Ernest Kovács

Nucleases in the cerebrospinal fluid

Summary About 200 specimens were examinedfor nucleodepolymerase. DNA-se is not as frequently demonstrable in the CSF as RNA-se. In normal or neurologically normal samples no DNA-se was found, as a rule, but a small number of nonneurological cases showed a very moderate degree of activity. The majority of meningitis, syphilis, epilepsy, hydrocephalus, and concussion specimens exhibited DNA-se activity. The absence of this enzyme in CSFs of all clinical forms of poliomyelitis was striking. The other important finding was the relatively high depolymerase level found in some neurological and psychoneurosis samples.

Nucleases in the cerebrospinal fluid: III. Simultaneous determination of ribo- and desoxyribonuclease in the CSF of patients with poliomyelitis*

Summary Characteristic RNA-se and DNA-se patterns were observed in the CSF of poliomyelitis and other patients with virus disease. These patterns differ qualitatively and quantitatively from the majority of other specimens. The results are statistically significant. With quick methods the two nucleases can be demonstrated within forty minutes. The pathological importance of these findings is discussed.

Comparative Biochemical Studies on Normal and Poliomyelitis Infected Tissue Cultures. IV. Enzyme-changes in Host Cells

Summary 1. Marked changes in the activities of 9 enzyme systems were observed at the height of poliomyelitis infection in vitro. 2. The decrease of alkaline phosphatase, pentanucleotidase, simple nucleotidase, “acid”RNA-se and DNA-se is so marked, that this may serve as a quantitative measure of cytopathogenic effect of the poliomyelitis virus. 3. The bearing of these findings on cellular physiology and pathology is discussed, as a working hypothesis.

The Role of Heredity

This chapter describes the role of heredity in poliomyelitis. The genetic studies, on the analogy of phage research, have already been started in poliomyelitisresearch as well, for instance by examining the phenotypic mixing of Type I, II, and III of poliomyelitis viruses, administered to the same host cells. Hirst studied the effect of mixed infection with poliomyelitis, influenza, and NDV, which resulted in phenotypic mixing of polio- and NDV-viruses, but not in recombination. This type of initiative should be encouraged, because of the great importance of fact-finding on the heredity of human and experimental poliomyelitis infection. The valuable work of Puck and associates in the preparation of clonal mammalian cells with a variety of refined techniques, suitable for genetic and virological studies, should also be remembered. Similarly, Vogt and Dulbecco demonstrated the increased resistance of cloned HeLa cell subcultures to Type III (Leon) poliomyelitis virus. The resistant culture has come about through the selection of a pre-existing resistant variant from the S 3 population. On the other hand, Dunnebacke claimed that it is not the cell strains; however, the virus strains that determine the size of virus yield per cell.

Propagation of Mammalian Viruses in Protista. IV. Experimental Infection of C. albicans and S. Cerevisiae with Polyoma Virus

Summary Experimental infection of yeasts, C. albicans and S. cerevisiae with unadapted polyoma virus was carried out reproducibly under various experimental conditions, measured by increase in hemagglutination and infectivity during incubation. All important assays were repeated several times with similar positive results. Approximately 68-fold increase in HAU and approx 104 increase in PFU/system over the inoculum was observed with unadapted PyV, but this yield may be increased with adaptation and further technical refinements as will be published separately. The virus propagation brought about cell biological and population changes which were illustrated and discussed together with the significance and bearing of the primary infection of two different species of yeasts with an oncogenic virus. The courtesy of Dr. M. Williams of the Ontario Cancer Institute for the T strain of the PyV, Mr. G. Healy, Connaught Medical Research Laboratories, for the generous supply of media, Dr. D. B. W. Reid, Professor of Biometry, University of Toronto, for advice in statistical evaluation and Mr. J. Kovács for his technical help is gratefully acknowledged.

