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Biomedical subjects

T J Wiktor

Publications and source records attributed to T J Wiktor.

88 records · Page 5Linked to original sources
PubMed1968

Hemagglutination by rabies virus.

Goose erythrocytes were agglutinated by five strains of rabies virus grown in monolayer cell cultures at pH 6.4 and at 0 to 4 C. Hemagglutination was not affected by the cell type in which the virus was grown. Prerequisites for occurrence of hemagglutination are absence of hemagglutination inhibitors (such as those contained in bovine serum) and a relatively high virus concentration (> 10(6) plaque-forming units of virus per ml). "Soluble" hemagglutinin was not present in crude preparations of extracellular virus. Treatment of purified preparations of extracellular virus with Tween 80 and ether did not result in release of a "soluble" hemagglutinin. The hemagglutinating property of extracellular virus seemed to be conditioned by the integrity of its coat. Preparations of infectious intracellular virus exhibited about 15 times lower hemagglutinating activity than extracellular virus. This decreased hemagglutinating activity did not seem to be caused by binding of hemagglutination inhibitors to the virus particles. Rabies virus can be quantitatively adsorbed onto and eluted from erythrocytes. Erythrocytes pretreated with rabies virus retained their ability to be agglutinated by the same virus strain. The reaction with rabies virus of erythrocytes treated with the receptor-destroying enzyme or KIO(4) was the same as that of nontreated erythrocytes. The hemagglutinating component of rabies virus, therefore, does not exhibit neuraminidase activity. Treatment of extracellular virus by various agents indicated that the hemagglutinating component consists of protein or lipoprotein. Sulfhydryl groups present in the viral hemagglutinin are essential for hemagglutination.

Animals↗
PubMed1968

Purification of rabies virus grown in tissue culture.

Extracellular rabies virus, grown in monolayer cultures of BHK21 cells in the presence of medium supplemented with bovine serum albumin, was purified by the following procedure. Virus was precipitated from infectious tissue culture fluid by zinc acetate and was resuspended in a solution of ethylenediaminetetraacetate. The suspension was filtered through a Sephadex column and was treated with ribonuclease and deoxyribonuclease. The virions were then pelleted by centrifugation at high speed and were resuspended in buffer solution. Banding of the virus by centrifugation in a sucrose density gradient was the final step in the purification procedure. Purified preparations contained bullet-shaped virus particles of variable length and little (up to 5%) contaminating host-cell material. Most of the virions were "complete", i.e., 180 nm long, but some virus particles were shorter. The length distribution of the virions was nonrandom. Shorter virions seemed to be noninfectious and showed markedly decreased hemagglutinating activity. The complement-fixing activity and the ribonucleic acid to protein ratio of the virions were not related to the length of the virus particles. Although the properties of extracellular and intracellular viruses were similar, the procedure was not suitable for purification of intracellular rabies virus.

Centrifugation, Density Gradient↗
PubMed1968

Present trends and the future in rabies research.

Until very recently, rabies research had made few notable advances since the time of Pasteur, but during the past few years the use of modern virological techniques has led to rapid progress in research on the rabies virus. This article summarizes the present state of knowledge of pathogenesis, immunology, cultivation in tissue culture, cell-virus relationships, and physicochemical properties of the virus.It is now possible, and opportune, to undertake the study of basic problems in the biology of rabies, which include the need for an improved method of post-exposure protection. Information gained from work on these problems should lead to important insights into other current problems of infectious processes such as "slow-virus" infections. The most promising directions of future research in rabies are enumerated and suggestions are made on the experimental techniques that might be used for such studies.

Animals↗
PubMed1967

Effect of polyions on the infectivity of rabies virus in tissue culture: construction of a single-cycle growth curve.

The infectivity of fixed rabies virus in a number of cell lines has been shown to be markedly enhanced by the addition of protamine or diethylaminoethyl dextran to the virus inoculum. The polycations appear to exert their influence at a very early stage (adsorption or penetration or both) of virus-cell interaction. Immune globulin blocked infection completely when added up to 5 min after exposure and almost completely when added 5 to 15 min after infection. Antibody had no effect on adsorption and penetration when added to the inoculum 30 min or more after cells were exposed to the virus. Irradiation of BHK/21 cell monolayers with ultraviolet light increased their sensitivity to rabies virus. The events occurring after synchronous infection of cells in both irradiated and nonirradiated cell monolayers were followed by means of fluorescent-antibody staining and by intracerebral titration in mice. Virus-specific fluorescent antigen first appeared between 8 and 9 hr after infection, and in irradiated cultures there was a further lag period of 3 hr before infectious virus was produced intracellularly. Virus was first detected in the medium 12 to 15 hr after infection, and maximal yield of infectious virus was observed 48 hr after exposure. In nonirradiated cultures, formation of infectious virus was delayed, and the final yield of virus was also reduced.

Animals↗
PubMed1967

Structure and development of rabies virus in tissue culture.

