Sensitivity of field isolates of Eimeria acervulina and E. maxima from three regions in Brazil to eight anticoccidial drugs.

Rotation with different active ingredients is among the most effective and recommended strategies to preserve the efficacy of anticoccidial drugs and reduce the emergence of resistance. Tools such as anticoccidial sensitivity tests (ASTs) are ideally used to make rational rotation programs and bring benefits to production. The objective of this study was to evaluate the sensitivity of E. acervulina (EA) and E. maxima (EM) from 3 different regions in Brazil, by using four ASTs. Feces samples weighing 6 to 7 kg were collected in the regions of São Paulo, Paraná, and Minas Gerais. Prevalent oocysts from feces were filtered, identified, and quantified to conduct 2 ASTs with EA and 2 with EM. The same experimental design was used in every AST (4 replicates per treatment, with 6 birds each, for a total of 240 birds). Treatment groups were a nonchallenged and nonmedicated control group (T1), a challenged and nonmedicated control group (T2), and the other groups challenged and treated with the following compounds: lasalocid (90 ppm - T3), maduramycin (6 ppm - T4), decoquinate (30 ppm - T5), nicarbazin+semduramicin (66 ppm - T6), monensin (110 ppm - T7), salinomycin (66 ppm - T8), narasin+nicarbazin (100 ppm - T9), and nicarbazin (125 ppm - T10). At the end of each AST (20 d), the percent change (delta value) between the treated group (T3 to T10) and the control group (T2) was calculated for the following variables: body weight gain, feed conversion ratio, lesion score, and an indicator of percentage of optimal anticoccidial activity (POAA) that included T2. Different sensitivity levels of EA and EM isolates could be identified. As a whole, drugs from T5 and T3 groups showed higher delta values when compared to other compounds, whereas the lowest sensitivity levels of these isolates were observed in groups T4 and T7. Despite some limiting factors, ASTs can be a good tool for strategic selection of anticoccidial drugs in order to maintain efficacy and extend the lifespan of these molecules.

Predation on Diamondback Moth Larvae and Aphid by Resistant and Susceptible Lady Beetle, Eriopis connexa.

A successful pest control requires both chemical and biological agents for most commercially grown crops. However, insecticide resistance is increasing worldwide. Cabbage, a widely grown Brassicaceae, hosts the most resistant insect pest to insecticides, the diamondback moth (DBM), Plutella xylostella L. However, insecticide-resistant populations Eriopis connexa (Germar), a lady beetle often found controlling aphids and other soft-bodied pest species sharing brassica fields with DBM. Thus, as a model for integration of insecticide and biological control methods, we evaluated predation by pyrethroid-resistant and pyrethroid-susceptible lady beetles on DBM larvae offered alone and in the presence of a preferred prey, the aphid Lipaphis pseudobrassicae (Davis). During 24-h exposure, resistant and susceptible E. connexa consumed an average of 9.8 and 6.0 second-instar instar DBM larvae, respectively. Resistant beetles showed no significant preferences for prey consumption between untreated and deltamethrin-treated leaf surfaces, at field-recommended rate. As a function of DBM availability, resistant beetles exhibited similar predation on treated and untreated arena and higher predation than susceptible beetles in a treated arena. In greenhouse cages, resistant and susceptible beetles exhibited similar survival after 10 days on cabbage treated with deltamethrin and promoted the reduction of DBM to 5.0% and 5.6%, respectively. Both populations fed on a mixed diet of aphids and DBM larvae even under high availability of the preferred aphid prey. Resistant E. connexa survives deltamethrin exposure and do not alter their predatory behavior in response to this insecticide-treated environment.

Expression and purification of the immunogenically active fragment B of the Park Williams 8 Corynebacterium diphtheriae strain toxin.

The construction of a hexahistidine-tagged version of the B fragment of diphtheria toxin (DTB) represents an important step in the study of the biological properties of DTB because it will permit the production of pure recombinant DTB (rDTB) in less time and with higher yields than currently available. In the present study, the genomic DNA of the Corynebacterium diphtheriae Park Williams 8 (PW8) vaccine strain was used as a template for PCR amplification of the dtb gene. After amplification, the dtb gene was cloned and expressed in competent Escherichia coli M15 cells using the expression vector pQE-30. The lysate obtained from transformed E. coli cells containing the rDTB PW8 was clarified by centrifugation and purified by affinity chromatography. The homogeneity of the purified rDTB PW8 was confirmed by immunoblotting using mouse polyclonal anti-diphtheria toxoid antibodies and the immune response induced in animals with rDTB PW8 was evaluated by ELISA and dermonecrotic neutralization assays. The main result of the present study was an alternative and accessible method for the expression and purification of immunogenically reactive rDTB PW8 using commercially available systems. Data also provided preliminary evidence that rabbits immunized with rDTB PW8 are able to mount a neutralizing response against the challenge with toxigenic C. diphtheriae.

Expression and purification of the immunogenically active fragment B of the Park Williams 8 Corynebacterium diphtheriae strain toxin

The construction of a hexahistidine-tagged version of the B fragment of diphtheria toxin (DTB) represents an important step in the study of the biological properties of DTB because it will permit the production of pure recombinant DTB (rDTB) in less time and with higher yields than currently available. In the present study, the genomic DNA of the Corynebacterium diphtheriae Park Williams 8 (PW8) vaccine strain was used as a template for PCR amplification of the dtb gene. After amplification, the dtb gene was cloned and expressed in competent Escherichia coli M15™ cells using the expression vector pQE-30™. The lysate obtained from transformed E. coli cells containing the rDTB PW8 was clarified by centrifugation and purified by affinity chromatography. The homogeneity of the purified rDTB PW8 was confirmed by immunoblotting using mouse polyclonal anti-diphtheria toxoid antibodies and the immune response induced in animals with rDTB PW8 was evaluated by ELISA and dermonecrotic neutralization assays. The main result of the present study was an alternative and accessible method for the expression and purification of immunogenically reactive rDTB PW8 using commercially available systems. Data also provided preliminary evidence that rabbits immunized with rDTB PW8 are able to mount a neutralizing response against the challenge with toxigenic C. diphtheriae.

Improvement of the lymphoproliferative immune response and apoptosis inhibition upon in vitro treatment with zinc of peripheral blood mononuclear cells (PBMC) from HIV+ individuals.

Clinical improvement has been described in AIDS patients submitted to zinc therapy, but the mechanisms involved are not well understood. In order to evaluate the effect of the zinc ions in the enhancement of the immune response, we tested its role in the lymphoproliferative response to a mitogen, as well as in the prevention of apoptosis. The mitogenic effect of zinc (10(-4)M ZnCl2) on the lymphocyte proliferative response was observed in healthy controls as well as in HIV-1+ asymptomatic individuals. Very low stimulation index could be observed in AIDS patients (CD4+<200/mm3). However, zinc treatment of phytohaemagglutinin (PHA; 5 microg/ml)-stimulated PBMC cultures significantly enhanced 3H-thymidine incorporation in both asymptomatic and symptomatic groups. A decreased percentage of apoptotic cells could be identified in cell cultures from HIV-1+ individuals submitted to zinc treatment compared with cells treated only with PHA, as detected by both flow cytometry and agarose gel electrophoresis. Further studies with zinc supplementation associated to anti-retroviral therapy would be of great interest to evaluate the in vivo role of this oligoelement in the improvement of the immunological functions of HIV-1-infected individuals and AIDS patients.