Propagation of mammalian viruses in Protista. III. Change in population densities, viability and multiplication of yeasts and tetrahymena experimentally infected with encephalomyo-carditis virus

Abstract Adsorption and presence of fluorochrome labelled Encephalomyocarditis (EMC) virus was visualized in the yeast, S. Cerevisiae f. and the Ciliate, T. pyriformis, g. (1). The multiplication of complete EMC particles and the resynthesis of Poliovirus from isolated infectious RNA was also demonstrated in Protista (2). The present report is concerned with the cytophathic effect (CPE) of the virus infection consisting of decrease in population densities, change in size, shape, viability and multiplication of Saccharomyces, Candida and Tetrahymena cells incubated with EMC. Further, mainly cytological aspects will be described separately (3).

Biochemical Aspects of Some Other Features of the Virus Problem

Virology is one of the many aspects of general and special cell physiology and pathology. The only common and acceptable analogy with bacteriology is that the bacteria are also exposed to the effect of their viruses. This chapter describes the morphological and biochemical features of the cancerous cells. There are many viruses that do not cause cell destruction but on the contrary cause hypertrophy and/or proliferation of the cells. Viruses causing tumors or leukemia were known long ago. The demonstration of the infectivity of nucleic acids extracted from various tumors by the phenol method brings tumor virus research in line with that of other viruses. Electron microscopy has extended the boundaries of cell morphology and the biology, presenting a large and complex dominion, where seemingly each cellular granule, although invisible by optical means, has its definite structure and function. The invisible pathogens, the viruses were seen for the first time because of their electron dense properties.

Facts and Speculations on the Biosynthesis of the Virus, a working Hypothesis of the Author

This chapter presents the facts and speculations on the biosynthesis of the virus. The macromolecules of the virus having lost their particulate state may become solubilized by RN-ases and proteases of the host cell. This facilitates their circulation in the viscous pulsating jelly of the protoplasm, ensuring that they are degraded further and metabolized or re-synthesized. If by the penetration of the macromolecular RNA some enzyme systems hydrolyzing poly- and oligonucleotides are inhibited, 30–40% of the polymerized molecule, the core of the RNA may survive and with this the resynthesis of the specific viral nucleic acid may be achieved. This core may serve as a template or a skeleton, to which first the missing mono- and oligonucleotides will be attached, then amino acids, through the specific activating enzyme systems. The rest of the nucleic acid may be self determining for the protein synthesis, deciding the attachment and the definite sequence of the amino acids. Peptide residues may still be intimately connected with the fragments of the original RNA, assuring the resynthesis of the specific virus nucleoprotein.

Biochemistry of Poliovirus Infection in Cells in Culture

This chapter presents the facets of biochemistry of poliovirus infection in cells in culture. It presents the biological and biochemical findings in this regard. In an experiment discussed in the chapter, the addition of insulin to tissue culture medium increases the poliomyehtis virus production that may be in accordance with the findings of Eagle and the conclusions of Becker that the glycolytic, rather than the oxidative processes, are important for the reproduction of poliomyelitis virus in human and monkey cells. Enzymatic aspects of the problem were not investigated by Likar. The hibernation of HeLa cells, meaning their exposure to suboptimal temperatures after infection, resulted in retardation of the appearance of the cytopathic effect; however, no pathology was observed in cells incubated at 4°C over 3 weeks. The biochemistry of this phenomenon was not investigated, though it seems to be connected with the lowering of the cell metabolism.

The Biochemical Concept of Poliomyelitis Virus Infection

This chapter presents the biochemical concept of poliomyelitis virus infection. The poliomyelitis virus infection is a new type of pathology, because of the invasion of a host by adapted, particulate macromolecules, or their nonparticulate derivatives, thus, by suborganismal pathogens, with all the biological and pathological consequences of this macromolecular intoxication. Its transmissibihty and the use of classical bacteriological methods cannot prejudice or determine further the particular state of virology, this different and special cell pathology. Virology has just a few traits in common with bacteriology, such as the bacteria are unicellular organisms and, thus, liable to their own virus pathologies and certain microorganisms causing infectious diseases. However, grafting of tumors or the transplantation procedures of normal tissues, the fecundation of ovum by the sperm, are transmissions, without being infections. The virologic process is an entirely different pathology from the bacteriological one. It is more or less intoxication by an invasive, adapted macromolecule, although this expression does not cope with the fact, that this chemical compound may be a quite normal, or almost normal genetic cell constituent, reproduced by physiological cell-mechanisms.