Efficient assembly of full-length infectious clone of Brazilian IBDV isolate by homologous recombination in yeast

The Infectious Bursal Disease Virus (IBDV) causes immunosuppression in young chickens. Advances in molecular virology and vaccines for IBDV have been achieved by viral reverse genetics (VRG). VRG for IBDV has undergone changes over time, however all strategies used to generate particles of IBDV involves multiple rounds of amplification and need of in vitro ligation and restriction sites. The aim of this research was to build the world's first VRG for IBDV by yeast-based homologous recombination; a more efficient, robust and simple process than cloning by in vitro ligation. The wild type IBDV (Wt-IBDV-Br) was isolated in Brazil and had its genome cloned in pJG-CMV-HDR vector by yeast-based homologous recombination. The clones were transfected into chicken embryo fibroblasts and the recovered virus (IC-IBDV-Br) showed genetic stability and similar phenotype to Wt-IBDV-Br, which were observed by nucleotide sequence, focus size/morphology and replication kinetics, respectively. Thus, IBDV reverse genetics by yeast-based homologous recombination provides tools to IBDV understanding and vaccines/viral vectors development.

A spreadsheet for calculation of ingredients for standardization of requeijão cremoso / Planilha eletrônica para cálculos de ingredientes visando à padronização de requeijão cremoso

The standardization of requeijão cheese quality characteristics is a processing stage which is directly influenced by the chemical composition of the raw material. Fat and water concentrations are the main factors that cause variation in quality properties of the requeijão and, when not thoroughly controlled, may cause a lack in standardization of the food. Calculations of ingredients for effective standardization must be made in relation to the final product through of iterative calculations, which makes the manual process unfeasible. Thus, the objective of the present study was to develop a spreadsheet for ingredient calculation, with restrictions being the different concentrations of fat and water in order to standardize the final products. The spreadsheet was developed using the Excel 2007® Solver function, with just four input data: quantity of mass, water and fat content of the mass and fat content of the cream. The optimal solution was that which maximizes the amount of final product while meeting the stipulated constraints of fat and water. Results obtained with the spreadsheet were validated by processing the requeijão cheeses and comparison of the theoretical and practical parameters using the t-test. There was no significant difference between fat and water contents (p>0.10) estimated and verified in practice. Therefore, the use of the spreadsheet proved to be efficient for standardization of requeijão formulations.(AU)

A padronização das características de qualidade do requeijão é uma etapa do processamento, a qual é diretamente influenciada pela composição química da matéria-prima. Os teores de gordura e água são os principais fatores que acarretam variação nas propriedades de qualidade do requeijão e, quando não controlados minuciosamente, causam despadronização do alimento. Os cálculos de ingredientes para efetiva padronização devem ser realizados em relação ao produto final, por meio de cálculos iterativos, o que inviabiliza o processo manual. Nesse contexto, o presente trabalho teve por objetivo desenvolver uma planilha eletrônica para cálculo de ingredientes, tendo como restrições diferentes teores de gordura e água, visando à padronização dos produtos. A planilha foi desenvolvida utilizando-se o suplemento Solver do Excel2007®, sendo que os únicos parâmetros de entrada após a implementação da planilha foram: quantidade de massa, teor de gordura e de água na massa e teor de gordura do creme. A solução ótima foi a maximização da quantidade do produto final que satisfizesse as restrições dos teores de gordura e água estipulados. Os resultados obtidos pela planilha foram validados por meio do processamento dos requeijões e da comparação dos parâmetros teóricos e práticos utilizando-se o teste t. Não houve diferença significativa entre os teores de gordura e de água (p>0,10) estimados e verificados na prática. Portanto, a utilização da planilha eletrônica se apresenta eficiente para padronização de formulações de requeijão cremoso.(AU)