A method of treating asbestos filter pads for virus filtration

Our plain-English summary of A method of treating asbestos filter pads for virus filtration, by N.S. Hyslop (Nature, 1961).

The study

• Author: N.S. Hyslop
• Journal: Nature
• Published: 1961;191:305-7
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This 1961 laboratory report was not about the health effects of asbestos. It concerned asbestos filter pads used to filter virus suspensions. These pads can lose much of the virus because the virus sticks to the pad. The author tested whether treating the pads beforehand with sodium alginate, a substance prepared from seaweed, reduced these losses better than gelatin. Pads were treated with solutions of either substance at 0.0025 to 0.06 per cent. They were then used to filter vesicular stomatitis virus and foot-and-mouth disease virus, and the amount of virus was measured by tests in mice. With untreated pads, vesicular stomatitis virus losses in some cases exceeded 5 log units. Stronger solutions reduced losses only down to a floor: 1.95 log units with gelatin and 0.9 with sodium alginate. Gelatin-treated pads always lost more virus than pads treated with the same concentration of alginate. Foot-and-mouth disease virus losses were smaller, with lowest values of about 0.15 log unit (alginate) and 0.43 log unit (gelatin). The author concluded that 0.04 to 0.05 per cent sodium alginate was a valuable means of minimizing these losses. The author noted that the virus preparations used were relatively crude.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: laboratory experiment comparing filter pre-treatments
• Who was studied: No people were studied. The experiments used asbestos filter pads (3.0 cm diameter, E.K. equivalent grade) to filter suspensions of vesicular stomatitis virus (Indiana type) and foot-and-mouth disease virus (types O, C and Asia 1). Virus amounts were measured by titration in young mice of the Pirbright 'P' strain.
• Exposure: Pre-treatment of asbestos filter pads with sodium alginate or gelatin solutions at concentrations from 0.0025 to 0.06 per cent, compared with untreated pads washed with buffer only. The asbestos fiber type is not stated.
• Main results:
  • With pads only washed with phosphate buffer, losses of vesicular stomatitis virus during filtration in some cases exceeded 5 log units.
  • For vesicular stomatitis virus, increasing concentrations reduced losses only down to critical values of 1.95 log units (gelatin) and 0.9 log units (sodium alginate).
  • For vesicular stomatitis virus, losses with gelatin-treated pads were always greater than with pads treated with the same concentration of sodium alginate.
  • Foot-and-mouth disease virus losses, through treated or untreated pads, were considerably less than vesicular stomatitis virus losses.
  • For foot-and-mouth disease virus, losses could not be reduced below about 0.15 log unit with sodium alginate or 0.43 log unit with gelatin.
• The authors' conclusion: The author concluded that pre-treating asbestos filter pads with 0.04 to 0.05 per cent sodium alginate solutions is a valuable means of minimizing adsorption losses when filtering virus suspensions.
• Limitations the authors state:
  • The virus suspensions were relatively crude preparations, so the results do not necessarily apply to highly purified virus.
  • The sodium alginate preparation contained a trace of protein. The author attributed the effect principally to the alginate itself.

Topics

Medical terms in this study, explained in our Lexicon: Filter pad.

Related studies

• Toxicity of cell culture medium due to filtration through asbestos pads — W. House (1964)
• Detection of virus in water: sensitivity of the tentative standard method for drinking water — W.F. Hill, W. Jakubowski, et al. (1976)
• The influence of external aerodymanic factors on the measurement of the airborne concentration of asbestos fibres by the membrane filter method — A.M. Johnston, A.D. Jones, et al. (1982)
• Comparison of a fibrous aerosol monitor (FAM) with the membrane filter method for measuring airborne asbestos concentrations — P.J. Iles, T. Shenton-Taylor (1986)
• Sample preparation method for visualization of nanoparticulate captured on mixed cellulose ester filter media by enhanced darkfield microscopy and hyperspectral imaging — N.M. Neu-Baker, A.C. Eastlake, et al. (2019)
• A comparison of fibre counting stopping rules in the application of the membrane filter method — N.P. Crawford, W.M. Maclaren, et al. (1987)

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