Sewage impact on shellfish microbial contamination.

Coastal areas are frequently contaminated by microorganisms of human origin, due to high population density and low seawater renewal. To evaluate the impact of wastewater input on shellfish quality, a study was conducted in Brittany (France) over a period of 20 months. A hydrodynamic model was used to simulate wastewater impact on microbial water quality. To validate the model, wastewater from the three main sewage treatment plants and shellfish from three sites were sampled monthly. Bacterial indicators (E. coli), F-RNA phages were searched for by culture and noroviruses by RT-PCR and hybridisation. These microorganisms were detected in the three effluents and clams, with no marked seasonal variation. The microbial concentrations in the two oyster beds, distant from the effluent outfall, were low, and only three of the samples were positive for norovirus. For simulation, the winter wastewater inputs of E. coli and phages were calculated and an estimation for norovirus flux was made from the epidemic situation in the population. The microbial behaviour was included in the model by a decay-rate factor. Results from the model calculations were found to be very similar to E. coli and phage concentrations observed in shellfish. For noroviruses, the model indicated that shellfish distant from the wastewater input were under the detection limit of the RT-PCR method. This study demonstrated the use of modelisation to interpret norovirus contamination in various areas.

[Use of cell culture for the research of cytotoxic and antiviral effects of a natural extract of Amaryllidaceae]. / Utilisation des cultures cellulaires pour la recherche des effets cytotoxiques et antiviraux d'un extrait naturel d'Amaryllidaceae.

The use of tissue culture for evaluation of antiviral agents can provide rapid information on the toxicity induced by drugs. Toxicity is assessed through 4 different tests: observation through a light microscope, colorimetric evaluation of living cells stained with MTT (Methyl Thiazol Tetrazolium), colorimetric evaluation of fixed cells stained with crystal violet, inhibition of incorporation of radioactive labelled precursors specific to the synthesis under study. These tests allowing evaluation of effects on cell morphological changes (1), of modifications of mitochondrial and enzymatic activities in the cytoplasm (2), of effects on cell growth (3) and on their major synthesis [ADN, ARN, proteins] (4). This design of experiments has been applied to an hydroalcoolic extract from Haemanthus albiflos (Amaryllidaceae) tested for its antiviral properties towards Poliovirus type 1 propagated on monkey kidney cells line (MA 104). The maximum tolerated dose by the cell and the inhibition of virus replication were determined according to tests 2 and 3. The sensitive step of the virus replication cycle was investigated using test 4. Concentration of 7 microliters/ml plant extract showed: 20% cytotoxicity (MTT test). At 7 microliters/ml plant extract the inhibition of replication virus is 4.5 log units (microplates assay) and inhibition of proteins viral synthesis is 97% compared with the control.

[Study of antiviral action of total alkaloids from Haemanthus albiflos]. / Etude de l'action antivirale des alcaloïdes totaux d'Haemanthus albiflos.

Investigations were undertaken on the antiviral action level of an alkaloïd extract from Haemanthus albiflos bulb, earlier reported as efficient against RNA viruses. Rotavirus propagated on MA 104 cells with different concentrations of the extract was used in the assays. Incidence on cellular and viral RNA synthesis was evaluated by measuring the radioactivity incorporated using labelled precursors. An inhibition of 42% and 79% of the cellular RNA synthesis was observed when respectively 25 microliters/ml and 50 microliters/ml concentrations of the alkaloïd extract were tested. After 20 h incubation a decrease of the viral RNA synthesis was observed. It was of 46%, 36% and 27% compared to the control when respectively 25 microliters/ml, 50 microliters/ml and 100 microliters/ml concentrations of the extract were tested. Besides, the maximum viral production was delayed parallelly to the increase of the extract concentration. A similar viral synthesis inhibition was obtained after only 4 hours incubation suggesting that the extract interfere in the early events of the viral cycle.

[Plants as a source of research in antiviral activity. Example of the Haemanthus albiflos bulb]. / Les plantes comme source de recherche d'activité antivirale. Exemple du bulbe d'haemanthus albiflos.

The antiviral potency of an hydroalcoholic extract from Haemanthus albiflos (AMARYLLIDACEAE) bulb was investigated. Experimentations were conducted on continuous cell lines (BGM, MA 104, Hep 2) seeded in microplates. Three viruses from the RNA group (Poliovirus type I, Vesicular Stomatitis Virus type 11 and Simian Rotavirus SA 11) and two from the DNA group (Adenovirus type 5, Herpes Simplex Virus type 1) were tested. Important reduction in yield of viral infectivity was observed with the RNA group (respectively 6,4 and 4,5 logarithmic units order of magnitude).

[Antiviral effect of Haemanthus albiflos leaves extract on herpes virus, adenovirus, vesicular stomatitis virus, rotavirus and poliovirus]. / Effet antiviral d'un extrait de feuilles d'Haemanthus albiflos sur le virus de l'herpès, l'Adénovirus, le virus de la stomatite vésiculeuse, le Rotavirus et le Poliovirus.

An hydro-alcoholic extract from Haemanthus albiflos leaves (Amaryllidaceae) was tested for its potential antiviral activity against two DNA viruses: herpes simplex virus type I, Adenovirus type 5 and three RNA viruses: poliovirus type I, vesicular stomatitis virus, simian Rotavirus SA 11. Positive results were obtained against herpes virus and all the RNA viruses tested.

[Continuous detection of poliovirus in public water supplies]. / Détection en continu du poliovirus dans des eaux de distribution publique.

Continuous virological control can be carried out when using glass wool as an adsorption support for virus concentration. In the described conditions more than 70% of the Poliovirus population in water pipe derivations can be detected.

[Inhibition of poliovirus replication by an extract of Matricaria chamomilla (L)]. / Inhibition de la replication du Poliovirus par un extrait de Matricaria chamomilla (L).

Hydroalcoholic extract of Matricaria chamomilla added during the early stage of Poliovirus development inhibits cellular and viral RNA synthesis. This inhibition is partially reversible.

Preformed magnesium hydroxide precipitate for second-step concentration of enteroviruses from drinking and surface waters.

A method is described for the second-step concentration of viruses from large volumes of drinking and surface waters. Seeded viruses present in the first eluate, performed with 50 mM glycine buffer, pH 11.5, were adsorbed on a preformed magnesium hydroxide precipitate. After low-speed centrifugation they were desorbed and adjusted to pH 7 with McIlvaine citrate-phosphate buffer. In these experimental conditions 90% of the viruses present in the 300-mL first eluate were reconcentrated in a final volume of 40 mL. The recovery efficiency was independent of either virus concentration or water quality.