A modelling approach to estimate the sensitivity of pooled faecal samples for isolation of Salmonella in pigs

The objective of this study was to develop and parametrize a mathematical model of the sensitivity of pooled sampling of faeces to detect Salmonella infection in pigs. A mathematical model was developed to represent the effect of pooling on the probability of Salmonella isolation. Parameters for the model were estimated using data obtained by collecting 50 faecal samples from each of two pig farms. Each sample was tested for Salmonella at individual sample weights of 0.1, 0.5, 1, 10 and 25 g and pools of 5, 10 and 20 samples were created from the individual samples. The highest test sensitivity for individual samples was found at 10 g (90% sensitivity), with the 25 g test sensitivity equal to 83%. For samples of less than 10 g, sensitivity was found to reduce with sample weight. Incubation for 48 h was found to produce a more sensitive test than incubation for 24 h. Model results found increasing sensitivity with more samples in the pool, with the pools of 5, 10 and 20 being more sensitive than individual sampling, and the pools of 20 being the most sensitive of those considered

Structural Basis of Pattern Recognition by Innate Immune Molecules

The importance of the innate immune system as a first line defence against pathogenic challenge has long been recognised. Over the last decade the identity of many of the key molecules mediating innate host defence have been clarified and a model of self/nonself discrimination by families of pattern recognition receptors (PRRs) has emerged. Although a large amount of information is now available concerning the action of these innate immune molecules at the level of the cell and organism, little is known about the molecular interface between pathogens and innate immune recognition molecules. In this chapter the molecular basis for innate immune discrimination of a wide variety of pathogen derived molecules is discussed in the context of the emerging literature