A Portable Virus Concentrator for Use in the Field
125
The salts are solubilized in the field using the same water to be tested for viruses. This is
done as follows. Five gallons of water are passed through the clarification system
described above, and then through a 250 gram mixture of demineralizer resin plus
activated charcoal contained in a column equipped with QDs. Filtered water is collected
in the tank, and MgCl 2 and phenol red added. Mixing of the two reagents is performed by
sealing the tank with the cover, and vigorously bubbling nitrogen into the "outlet" of the
tank.
RESULTS
Virus recovery. The portable virus concentrating system was used to detect a small
amount of virus added to tap water. Instead of adding virus to a large volume of water in
expensive containers, virus was added to 300 gallons of running tap water. The portable
virus concentrator was connected to tap water (50 psi) into which virus, magnesium
chloride, phenol red and sodium thiosulfate were injected from the 5-gallon pressure
vessel, so that a final concentration in the running tap water was 0.75 PFU/liter, 0.04 M
MgCl 2 , 0.0004% phenol red, and 10 ppm thiosulfate. The experimental procedures follow
and the results are shown in Fig. 4.
To 5 gallons of clarified and demineralized tap water in the pressure vessel on the
portable virus concentrator, 16,000 grams of MgCl 2 , 8 grams of phenol red and 20 grams
of sodium thiosulfate were added to give final concentrations of 4 M MgCl 2 , 0.04% dye
and 1,000 ppm thiosulfate. Poliovirus was diluted in physiological saline at 10"
6 and
added to this treated water. Running tap water at 50 psi at a flow rate of 300 GPH was
passed through the portable virus concentrator (5 and 1 μ polyester filters, 1 μ treated
cotton filter, through the mixer and then through a fibreglass K-27 virus adsorbent). The
treated water in the pressure vessel was metered into the running tap water at a dilution
of 1:100 using the metering device and the sight glass as a monitor. After 300 gallons
passed the flow meter, the filter system was emptied of residual water as described in the
Methods section. The pressure vessel still contained 2 gallons of virus-salt-dye-thiosulfate
mixture, indicating that the injection of this material at 1:100 dilution was quite
accurate. Virus was eluted off the fibreglass membrane and the fibreglass eluate was
collected, acidified and treated with MgCl 2 as described. This eluate was passed through
the virus reconcentrator (cellulose membrane) and the virus concentrated on the
membrane was eluted in a 5 ml volume.
After the virus had been added to the mixture of salt-dye-thiosulfate in the 5 gallon
tank, it was too dilute to detect. Assay of the input virus indicated that a total of 1500
PFU had been added to the 5 gallons of fluid. In the test 3 gallons of
virus-salt-dye-thiosulfate mixture was injected into 300 gallons of running tap water.
Thus, only 900 PFU had been injected into the running tap water. Virus was eluted from
the virus adsorbent (fibreglass filter) with 1000 ml pH 11.5 eluent, and the eluate was
neutralized and MgCl 2 added as described above. Assay of a 1 ml sample of this eluate
failed to detect any virus, which was expected, since there could be a maximum of 900
PFU present in the 1600 ml of neutralized eluate. However, when the virus was
reconcentrated and eluted from the cellulose membrane into a final volume of 10 ml, an
average of 7 PFU/0.1 ml was detected, evidencing a total of 700 PFU in the total
concentrate, or 78% recovery. The experiment was repeated on another day with
essentially the same results.
125
The salts are solubilized in the field using the same water to be tested for viruses. This is
done as follows. Five gallons of water are passed through the clarification system
described above, and then through a 250 gram mixture of demineralizer resin plus
activated charcoal contained in a column equipped with QDs. Filtered water is collected
in the tank, and MgCl 2 and phenol red added. Mixing of the two reagents is performed by
sealing the tank with the cover, and vigorously bubbling nitrogen into the "outlet" of the
tank.
RESULTS
Virus recovery. The portable virus concentrating system was used to detect a small
amount of virus added to tap water. Instead of adding virus to a large volume of water in
expensive containers, virus was added to 300 gallons of running tap water. The portable
virus concentrator was connected to tap water (50 psi) into which virus, magnesium
chloride, phenol red and sodium thiosulfate were injected from the 5-gallon pressure
vessel, so that a final concentration in the running tap water was 0.75 PFU/liter, 0.04 M
MgCl 2 , 0.0004% phenol red, and 10 ppm thiosulfate. The experimental procedures follow
and the results are shown in Fig. 4.
To 5 gallons of clarified and demineralized tap water in the pressure vessel on the
portable virus concentrator, 16,000 grams of MgCl 2 , 8 grams of phenol red and 20 grams
of sodium thiosulfate were added to give final concentrations of 4 M MgCl 2 , 0.04% dye
and 1,000 ppm thiosulfate. Poliovirus was diluted in physiological saline at 10"
6 and
added to this treated water. Running tap water at 50 psi at a flow rate of 300 GPH was
passed through the portable virus concentrator (5 and 1 μ polyester filters, 1 μ treated
cotton filter, through the mixer and then through a fibreglass K-27 virus adsorbent). The
treated water in the pressure vessel was metered into the running tap water at a dilution
of 1:100 using the metering device and the sight glass as a monitor. After 300 gallons
passed the flow meter, the filter system was emptied of residual water as described in the
Methods section. The pressure vessel still contained 2 gallons of virus-salt-dye-thiosulfate
mixture, indicating that the injection of this material at 1:100 dilution was quite
accurate. Virus was eluted off the fibreglass membrane and the fibreglass eluate was
collected, acidified and treated with MgCl 2 as described. This eluate was passed through
the virus reconcentrator (cellulose membrane) and the virus concentrated on the
membrane was eluted in a 5 ml volume.
After the virus had been added to the mixture of salt-dye-thiosulfate in the 5 gallon
tank, it was too dilute to detect. Assay of the input virus indicated that a total of 1500
PFU had been added to the 5 gallons of fluid. In the test 3 gallons of
virus-salt-dye-thiosulfate mixture was injected into 300 gallons of running tap water.
Thus, only 900 PFU had been injected into the running tap water. Virus was eluted from
the virus adsorbent (fibreglass filter) with 1000 ml pH 11.5 eluent, and the eluate was
neutralized and MgCl 2 added as described above. Assay of a 1 ml sample of this eluate
failed to detect any virus, which was expected, since there could be a maximum of 900
PFU present in the 1600 ml of neutralized eluate. However, when the virus was
reconcentrated and eluted from the cellulose membrane into a final volume of 10 ml, an
average of 7 PFU/0.1 ml was detected, evidencing a total of 700 PFU in the total
concentrate, or 78% recovery. The experiment was repeated on another day with
essentially the same results.