INTERFERENCE BETWEEN THE INFLUENZA VIRUSES : II. THE EFFECT OF VIRUS RENDERED NON-INFECTIVE BY ULTRAVIOLET RADIATION UPON THE MULTIPLICATION OF INFLUENZA VIRUSES IN THE CHICK EMBRYO.

Influenza A or influenza B virus rendered non-infective by ultraviolet radiation was found to be capable of producing interference with the multiplication of active influenza viruses in the chick embryo. Certain temporal and quantitative relationships affecting the interference phenomenon with this host-virus system were studied. An hypothesis of the mechanism of interference between the influenza viruses is proposed and discussed.

INTERFERENCE BETWEEN THE INFLUENZA VIRUSES : I. THE EFFECT OF ACTIVE VIRUS UPON THE MULTIPLICATION OF INFLUENZA VIRUSES IN THE CHICK EMBRYO.

Reciprocal interference between influenza A, influenza B, and swine influenza viruses has been demonstrated in the chick embryo. Certain temporal and quantitative factors which influence the production of interference in this host-virus system have been studied. The implications of these observations in relation to the mechanism by which interference is produced are discussed.

IMMUNOLOGICAL RELATIONSHIPS AMONG CENTRAL NERVOUS SYSTEM VIRUSES.

From observations carried out with the viruses of Russian spring-summer encephalitis, louping ill, W.E.E.

THE EFFECT OF SOME CHEMICALS ON PURIFIED INFLUENZA VIRUS.

A study was made of the effect of 0.05 and 0.5 N solutions of 20 different chemicals on the activity of purified PR8 influenza virus in 0.

THE STABILITY OF INFLUENZA VIRUS IN THE PRESENCE OF SALTS.

The stability of centrifugally purified PR8 influenza virus at pH 7 in 0.001, 0.01, 0.

THE SIZE OF INFLUENZA VIRUS.

The sedimentation behavior of influenza virus in dilute solutions of electrolyte was found to be quite variable. At times the virus activity appeared to sediment at a rate comparable with that of particles about 80 to 120 mmicro in diameter, at other times at a rate comparable with that of particles about 10 mmicro in diameter, and at still other times the bulk of the activity appeared to sediment at a rate comparable with that of the larger particles and the residual activity at a rate comparable with that of the smaller particles. However, in the presence of a sucrose density gradient, the virus activity was always found to sediment with a rate comparable to that of particles about 80 to 120 mmicro in diameter; hence it appeared that the variable sedimentation behavior in dilute electrolyte solution was due to convection or mechanical disturbances during centrifugation.

AN EVALUATION OF METHODS FOR THE CONCENTRATION AND PURIFICATION OF INFLUENZA VIRUS.

The concentration and purification of influenza virus by means of differential centrifugation in a vacuum type centrifuge, by adsorption on and elution from adult chicken red cells, by elution of the precipitate formed on freezing and thawing of allantoic fluid, by adsorption on and elution from embryonic chick red cells, and by combinations of the first method with each of the three succeeding methods, have been studied. Over-all yields of virus of about 50 to 70 per cent were obtained by these methods and combinations of methods except for somewhat lower yields when adsorption on and elution from adult chicken red cells was employed. However, the purified products obtained by methods involving only the use of red cells or the freezing and thawing technique were found to contain about 80 per cent of non-virus protein.

THE MOUSE INFECTIVITY TITRATION OF INFLUENZA VIRUS.

A study has been made to establish the statistical significance of results obtained in mouse infectivity titrations of influenza virus. Five titrations, each composed of five replicas, were carried out and 50 per cent end points were calculated for each titration. Three criteria for evaluating the end points were employed, namely, the presence or absence of pulmonary lesions, the occurrence of death, and a weighted composite taking into account both the extent of lung consolidation and the occurrence of death.

QUANTITATIVE ASPECTS OF THE RED BLOOD CELL AGGLUTINATION TEST FOR INFLUENZA VIRUS.

A detailed study has been made of the nature of the variables inherent in the chicken red cell agglutination test for influenza virus in an effort to obtain a method of measurement of biological activity of sufficient accuracy that it might be employed as a reliable index of chemical purity of preparations of the virus. It was found that the temperature at which the test is conducted has a marked effect on the titer, whereas within the range of pH 6-8 the pH has a negligible effect. It was also found that a variation in results may be encountered due to a variation in the specific behavior of red cells from different chickens and to an instability of the red cells themselves.

A STUDY OF CONDITIONS FOR THE OPTIMUM PRODUCTION OF PR8 INFLUENZA VIRUS IN CHICK EMBRYOS.

In order to determine the conditions for the optimum production of PR8 influenza virus in chick embryos, a study has been made of the róles of concentration of virus in the inoculum, temperature of incubation of infected embryos, length of time of incubation of infected embryos, and age of embryos at the time of inoculation. Relative amounts of virus in different preparations were measured indirectly by means of determinations of chicken red blood cell agglutination titers. Frozen infectious allantoic fluid which produced infection in chick embryos at a maximum dilution of 10(-7) was employed as a stock inoculum.

A VIRUS CAUSING PNEUMONIA IN CATS AND PRODUCING ELEMENTARY BODIES.

From a contagious respiratory disease of cats an agent has been transmitted to mice, rabbits, guinea pigs, hamsters, and embryonated eggs. When inoculated intranasally into cats, it produces a disease like that seen in the naturally infected animals. Parenteral injection causes only a mild fever.

STUDIES ON THE CHEMICAL NATURE OF THE SUBSTANCE INDUCING TRANSFORMATION OF PNEUMOCOCCAL TYPES : INDUCTION OF TRANSFORMATION BY A DESOXYRIBONUCLEIC ACID FRACTION ISOLATED FROM PNEUMOCOCCUS TYPE III.