Structure and development of two fixed rabies virus strains in baby hamster kidney cells (BHK/21) were investigated by electron microscopy. The morphological development was correlated with fluorescent-antibody staining and infectivity titration. The uptake of virus was enhanced by addition of diethylaminoethyl dextran, and structural changes became apparent in the cytoplasm 8 to 9 hr after infection, when fluorescent-antibody staining was first discernible. These changes consisted of matrices containing fibers replacing normal cytoplasmic structures. Virus particles appeared at the edges of these matrices and inside them at 24 to 48 hr. This corresponded to significant rises in intracellular infectious virus. Formation of virus particles by budding from cell membranes was seen at 72 hr. Further incubation of the infected cells resulted in synthesis of bizarre structural elements. The complete virus particle was bullet-shaped with an average size of 180 by 75 mmu. It consisted of an inner core of filamentous material surrounded by two membranes of different densities. The surface showed a honeycomb arrangement with surface protrusions 60 to 70 A long having a knoblike structure at their distal end. These surface protrusions were absent at the flat end of the virus particle.

Animals↗
PubMed1966

Density gradient centrifugation studies on rabies virus.

Neurath, A. Robert (The Wistar Institute, Philadelphia, Pa.), Tadeusz J. Wiktor, and Hilary Koprowski. Density gradient centrifugation studies on rabies virus. J. Bacteriol. 92:102-106. 1966.-Cesium chloride density gradient centrifugation of rabies virus revealed a heterogeneous population of infectious virus particles, the majority of which showed a density of 1.20 g/ml. From results obtained by rate zonal centrifugation in preformed sucrose gradients, it was possible to calculate a sedimentation coefficient of about 600S for rabies virus. Sedimentation coefficients of about 23S and 10S were calculated for two soluble rabies antigens present in infected tissue-culture fluids, and they showed a density of 1.26 g/ml in cesium chloride solutions.

Antigens↗
PubMedDate not supplied

Antigenic diversity of the glycoprotein and nucleocapsid proteins of rabies and rabies-related viruses: implications for epidemiology and control of rabies.

Rabies virus-specific monoclonal antibodies (MAbs) have served to describe operationally the topography of the antigenic structure of the glycoprotein and nucleocapsid proteins of rabies virus. With the use of nucleocapsid protein-specific MAbs and cleavage fragments of the nucleoprotein and phosphoprotein, it has been possible to identify the chemical structure of two antigenic sites of the nucleoprotein and one antigenic site of the phosphoprotein. Antisera produced to synthetic peptides that make up the structure of these antigenic sites exhibited reactivities similar to those of MAbs. Analysis of a large number of isolates of rabies virus from different animal species and from different geographic locations revealed that rabies viruses differ considerably in their antigenic structure and can be identified according to their characteristic reactivity patterns with MAbs. Analysis of field virus isolates has also revealed that strains of rabies virus generally are associated with only one or a few major mammalian hosts within any given geographic area. Protection experiments in mice have not demonstrated correlations between protective activity and degree of antigenic difference between the vaccine strain and the challenge virus. Therefore, changes in antigenic structure, as determined by analysis with rabies virus-specific MAbs, cannot predict whether a given rabies vaccine will protect against a particular field virus.

Animals↗
PubMedDate not supplied

Production and control of rabies vaccines made on diploid cells.

Introductory remarks on the advantages of antirabies vaccines obtained from human diploid cell cultures in comparison with brain tissue vaccine and duck embryo vaccine. The characteristics of these new types of vaccine are: (i) high antigenicity, (ii) rapid development of antibodies, (iii) absence of adverse reactions even when the booster inoculation was given two years later. The disadvantage is the high cost of production to obtain a highly purified product.

Antigens, Viral↗
PubMedDate not supplied

Post-exposure use of human diploid cell culture rabies vaccine.

880 individuals, 120 of which were exposed to rabid animals, were immunized pre- or post-exposure with 2 different BPL-inactivated and concentrated rabies vaccines prepared in HDC strains WI-38 and MRC-5. The vaccines were well tolerated and no major side effects were observed after primary immunization with 3-10 doses or 1 booster vaccination. The dynamics of neutralizing, antibody formation and persistence of antibodies in 4 different groups of vaccinees are described. The groups were vaccinated pre-exposure (I) on days 0, 28 and 56; (II) on days 0, 7 and 14; (III) on days 0, 3, 7 and 21; and (IV) post-exposure on days 0, 3, 7, 14, 30 and 90. High antibody levels--persisting for at least 30 months--were obtained in all patients. The CFT, using a concentrated and purified virion antigen, was highly specific for rabies virus antibody demonstration. Since in some 50 patients under severe risk, after having been bitten and/or scratched by proven rabid animals, not a single breakthough of immunity was observed during an observation time between 1/2 and 3 years, the protective effect of the HDCS-rabies vaccines seems to be excellent. With regard to their high immunogenicity and extremely low reactogenicity, the new HDCS-vaccines can be recommended for prophylactic and post-exposure immunization of man without any reserve. Data on simultaneous application of homologous anti-rabies gammaglobulin from man (20 I.E./kg body-weight) and HDCS-vaccines are also presented and discussed.

Adolescent↗
PubMedDate not supplied

[Characteristics of defective rabies virus particles formed in chronically infected cultures].

Cultural fluids of BHK-21/13S and HEp-2 cells chronically infected with rabies virus were used to determine the structures sedimenting in the sucrose gradient of the slow infectious virus. These structures have a polypeptide composition similar to that of rabies virus and contain subgenome RNA. Morphologically they are spherical virions. After amplification in BHK-21/13S cells the structures protected mice from lethal doses of rabies virus. The results obtained allow designation of the structures as defective interfering particles of rabies virus. The evidence is given on their participation in the establishment and maintaining of the chronic infection.

Cell Line↗