Forty-two mussel and cockle samples were collected from two polluted areas of the Atlantic coast in France. No cytopathogenic enterovirus was isolated after inoculation to cell cultures, but enterovirus RNA was detected from 100% of the mussels and 80% of the cockle samples. Gene probes did not detect any HAV RNA but it was detected by PCR in 33% of cockle and 43% of mussel extracts. Infectious HAV could be isolated by inoculation to PLC/PRF/5 cells from five of six HAV-PCR positive samples. Viral indicators represented by somatic coliphages were present in 100% of the cockle and 86% of the mussel samples. Regarding bacterial indicators, 100% of the mussel and 95% of the cockle samples contained less than 300 faecal coliforms 100 g−1. No correlation could be established between the concentrations of faecal coliforms and streptococci, nor between the presence of somatic coliphages and the presence of virus or viral RNA.

Virucidal effect of UV light on hepatitis A virus was investigated in artificial sea water. Infectious virus was no longer detectable after 15 min irradiation of 3 liter experimentally contaminated water. Genomic amplification by polymerase chain reaction after reverse transcription allowed the detection of viral RNA in all samples even after 60 min irradiation.

Twenty-two mussel and cockle samples were collected after a hepatitis A outbreak on the Atlantic coast, in France. Detection of hepatitis A virus (HAV) antigen by radioimmunoassay and HAV RNA by hybridization were negative. However, HAV RNA was detected by reverse transcription and semi-nested polymerase chain reaction in 16 samples, and replication in cell culture was observed with four of them.

A commonly used technique to isolate rotaviruses from a water environment involves the inoculation on cell culture associated with the revelation of the viral multiplication by indirect immunofluorescence. The results of the experiment using this methodology may be expressed either with an enumerative technique or with a MPN technique. We have found that the enumerative method provided the highest yield as opposed to the MPN method by a ratio close to 3.7. According to the experimental conditions that were used, the enumerative method should be favored for the detection of viruses from a medium with low viral density br when quantifying viruses from a given sample. This work involves a comparative study where the MPN method is very attractive because of the ease of implementation and the rapidity with which results may be obtained.

Two concentration methods for recovering poliovirus from tap water are compared. Samples of tap water are artificially contaminated with poliovirus 1 Lsc 2ab and concentrated by adsorption-elution over either glass powder or glass wool. The results show that, for great viral contamination, the glass powder method provided a higher recovery yield than the glass wool method. But the glass wool method had the greater sensitivity. Viruses weredetectedin73.9% for viral contaminations of 4 to 50 PFU 20 l−1 when using the glass wool method although with the glass powder method viruses were detected in only 52.2 %.

The purpose of this paper is to evaluate the pollution introduced into the Morlaix estuary by the city discharge of sewage and to determine its consequences on the microbiological quality of estuarine water and sediment. It has been shown that between 10(13) and 10(14) fecal coliforms and streptococci and between 10(6) and 10(7) enteroviruses are thus conveyed per day. The study of the downstream contamination indicates that the bacterial and viral density is much more significant in the sediment and that the bacterial concentration decreases gradually from upstream to downstream whereas the viral density only varies slightly in the water and shows very irregular fluctuation in the sediment.

Two extraction-concentration methods for recovering rotavirus from mussels and oysters are compared. Molluscs are artificially contaminated by a one hour stay in seawater seeded with rotavirus SA 11. Results show that the first procedure using a glycine-NaCl pH 10 solution and an organic flocculation gives quite similar virus recovery from mussels and oysters, whatever the quantities of rotavirus in seawater are. The second procedure using a borate buffer - 3 % beef extract pH 9 and a double precipitation with Polyethylene glycol 6000 leads in most cases to a more efficient virus recovery, based on immunofluorescent foci counts on cover slip cultures of MA 104.

Virological analysis of seafood is often limited because of the toxic effects of the mollusc concentrates on cell cultures. We have developed a method of detoxification based on filtration through a Sephadex LH20 gel. Results show that in mussels concentrates after filtration the toxicity has decreased in a factor between 4 and 10 in 79 % of cases. With oysters the toxicity has decreased in a factor between 4 and 10 in 55 % of concentrates. Virus were recovered from 10 % mussels concentrates after filtration while no virus were recovered from crude concentrates before filtration. LH20 Sephadex filtration appears to be a simple method for decreasing shellfish tissues toxicity for cell cultures.

Three different extraction-concentration methods for virological analysis of sludge, marine and river sediments are studied. Enterovirus present in the concentrates were enumerated using the plaque technique with BGM cells. The results show that the indirect extraction technique isolated virus from the largest number of marine sediment samples. The direct extraction method is the best to recover virus from river sediments. Among the sludge samples, the number of positive samples did not vary much with the different techniques. It appears that there is no one universal method for virus concentration applicable to all categories of sediments and sludge.

Une etude effectuee sur le site de Barcelone a permis de mettre en evidence :1. La tres grande quantite de contaminations microbiologiques (bacteries, virus, oeufs d'helminthes) apportees par les eaux de rivieres, les eaux usees et les boues rejetees en mer.2. La faible concentration en enterovirus dans les sediments marins.3. L'importance des oeufs d'helminthes dans la contamination des sediments et le comportement different des oeufs de cestodes et de nematodes en milieu marin.4. L'impact apparement faible du rejet des boues en mer sur la contamination des sediments.