Virus aggregation as the cause of the non-neutralizable persistent fraction.

The non-neutralizable or persistent fraction of virus populations has been found to be caused by aggregated virus. Detailed investigation was performed with the prototype strain of echovirus type 4 (Pesascek), as this virus is notorious for its large non-neutralizable fraction. When Pesascek virus was clarified by low-speed centrifugation, homologous antiserum hardly neutralized the virus.

Concentration of enteroviruses on membrane filters.

Enteroviruses can be made to adsorb or to pass through membrane filters by manipulation of the suspending medium. Salts facilitate virus adsorption, but membrane-coating components (MCC) interfere. Because cells release MCC into the culture medium during viral growth, MCC must be removed before virus can be adsorbed to membranes.

Physical assay and growth cycle studies of a defective adeno-satellite virus.

Electron microscopic particle counting of the defective adeno-satellite virus (ASV), by use of pseudoreplication and negative staining with phosphotungstic acid, was shown to be a reproducible quantitative assay procedure. Particles of satellite type 4 that were counted in fluids from infected cultures had the same morphology as particles that banded at a buoyant density of 1.43 g/cc in cesium chloride.

WHO collaborative study on the sero-epidemiology of rubella.

Under the auspices of WHO an investigation was made by 9 laboratories in different parts of the world on the distribution of rubella antibodies in girls and women of child-bearing age. In the first part of the study the objective was to determine the reliability and reproducibility of the tests employed. It was found that there were no significant differences in the variability of the titres obtained in different laboratories when the results were compared with those obtained by repeatedly testing the same sera in one laboratory.

Concentration of viruses from sewage by adsorption on millipore membranes.

The authors describe a relatively simple membrane-adsorption method for the efficient concentration of viruses from sewage. Sewage, first freed of bacteria by filtration through membranes under conditions that permit virus to pass freely, is then treated with anion resins to remove organic components that adsorb to Millipore membranes and prevent virus adsorption. The salt concentration of the resin filtrates is increased with MgCl(2) to enhance virus adsorption to membranes.

Replication of adenovirus type 7 in monkey cells: a new determinant and its transfer to adenovirus type 2.

A strain of human adenovirus type 7, adapted to replication in green-monkey kidney cells, requires the interaction of two particles to initiate plaque formation in the simian cells. One particle is a true adenovirion. The second, apparently defective, consists of a genome carrying amonkey-adapting component in an adenovirus capsid; this genome does not express known SV40 determinants.

Detection of biologically active adenovirions unable to plaque in human cells.

Butel, Janet S. (Baylor University College of Medicine, Houston, Tex.), Joseph L.

Effects of pancreatin on the growth of reovirus.

Wallis, Craig (Baylor University College of Medicine, Houston, Tex.), Joseph L. Melnick, and Fred Rapp.