A qualitative risk assessment methodology for scientific expert panels.

Risk assessment can be either quantitative, i.e. providing a numeric estimate of the probability of risk and the magnitude of the consequences, or qualitative, using a descriptive approach. The French Agency for Food, Environmental and Occupational Health and Safety (ANSES), formerly the French Food Safety Agency (AFSSA), bases its assessments on the opinions of scientific panels, such as the ANSES Animal Health Scientific Panel (AH-SP). Owing to the lack of relevant data and the very short period of time usually allowed to assess animal health risks on particular topics, this panel has been using a qualitative risk method for evaluating animal health risks or crises for the past few years. Some experts have drawn attention to the limitations of this method, such as the need to extend the range of adjectives used for the lower probabilities and to develop a way to assess consequences. The aim of this paper is to describe the improved method now established by the AH-SP, taking into account the limitations of the first version. The authors describe a new set of levels for probabilities, as well as the items considered when addressing either animal or human health consequences.

Cytoplasmic and outer membranes separation in Rhodopseudomonas sphaeroides.

A cell envelope fraction had been prepared after mechanical disruption of lysozyme-EDTA spheroplasts from depigmented Rhodopseudomonas sphaeroides (aerobically grown in the light). On linear sucrose gradients this fraction can be separated in a cytoplasmic membrane fraction and an outer membrane fraction. The cytoplasmic fraction (buoyant density: 1.18 g/cm3) has been characterized by its succinic dehydrogenase activity and by its composition. The outer membrane fraction (buoyant density: 1.21 g/cm3) does not contain any respiratory activity nor hemoproteins. The same fractionation has been done on cells repigmented in the dark by lowering the O2 pressure. In that case the same two fractions have been detected in addition to the chromatophore fraction (buoyant density: 1.14 g/cm3). However both, and specially the outer membrane fraction, were contaminated by chromatophore material.

Genetic immunization of seronegative one-day-old piglets against pseudorabies induces neutralizing antibodies but not protection and is ineffective in piglets from immune dams.

Immune response inhibition by maternal antibodies is a major impediment to the vaccination of the young born to immune dams. This study explored the efficiency of genetic immunization of the neonates at bypassing this inhibition, by testing the muscular inoculation of the gD glycoprotein gene of pseudorabies virus (PRV) in piglets. Plasmid DNA (400 micrograms) was inoculated in four groups of one-day-old piglets, from sows vaccinated or not against PRV. Half of the groups received a booster injection on day 42. All piglets were challenged on day 115. Only piglets from non-immune sows and which received a booster injection developed a medium level of neutralizing antibodies, but they were not significantly protected against the challenge. Piglets from immune sows neither developed an antibody response nor were primed against PRV, as demonstrated by the antibodies kinetics after challenge. It can therefore be concluded that genetic immunization was inefficient at efficiently preventing the immune response inhibition by colostral antibodies.