Elimination and monitoring of viruses

Team
Thomas Egli, Frederik Hammes, Iris Huelshoff

Goal
To develop PCR and flow-cytometric based methods to determine the virus particle elimination efficiency of different barriers used in drinking water production.

Description
Membrane filtration allows eliminating even small particles such as viruses from drinking water. The analysis of viruses, in particular those that are human pathogens, however, is tedious. The detection of virus-specific genetic sequences using (quantitative) PCR is a technique that is presently used with good sensitivity. It allows the quantification of selected viruses. A second method that is increasingly applied is the detection of virus particles using flow cytometry. This method is based on the staining of viral particles with DNA/RNA specific fluorescent dyes and has been applied so far for environmental, particularly marine samples. It allows the unspecific detection of viral particles and seems to give a good estimate of the number of total viruses present in a sample. However, this method is not yet applied widely.

To evaluate the virus (bacterial) particle elimination efficiency of different barriers (including membrane filters) and the integrity of membrane filtration processes we focus on the following aspects:

- First, the molecular tools (PCR) necessary for the detection of viral genetic material have to be established. Access to this know-how will be obtained through collaboration with Laboratory Spiez where good knowledge available on detection of viruses in drinking water. Selected environmentally ubiquitous bacteriophages and human/animal pathogenic viruses will be used as model systems.

- Flow cytometry for the detection of virus particles will be tested as a tool to quantify total virus particles. The possible combination of flow cytometry with fluorescent antibodies specific for capsule proteins of specific viruses will also be investigated.