Bernard P. Sagik

Viral association with suspended solids

Abstract Laboratory models and field sewage samples were used to study viral association with particulates in suspension. Poliovirus and coliphages T2, T7 and f2 were tested for their adsorption to and elution from both organic and inorganic suspended solids at a variety of pH values and in both the presence and absence of a divalent cation. The results indicate that no one of the viruses tested can be used to describe a general pattern of adsorption. T2 and f2 readily associated with the clays used in the presence of divalent cation, while T7 and poliovirus adsorbed equally well to both organic and inorganic particulates. All viruses varied in the degree to which they associated with naturally-occurring suspended solids in primary and final sewage effluents; maximal association occurred at the pH extremes of 4.0 and 10.0 for all systems. Regardless of the conditions used to effect adsorption, all viruses tested, with the exception of f2, were infective by plaque assay in their adsorbed form. These data suggest that no one coliphage system can acceptably model the behavior of poliovirus in laboratory or field conditions. Furthermore, the results reaffirm and broaden the findings that viruses associated with suspended particulates are infective. Therefore, any system used to monitor virus levels in the environment must adequately account not only for free virus, but also for those which are solids-associated.

Virus rejection by the reverse osmosis-ultrafiltration processes

Abstract : Rejection of viruses by commercial grade asymmetrical cellulose acetate membranes commonly used in the ultrafiltration and reverse osmosis processes was evaluated. Various concentrations of coliphage T2 and poliovirus were innoculated in the feed water of a bench scale ultrafiltration-reverse osmosis unit and virus concentrations in the produce were determined. The insoluble polyelectrolyte technique for concentrating extremely low levels of virus was modified and standardized for use in the study. Membrane penetration studies indicated that limited numbers of virus passed the membranes. The penetration of viruses may be attributable to the presence of random areas of imperfect crosslinkage of the cellulose acetate in the dense layer of the membrane. Despite limited virus penetration, all of the cellulose acetate membranes used in this study rejected an extremely high percentage of the viruses and provided a product water of excellent quality.

The Survival of EK1 and EK2 Systems in Sewage Treatment Plant Models

In March 1977 the National Academy of Sciences (USA) convened a Forum on Research with Recombinant DNA. It was clear to participants that this potentially was an opportunity to affect national science policy. In trying to assess the benefits and risks inherent in recombinant DNA technology, some argued the risks were not different than any in the microbiology laboratory; others warned that such research was the first step towards the manipulation of human genetics, that it could contaminate the biosphere irrevocably.

The Effect of Membrane-Active Agents on Sindbis Virus Morphogenesis

In chicken cells infected by Sindbis virus and exposed to a variety of membrane-active compounds, virus release was inhibited. In infected cells exposed to antiserum directed against the virion glycoproteins E1 or E2, retinol, cortisone, Pb++ or insulin, the processing of two Sindbis virus precursor polypeptides which lead to the formation of virion polypeptides was inhibited. The B-protein, which is the precursor to both envelope proteins, accumulated in cells treated by these compounds. This precursor is generally not detected in chicken cells, presumably because it is processed rapidly. The cleavage of the precursor PE2 to the envelope glycoprotein E2 was also inhibited. E2 was also absent in cells exposed to menadione or to antiserum prepared against uninfected chicken cells. Since each of the compounds tested interfered with Sindbis virus polypeptide cleavage, despite their diverse mechanisms of action, it suggests that perturbation of normal membrane fluidity can interfere with Sindbis virus budding.