An electron microscopic study of moderate and virulent virus-cell interactions of the parainfluenza virus SV5

The membrane structure of lipid-containing viruses.

The survival rate, p , of a measured inoculum of Staph. aureus in a standard volume of denbrinated blood, is a reliable quantitative measure of the bactericidal power of blood. The number of viable organisms in the inoculum and in the blood-bacterium mixture may be estimated with the necessary accuracy by counts of colonies developing from measured volumes of the fluids let fall on to the surface of solid media. Fildes' agar was the most suitable medium for this surface-viable count, and was selected on the basis of four criteria; of the media tested it yielded the highest counts, and the counts conformed most closely to a Poisson series; and on it the mean colony size was maximum, and the coefficient of variation of colony size was minimum. On this medium, the close conformity of the separate count values to a Poisson series enabled the standard error of the survival rate to be determined from a simplification of the general expression for the standard error of a ratio. The number of colonies growing from a sample of a blood-bacterium mixture may be reduced, not by killing of the individual cocci, but as a result of their aggregation either by agglutinins in the blood, or in the cytoplasm of leucocytes that are phagocytic but not bactericidal. It appears that these mechanisms are unlikely to operate in blood-bacterium mixture containing relatively few organisms; in such mixtures the survival rate is a reflexion of the killing power only. The immunological significance of p has not been investigated, but the range of values for healthy human adults differs significantly from that for sufferers from chronic staphylococcal infection. Moreover, by the technique employed differences may be detected between individual values of p that cannot reasonably be attributed to technical or sampling errors.

The Estimation of the Bactericidal Power of the Blood. With a Note by J. O. IRWIN.

Seven strains of influenza A2 virus were serially passed in the chick embryo, and morphological characteristics of the passages were examined in the electron microscope. With serial passage there was a change from a prominently filamentous appearance in early passages to an almost entirely spherical appearance in later passages. The number of passages required for the conversion to spherical morphology varied with different strains. The filament-sphere variation was found to be independent of the properties which differentiate "+" and "-" influenza A2 virus particles, and both highly filamentous and spherical populations of "+" and of "-" virus particles were obtained. The usefulness of these pairs of independent markers for genetic studies is discussed.

/pdf/studies-of-two-kinds-of-virus-particles-which-comprise-wxyn0nxai9.pdf

Studies of two kinds of virus particles which comprise influenza a2 virus strains : iii. morphological characteristics: independence of morphological and functional traits

Two kinds of virus particles have been found in varying proportions in influenza A2 strains isolated during the 1957 pandemic. Pure populations of the different particles were obtained, and these substrains were genetically stable on serial passage in the chick embryo. The two virus particles differ markedly in several biological properties though they are antigenically similar. One kind of particle, designated "+," is relatively sensitive to specific antibody, is highly sensitive to inhibition by serum inhibitors and urinary mucoprotein, fails to elute or elutes very slowly from human erythrocytes, and is capable of agglutinating erythrocytes treated extensively with V. cholerae filtrate. The other particle, designated "-," is relatively insensitive to antibodies and urinary mucoprotein, completely insensitive to serum inhibitors, elutes rapidly from erythrocytes, and can agglutinate erythrocytes treated extensively with V. cholerae filtrate. Both "+" and "-" particles destroy virus receptors on urinary mucoprotein. The relative proportions of these two particles determine the characteristics of parent strains in reactions with specific antibody, mucoprotein inhibitors, and erythrocytes. The "+" and "-" particles with several easily identifiable markers are well suited for genetic studies.

/pdf/studies-of-two-kinds-of-virus-particles-which-comprise-3hasaqi69b.pdf

Studies of two kinds of virus particles which comprise influenza a2 virus strains : i. characterization of stable homogeneous substrains in reactions with specific antibody, mucoprotein inhibitors, and erythrocytes

Influenza; a study of four virus strains isolated in 1951.

SUMMARY: A modification of the Hirst&Pickels photoelectric densitometer and its application to work on influenza virus haemagglutination are described. The methods used are believed to reduce to a minimum the inherent margin of error of virus and serum antibody assays based upon the haemagglutination reaction. In order to make full use of data thus obtained precise assessment of the significance of differences of titre is essential, and for this purpose two simple statistical tests have been applied and their application illustrated by an example.

Influenza Haemagglutination An Evaluation of the Photoelectric Titration Method

A specific virus-antibody flocculation reaction with poliomyelitis viruses.

Poliomyelitis-virus flocculation by a micro-method

EXPERIMENTS designed to unmask deeper antigenic components of influenza viruses by heat degradation of their type-specific surface antigens yielded evidence of relationship between virus types A and B based upon their possession of a common antigen. The antigen concerned was found to be almost indistinguishable from a component of the host tissues (chick embryo) in which the viruses were propagated, which at once aroused suspicion that it might be merely contaminant material adsorbed on the virus. The presence of an antigenic component in purified virus preparations of types A and B, which was also demonstrable in normal allantoic fluids, was first reported by Knight1, who used a precipitation test with hyper-immune rabbit sera and viruses purified by differential centrifugation. It has been pointed out that reliance upon centrifugation for virus purification is open to the objection that centrifugation merely selects particle size and density, and it has been shown by Knight2 himself that the normal allantoic fluid antigen is of similar size to the influenza viruses.

A host-protein component of influenza viruses.

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