Understanding the complex mechanisms by which infectious agents can disrupt behavior represents a major challenge. The Borna disease virus (BDV), a potential human pathogen, provides a unique model to study such mechanisms. Because BDV induces neurodegeneration in brain areas that are still undergoing maturation at the time of infection, we tested the hypothesis that BDV interferes with neurogenesis. We showed that human neural stem/progenitor cells are highly permissive to BDV, although infection does not alter their survival or undifferentiated phenotype. In contrast, upon the induction of differentiation, BDV is capable of severely impairing neurogenesis by interfering with the survival of newly generated neurons. Such impairment was specific to neurogenesis, since astrogliogenesis was unaltered. In conclusion, we demonstrate a new mechanism by which BDV might impair neural function and brain plasticity in infected individuals. These results may contribute to a better understanding of behavioral disorders associated with BDV infection.

Fruits and vegetables may act as a vehicle of human enteric virus if they are irrigated with sewage-contaminated water or prepared by infected food handlers. An elution-concentration method was modified to efficiently detect, by reverse transcriptase-polymerase chain reaction (RT-PCR) or by cell culture, contamination by poliovirus, hepatitis A virus (HAV), and Norwalk-like virus (NLV) of various fresh and frozen berries and fresh vegetables. The protocol included washing the fruit or vegetable surface with 100 mM Tris-HCl, 50 mM glycine, and 3% beef extract, pH 9.5 buffer, which favors viral elution from acid-releasing berries, supplemented with 50 mM MgCl2 to reduce the decrease in viral infectivity during the process. The viral concentration method was based on polyethylene glycol precipitation. Copurified RT-PCR inhibitors and cytotoxic compounds were removed from viral concentrates by chloroform-butanol extraction. Viruses from 100 g of vegetal products could be recovered in volumes of 3 to 5 ml. Viral RNAs were isolated by a spin column method before molecular detection or concentrates were filtered (0.22-microm porosity) and inoculated on cell culture for infectious virus detection. About 15% of infectious poliovirus and 20% of infectious HAV were recovered from frozen raspberry surfaces. The percentage of viral RNA recovery was estimated by RT-PCR to be about 13% for NLV, 17% for HAV, and 45 to 100% for poliovirus. By this method, poliovirus and HAV RNA were detected on products inoculated with a titer of about 5 x 10(1) 50% tissue culture infectious dose per 100 g. NLV RNA was detected at an initial inoculum of 1.2 x 10(3) RT-PCR amplifiable units. This method would be useful for the viral analysis of fruits or vegetables during an epidemiological investigation of foodborne diseases.

In October 2000, bluetongue virus was detected on the French island of Corsica. The disease was also reported in Sardinia, Calabria, Sicily and on the Spanish islands of Majorca and Minorca. This paper describes the use of molecular techniques for a rapid identification and serotype determination of serotype 2 of the virus. The nucleotide sequences of segments 2 and 7 of the genome of the Corsican strain were determined and its phylogenetic relationships are described.

RÉSUMÉLes auteurs ont fait l'étude de la survie de Francise/la tularensis dans les organes, de souris mortes de tularémie, conservés plusieurs jours à différentes températures. Le germe ne survit pas plus de quatre à cinq jours à température ambiante ou à + 4 °C. Il survit au-delà de six jours dans les prélèvements congelés à -20 °C et à -80 °C à condition que ceux-ci soient faits tout de suite après la mort de l'animal.Mots-clés : Francise/la tu/arensis -Souris -Survie -Tularémie. SUMMARYThe authors have made the study of Francise/la tularensis survey and detection in organs of mice several days after their death, when the samples are keep at several temperature ( + 4°C, 20°C, -20°C, -80°C). The germe is not isolated after four or five days after the death at + 4°C or 20°C.