Louis Schwartzbrod

Presence of Viral Genomes in Mineral Water: a Sufficient Condition To Assume Infectious Risk?

ABSTRACT Appropriate interpretation of a positive reverse transcription-PCR is an important issue for virus-related health hazard assessment because viral genomes and infectious viruses exhibit different behavior patterns in water. In this context, using Poliovirus 1 and Feline calicivirus f9 as examples of enteric viruses, first we demonstrated that the stability of infectious viruses is greatly affected by the temperature of mineral water (10, 20, and 35°C) and that, in contrast, temperature has little effect on the corresponding genomes. Second, we demonstrated that infectious particles are degraded more rapidly than viral genomes at all temperatures studied. At 35°C, Poliovirus 1 infectivity was reduced 4 logs after only 19 days, while an equivalent reduction would have taken 75 years (according to the model applied) for the viral genome. Contradictory conclusions can also be drawn concerning the sensitivity of viral serotypes depending on whether the infectious virus or the viral genome is considered. The Feline calicivirus f9 genome is more resistant than the Poliovirus 1 genome, whereas the opposite is true for the corresponding infectious viruses. Thus, we concluded that a positive test for a viral genome in mineral water must be interpreted with utmost caution because of the lack of a correlation between the presence of viral genomes and viral infectivity. Detection of viral genomes may be necessary to identify infectious risk for the human population, but it cannot be considered sufficient.

Bacteroides fragilis and Escherichia coli bacteriophages in human faeces

Some bacteriophages found in human faeces are being evaluated as possible indicators of viral contamination of water. These bacteriophages include somatic coliphages and Bacteroides fragilis phages. The aims of this study were to determine the occurrence and concentrations of somatic coliphages and Bacteroides fragilis phages in the stools of a human population residing in eastern France (n = 193). Somatic coliphages were detected in 68% of the stools at a mean concentration of 4.3 x 10(3) PFU.g-1 and Bacteroides fragilis phages were detected in 11% of the stools at a mean concentration of 7 x 10(1) PFU.g-1. Statistical analysis showed no correlation between the phage concentration and the age or sex of the human subject.

Poliovirus‐1 adsorption onto and desorption from montmorillonite in seawater. Survival of the adsorbed virus

Abstract It is an acknowledged fact that most viruses in the aquatic medium are present in an aggregated form or adsorbed to particulate matter and especially clay matter. This adsorption is a parameter that must be taken into account when dealing with the natural inactivation of viruses in an aquatic medium. The adsorption of poliovirus‐1 in seawater was examined on Na‐montmorillonite. It proved to be a quick (less than 30 min) and mass phenomenom depending on the Na‐montmorillonite concentration. As a matter of fact, whereas more than 99.9% of viruses are adsorbed in less than 30 min in the presence of 500 mg.l‐1 of Na‐montmorillonite, the adsorption percentage under the same conditions is yet around 70% with a concentration of 3 mg.l‐1. A comparison between the survival durations of poliovirus‐1, be it free or adsorbed onto Na‐montmorillonite in a seawater with a salinity of 33 g.l‐1 at 25°C, showed that the survival duration was not significantly increased in the presence of low concentrations (3 and ...

Study of viral and bacterial indicators in cockles and mussels

Abstract 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.

Comparative study of the behaviour of poliovirus in sterile seawater using RT-PCR and cell culture

Abstract Survival of poliovirus 1 was determined in sterile seawater at different salinity levels by detection of viral RNA by RT-PCR and comparison with tissue culture infectivity assay. Salinity appeared to have little influence on the behaviour of infectious particles: times necessary to obtain negative results by cell culture were not statistically different for the three salinities tested. Viral RNA was always detected by RT-PCR showing that in sterile medium viral particles can persist in a noninfectious form.

Detection of hepatitis a virus in wild shellfish

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.