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Summary Replication of pseudorabies virus (PrV) in Chinese hamster ovary (CHO) cells, a cell line naturally resistant to infection by herpesviruses, is blocked at the level of penetration. Virions bound to the surface of CHO cells are taken up into cytoplasmic vesicles and degraded.

Summary Neutralization of poliovirus type 1 was studied using radioactively labelled polyclonal IgG. With nonsaturating antibody concentrations various virus-antibody complexes were produced which were isolated by sucrose gradient centrifugation and identified by electron microscopy as virus monomers, dimers, trimers, tetramers and pentamers. The neutralization rate (n. r.) of each of the virus-antibody complexes relative to non-neutralized virus and the stoichiometry have been estimated. The monomer fraction showed that about every fifth virion was associated with one IgG molecule and neutralized. The antibody was bivalently attached. The majority of virus particles formed aggregates of different sizes, which were cross-linked by antibodies. The following neutralization rates and ratios of IgG to virus (IgG/V) were determined for the oligomers: dimers, 59.2 per cent n. r. and 0.55 IgG/V; trimers, 67.3 per cent n. r. and 0.66 IgG/V; tetramers, 79.0 per cent n. r. and 0.75 IgG/V; pentamers, 86.3 per cent n. r. and 0.98 IgG/V.

Summary The aim of the study was to evaluate a new ELISA for detection of HIV-1, HIV-2 and HIV-1 subtype 0 (HIV-0) antibodies. The assay format is based on the antigen sandwich principle. To enable specific detection of HIV-0 antibodies, in addition to HIV-1 and HIV-2 antigens HIV-0 antigen is used for coating the solid phase and for the conjugate. The results show that all 12 HIV-0 samples tested were detected with a high degree of reactivity, as were all the 1,144 anti-HIV-1 and 424 anti-HIV-2 positive samples. The capacity of the test to enable early detection of seroconversions is equivalent to that of other sandwich ELISAs. The specificity of the assay was determined to be 99.89/99.94% (initial/after retest) using 58,366 samples, which is superior to the other ELISAs used for comparison. Even with difficult samples (i.e. samples of African origin, samples known to cause false-positive reactivity in different ELISAs, or samples containing potential interference factors) there were very few false-positive reactions. Therefore, the new assay is well suited for screening blood donations as well as for evaluating samples from patients of different geographic origin.

The two types of herpes simplex virus (HSV-1, HSV-2) induced significantly different alterations in the morphology and permeability of infected cells. HEp-2 cells infected with HSV-1 (strain THEA) were characterized by the formation of polynuclear syncytia. In contrast, after infection with HSV-2 (strain D316, DD), the cells were rounded up. The HSV-1 strains KOS and LS5039 and the HSV-2 strain 196 induced both types of cytopathic effect. As shown by comparative scanning and transmission electron microscopy newly synthesized virus particles of the various strains of HSV-1 were generally found to be restricted to smooth areas of the cell surface. In these areas the number of microvilli was reduced in comparison to uninfected cells. However, the progeny viruses of the strains of HSV-2 were mainly connected with protrusions of the cell membrane (microvilli and filopodia).

The glycoprotein complex gII of pseudorabies virus was isolated by immunoprecipitation with the monoclonal antibody M5, which was covalently linked to protein A-Sepharose. After sodium dodecyl sulfate-polyarylamide gel electrophoresis under reducing conditions and blotting onto poly(vinylidene difluoride) membrane, its subunits, gIIa, gIIb, and gIIc, were subjected to N-terminal sequencing. gIIa and gIIb start at position 59 and gIIc starts at position 503 according to the amino acid sequence deduced from the gene, indicating that there is one major protein (gIIa) which is cleaved into the two protein fragments gIIb and gIIc. Protein labeling with 14C-amino acids gave no indication that the three proteins (gIIa, gIIb, and gIIc) of the complex are present in equimolar ratios. It seems that gIIa is only a minor component of the complex, whereas gIIb and gIIc are contained in equimolar amounts.

Previously we have reported that among the proteins of purified pseudorabies virions there are four major glycoproteins (T. Ben-Porat and A. S. Kaplan, Virology 41:265-273, 1970). Several minor glycoproteins can also be identified by two-dimensional gel electrophoresis. Removal of the viral envelope with Triton X-100 selectively removes from the virions all of the glycoproteins as well as several non-glycosylated proteins. Sedimentation analysis or chromatography of these proteins reveals that several are complexed with one another, some being covalently linked via disulfide bridges. Analysis of the proteins by immunoprecipitation with monoclonal antibodies reactive with the membrane proteins showed also that three of the four major virus glycoproteins (125K, 74K, and 58K; gIIa, gIIb, and gIIc, respectively) are linked covalently by disulfide bridges. Furthermore, all three share extensive sequence homology as indicated by the identity of their antigenic determinants and by partial peptide mapping; they probably originate from a single protein precursor. The fourth major glycoprotein (98K; gIII) is not complexed to any other protein. Three minor glycoproteins (130K [gI], 98K [gIV], and 62K [gV]), which form a noncovalently linked complex with a 115K nonglycosylated protein, have also been identified. Of the monoclonal antibodies used in this study, only those reactive with the major 98K glycoprotein (gIII) inhibit virus adsorption and neutralize virus infectivity in the absence of complement. However, all react with surface components of the virion, indicating that the proteins with which they react are exposed on the surface of the virions. A nomenclature for the pseudorabies virus glycoproteins is proposed.

