic interactions. This electrochemical immunosensor was able to discriminate different periods of infection, using infected mouse serum samples, showing selectivity and discriminating infected and uninfected mouse serum.

Development of direct assays for Toxoplasma gondii and its use in genomic DNA sample.

This work describes an approach for the selection and detection of specific DNA probes related to Toxoplasma gondii, a protozoan parasite responsible for toxoplasmosis. The detection system was developed on graphite carbon electrode modified with poly(3-hydroxybenzoic acid) sensitized with ToxG1 probe. The hybridization of the specific genomic DNA related to T. gondii showed good response by direct detection of guanine residue oxidation using differential pulse voltammetry (DPV). The biosensor was able to distinguish both the complementary and non-complementary targets and detect up to 100ngµL-1 of the T. gondii genomic DNA. The hybridization (ToxG1: T. gondii genomic DNA) was confirmed by optical measurement. Optical assays using gold nanoparticles:ToxG1 probe showed a significant change in the absorbance peak in the presence of the T. gondii genomic DNA according to the electrochemical results. This novel biosensor shows potential as electrochemical transducer and was successfully applied in the biological sample.

Bothrops pirajai snake venom L-amino acid oxidase: in vitro effects on infection of Toxoplasma gondii in human foreskin fibroblasts

The effect of an L-amino acid oxidase isolated from Bothrops pirajai snake venom (BpirLAAO-I) was investigated on infection of Toxoplasma gondii in human foreskin fibroblasts (HFF). The cytotoxic activity of BpirLAAO-I on HFF cells showed a dose-dependent toxicity with median cytotoxic dose (TD50) of 11.8 µg/mL. BpirLAAO-I induced considerable dose-dependent decrease in the T. gondii infection index under two different conditions, treatment of tachyzoites before infection or treatment of HFF cells after infection. A maximal inhibition of infection (56 percent) was found for treatment before infection, with a median inhibitory dose (ID50) at 1.83 µg/mL and selectivity index (SI) at 6.45. For treatment after infection, it was observed a maximal inhibition of infection at 65 percent, ID50 of 1.20 µg/mL and SI of 9.83. The treatment before infection was also effective to reduce intracellular parasitism up to 62 percent, although presenting higher values of ID50 (3.14 µg/mL) and lower values of SI (3.76). However, treatment after infection was not effective, suggesting that the enzyme seems to have no effect on the parasite intracellular replication for this condition. In conclusion, BpirLAAO-I was more effective to inhibit the infection of neighboring cells and consequently parasite dissemination than primary infection and parasite replication. Thus, the effect of BpirLAAO-I described herein could be taken into account for the development of new synthetic anti-parasite therapeutic agents.