118
Discussion
2. BERG, G. "Integrated Approach to Problem of Viruses in Water." San. Engrg. Div., ASCE,
97:SA6:867-83, 1971.
3. BERG, G., DAHLING, D.R.. BERMAN, D. In manuscript.
Reply
The development of equipment and methods has been based upon the three features referred to
by the discussor. Now the equipment and methods have been shown to function satisfactorily,
attention can be focused upon recovery of small numbers under the exacting field conditions
encountered in coastal Texas waters.
Professor Malina
The virus concentrator can be used only in clean waters because the presence of soil particulates in
dirty waters would lead to adsorption of virus to their surface, and virus would be removed from the
water sample when soil particulates were removed during clarification.
Reply
The data presented refutes this contention. As shown clearly in the slides presented, large amounts
of sedimentary materials including clays, silts and sundry debris failed to cause virus retention upon
clarifying filters. Furthermore as shown in the data presented, no evidence for virus retention by such
adsorption could be found in a lengthy series of laboratory tests.
Ebba Lund, Denmark
Did you look for viruses in the suspended matter discarded? I find the virus content of samples
bound totally or partly to material spun down at low speed centrifugation, elimination at pH 9
removes only a part of the virus.
Reply
No
In reply to a question by Dr. Lund, we have found that enteroviruses are more readily eluted at pH
11 to 12 than at pH 9. Glycine buffer should be used and the eluate should be quickly neutralized.
Discussion
2. BERG, G. "Integrated Approach to Problem of Viruses in Water." San. Engrg. Div., ASCE,
97:SA6:867-83, 1971.
3. BERG, G., DAHLING, D.R.. BERMAN, D. In manuscript.
Reply
The development of equipment and methods has been based upon the three features referred to
by the discussor. Now the equipment and methods have been shown to function satisfactorily,
attention can be focused upon recovery of small numbers under the exacting field conditions
encountered in coastal Texas waters.
Professor Malina
The virus concentrator can be used only in clean waters because the presence of soil particulates in
dirty waters would lead to adsorption of virus to their surface, and virus would be removed from the
water sample when soil particulates were removed during clarification.
Reply
The data presented refutes this contention. As shown clearly in the slides presented, large amounts
of sedimentary materials including clays, silts and sundry debris failed to cause virus retention upon
clarifying filters. Furthermore as shown in the data presented, no evidence for virus retention by such
adsorption could be found in a lengthy series of laboratory tests.
Ebba Lund, Denmark
Did you look for viruses in the suspended matter discarded? I find the virus content of samples
bound totally or partly to material spun down at low speed centrifugation, elimination at pH 9
removes only a part of the virus.
Reply
No
In reply to a question by Dr. Lund, we have found that enteroviruses are more readily eluted at pH
11 to 12 than at pH 9. Glycine buffer should be used and the eluate should be quickly neutralized.