Predicting Transition Cow Health and Performance-Use of Blood and Fecal Biomarkers for Herd-Level Evaluation and Diagnostics

This information was presented at the 2012 NEDPA Conference, organized by the PRO-DAIRY program in the College of Agriculture and Life Sciences at Cornell University. The Northeast Dairy Producers Association (NEDPA) Conference is designed for producers and agriservice professionals to interact and relate to the latest thinking and issues in the dairy industry. Softcover copies of the entire conference proceedings may be purchased at http://www.ansci.cornell.edu/dm/proceedings_orders.html or by calling (607) 255-4285

Sistemas de efluxo multidrogas em Escherichia coli e uso de inibidores como possíveis adjuvantes na terapia da mastite bovina

Vinte e sete isolados de Escherichia coli provenientes de leite de bovinos com mastite clínica foram submetidos a teste de sensibilidade aos principais antimicrobianos usados no tratamento desta doença. Avaliou-se também a efetividade in vitro de dois inibidores de sistemas de efluxo multidrogas, fenilalanina arginyl ß naftilamida (PAβN) e 1-(1-Naphthylmethyl)-piperazine (NMP), utilizando-se a concentração inibitória mínima (CIM) como referência. A CIM e o sistema de efluxo foram detectados com base nas curvas de crescimento, utilizando-se a densidade óptica (D.O550), em diferentes concentrações da droga e na presença e ausência dos inibidores. Apenas quatro isolados apresentaram resistência à ampicilina e ao sulfametoxazol∕trimetoprim, simultaneamente, enquanto todos os 27 foram sensíveis aos demais antimicrobianos. Observaram-se valores para ampicilina variando de 6µg/mL a 250µg/mL e para sulfametoxazol∕trimetoprim de 12µg/mL a 1500µg/mL. Houve redução das CIMs desses antimicrobianos em todos os isolados na presença dos inibidores, exceto para sulfametoxazol∕trimetoprim na presença de NMP. Conclui-se que esses isolados possuem um estreito perfil de resistência e que PAßN apresentou melhor efeito inibitório em relação à ampicilina e ao sulfametoxazol∕trimetoprim, apresentando-se como um candidato a adjuvante no tratamento da mastite.Twenty-seven isolates of Escherichia coli from cattle with clinical mastitis were subjected to sensitivity tests regarding main antimicrobials used in the treatment of this disease. We also evaluated in vitro effectiveness of two inhibitors of multidrug efflux systems, fenilalanina arginyl ß naftilamida (PAβN) and 1-(1-Naphthylmethyl)-piperazine (NMP), using the minimum inhibitory concentration (MIC) as a reference. MIC and multidrug efflux systems were detected in the growth curves, using optical density (D.O550) at different drug concentrations and the presence and absence of inhibitors. Only four isolates of E. coli were resistant to ampicillin and trimethoprim/sulfamethoxazole, simultaneously. However, all isolates were sensitive to the other antimicrobials. Were observed values ranging from 6mg to 250mg ampicillin/mL, and 12mg to 1500mg/mL trimethoprim/sulfamethoxazole. There was a reduction of the MIC of antimicrobials for all isolates in the presence of inhibitors, except for trimethoprim/sulfamethoxazole in the presence of NMP. In conclusion, these isolates have a narrow resistance profile and PAßN showed better inhibitory effect against ampicillin and trimethoprim/sulfamethoxazole, and is a candidate for the adjuvant treatment of mastitis

On the evolution and function of Plasmodium vivax reticulocyte binding surface antigen (pvrbsa)

The RBSA protein is encoded by a gene described in Plasmodium species having tropism for reticulocytes. Since this protein is antigenic in natural infections and can bind to target cells, it has been proposed as a potential candidate for an anti-Plasmodium vivax vaccine. However, genetic diversity (a challenge which must be overcome for ensuring fully effective vaccine design) has not been described at this locus. Likewise, the minimum regions mediating specific parasite-host interaction have not been determined. This is why the rbsa gene's evolutionary history is being here described, as well as the P. vivax rbsa (pvrbsa) genetic diversity and the specific regions mediating parasite adhesion to reticulocytes. Unlike what has previously been reported, rbsa was also present in several parasite species belonging to the monkey-malaria clade; paralogs were also found in Plasmodium parasites invading reticulocytes. The pvrbsa locus had less diversity than other merozoite surface proteins where natural selection and recombination were the main evolutionary forces involved in causing the observed polymorphism. The N-terminal end (PvRBSA-A) was conserved and under functional constraint; consequently, it was expressed as recombinant protein for binding assays. This protein fragment bound to reticulocytes whilst the C-terminus, included in recombinant PvRBSA-B (which was not under functional constraint), did not. Interestingly, two PvRBSA-A-derived peptides were able to inhibit protein binding to reticulocytes. Specific conserved and functionally important peptides within PvRBSA-A could thus be considered when designing a fully-effective vaccine against P. vivax