1. From Type III pneumococci a biologically active fraction has been isolated in highly purified form which in exceedingly minute amounts is capable under appropriate cultural conditions of inducing the transformation of unencapsulated R variants of Pneumococcus Type II into fully encapsulated cells of the same specific type as that of the heat-killed microorganisms from which the inducing material was recovered. 2.

STUDIES ON THE ANTIGENIC COMPOSITION OF GROUP A HEMOLYTIC STREPTOCOCCI : IV. RELATED T BUT DISTINCT M ANTIGENS IN TYPES 15, 17, 19, 23, 30, AND IN TYPES 4, 24, 26, 28, 29, 46. IDENTIFICATION BY SLIDE AGGLUTINATION.

1. The occurrence of closely related T antigens in the series composed of types 15, 17, 19, 23, and 30 accounts for most of the cross reactions observed among these types. Similarly T antigens, unrelated to the first series but mutually related, occur in a second series comprising types 4, 24, 26, 28, 29, and 46.

STUDIES ON THE ANTIGENIC COMPOSITION OF GROUP A HEMOLYTIC STREPTOCOCCI : III. TYPES WITH SEROLOGICALLY IDENTICAL M BUT DISTINCT T ANTIGENS: TYPES 10 AND 12.

1. In this study a series of experiments showing the antigenic relationship of type 10 and type 12 group A hemolytic streptococci is reported. Agglutinin, precipitin, and passive protection tests with unabsorbed and reciprocally absorbed antisera were employed to show that representative type 10 and 12 strains contain serologically identical M antigens but unrelated type-specific T antigens.

STUDIES ON THE ANTIGENIC COMPOSITION OF GROUP A HEMOLYTIC STREPTOCOCCI : II. THE OCCURRENCE OF STRAINS IN A GIVEN TYPE CONTAINING M BUT NO T ANTIGEN.

1. Group A hemolytic streptococci have been described which do not agglutinate in anti-T serum because they lack T antigen. 2.

RELATIONSHIP OF THE VIRUS OF LOUPING ILL IN SHEEP AND THE VIRUS OF RUSSIAN SPRING-SUMMER ENCEPHALITIS IN MAN.

An experimental study of three strains of Russian spring-summer encephalitis virus and one of louping ill virus has yielded the following results:- 1. The sera of mice hyperimmunized to the viruses of Russian encephalitis and louping ill respectively have produced complement fixation with both antigens in almost precisely the same titer. 2.

SELECTIVE REVERSIBLE INHIBITION OF MICROBIAL GROWTH WITH PYRITHIAMINE.

Growth of many microbial species was inhibited by pyrithiamine, the pyridine analog of thiamine. Growth of many other species was not influenced. In a series of bacteria, yeasts, and molds, it was found that inhibition of growth occurred only in those in which growth was stimulated by thiamine or its component pyrimidine and thiazole portions.

STUDIES ON THE ANTIGENIC COMPOSITION OF GROUP A HEMOLYTIC STREPTOCOCCI : I. EFFECTS OF PROTEOLYTIC ENZYMES ON STREPTOCOCCAL CELLS.

1. Proteolytic enzymes destroy the type-specific M antigen of group A hemolytic streptococci not only when the M substance is contained in cell-free extracts but also when it is a component of the living cell. 2.

NEUTRALIZING AND COMPLEMENT-FIXING ANTIBODY PRODUCTION AND RESISTANCE FOLLOWING VACCINATION IN EXPERIMENTAL ENCEPHALITIS INFECTIONS.

In mice vaccinated subcutaneously with different doses of virulent W.E.E.

A FILTERABLE VIRUS CAUSING ENTERITIS AND PNEUMONIA IN CALVES.

An infectious disease of calves has been described which is characterized by fever, diarrhea, and pneumonia, followed soon by recovery. On autopsy of animals killed at the height of the disease, there is found a catarrhal enteritis and a bronchopneumonia that is usually confined to the anterior lobes of the lungs. From this disease an agent has been secured by the serial inoculation of lung extracts that produces a pneumonia in white mice.

A MODEL OF THE POTASSIUM EFFECT.

The protoplasm of certain cells is able to distinguish electrically between K(+) and Na(+). This has been called the potassium effect. This is illustrated by experiments with Nitella.

STUDIES OF THE INNER AND OUTER PROTOPLASMIC SURFACES OF LARGE PLANT CELLS : I. PLASMOLYSIS DUE TO SALTS.

In Nitella, Chara, Hydrodictyon, and Valonia the inner and outer non-aqueous protoplasmic surface layers can be separated by certain plasmolytic agents which penetrate the outer surface more rapidly than the inner and hence raise the osmotic pressure of the protoplasm lying between them and cause it to increase in thickness by taking up water from the central vacuole. We may therefore conclude that the two surfaces differ. This idea is confirmed by earlier electrical measurements which show that when sap is placed outside the cell the chain See PDF for Structure produces an E.

THE YIELD OF RABIES VIRUS IN THE CHICK EMBRYO.

Rabies virus was inoculated intracerebrally in 8 day old chick embryos and the virus activity of pools of embryos titered after incubation at 35-36 degrees C. for different lengths of time. The virus reached a titer of 10(-5.

PRODUCTION OF A SCURVY-LIKE CONDITION BY FEEDING OF A COMPOUND STRUCTURALLY RELATED TO ASCORBIC ACID.

The feeding of glucoascorbic acid, an analog of ascorbic acid, to mice and cotton rats caused the production of a condition exhibiting many of the changes characteristic of scurvy as seen in susceptible species. The condition was not prevented or cured by ascorbic acid, but was cured by removal of the glucoascorbic acid from the ration. The condition was produced in mice fed a highly purified ration.