HEp-2 cells, which were infected with HSV-1, excrete besides other proteins a soluble glycoprotein (Mr 125000–130000) related to the virus protein gC. The excretion of the glycoprotein and the production of extracellular virus particles is reduced to a similar extent when the cells were treated with monensin. Possible consequences of the excretion of soluble viral proteins to a modulation of the immune response are discussed.

Zusammenfassung Die im Beginn des Poliovirus-Reproduktionszyklus ablaufenden Vorgänge bewirken eine Mitosestimulierung in den ersten Stunden nach Infektionsbeginn. Wird der Infektionsablauf durch. Guanidin gehemmt, so kommt es nach 7 bis 14 Stunden zur Blockierung des Mitoseablaufes in der Metaphase unter dem Bilde eines Colchizin-ähnlichen Effektes. Weiterhin erlischt zu diesem Zeitpunkt die Mitoseaktivität. — Der Colchizin-ähnliche Effekt ist durch eine gestörte Anordnung der Chromosomen in der Äquatorialebene der Metaphaseplatte gekennzeichnet und entspricht dem Bilde der C-Mitose.

Summary Complete poliovirus reproduction-cycle in human aneuploid tissue culture cells causes chromosomal damage and increase of non-particulate lysosomal enzymes. — Guanidine-inhibition of late stages of infection gives evidence that breakage and c-anaphase-like chromosomes are independent of the complete reproduction-cycle. Severe diffuse chromoomal alterations, however, and increase of lysosomal enzymes require late stages of infection. — In this host-virus-system lysosomal enzymes are not responsible for incidence of chromosomal breakage and c-anaphaselike figures. The role of lysosomal enzymes for severe diffuse chromosomal alterations is still in question.

Zusammenfassung 1.An Monolayerkulturen von embryonalen MÄusefibroblasten wurde die Adsorption und der Eintritt in die Eklipse von Ektromelievirus untersucht.2.Die Bestimmung der Dynamik der Virusadsorption ergab eine gute übereinstimmung mit der durch die Poissonsche Gleichung gegebenen Wahrscheinlichkeit.3.Die Menge des an die Zellen in infektiöser Form gebundenen Virus nahm im Verlaufe des Adsorptionsvorganges zu, war jedoch wÄhrend der Initialphase der Infektion von untergeordneter Bedeutung. ElutionsvorgÄnge konnten beobachtet werden.4.Bereits 30 Minuten nach der Infektion war der grö\te Teil des Virus in die Eklipsephase eingetreten. Die Relation der Menge des in die Eklipse eingetretenen Virus zur Inokulationsdosis war über weite Dosisbereiche hin konstant.5.Die Thermoinaktivierung hatte keinen wesentlichen Einflu\ auf den Ablauf der initialen Phase der Infektion.

Es wird eine latente Infektion von Mäuseembryonen infolge diaplacentarer Virusübertragung beschrieben, die im Verlaufe einer Ektromelie-Endemie entstanden ist.

Es wird eine Photokammer für kinematographische Untersuchungen von Gewebekulturen beschrieben, die ohne Nährmediumwechsel eine mehrtägige Beobachtung gestattet.Die Fusion von embryonalen Mäusefibroblasten zu Riesenzellen nach Infektion mit Ektromelievirus wird beschrieben.Unter dem Einfluß von Ektromelievirus kommt es in den Riesenzellen zur Bildung von Einschlußkörpern, die kontinuierlich an Größe zunehmen und bisweilen miteinander verschmelzen.Die in den Randgebieten der Zellen liegenden Elementarkörper und deren Freisetzung durch verschiedenartige cytoplasmatische Protrusionen der Zellen werden dargestellt.

Zusammenfassung Es wird eine Methode zur Darstellung isolierter Leberzellen beschrieben. Diese Zellen weisen eine große Empfindlichkeit gegenüber Trypsin, eine geringere gegenüber mechanischer Belastung oder Ultraschall auf. Isolierte Leberzellen embryonaler Mäuse lassen sich in der Gewebekultur anzüchten.

Zusammenfassung 1. Streptomycingaben verschiedener Dosen während eines Zeitraumes von 1 oder 3 Monaten hatten keinen unterschiedlichen Effekt.

A variant of Theiler Encephalomyelitis Virus (TEM) was obtained by adaptation to embryo mouse fibroblasts. After the 22ndpassage three serial plaquepurifications were performed and the amount of the virus increased by a further passage. The variant is characterized by a remarkable decrease in pathogenicity, by a change in the symptoms of the disease and by a prolongation of the period of latency. The identity of the adapted virus strain with the original one could be proved by neutralization tests. Further propagation of the adapted virus under the conditions of the original environment by serial brain passages showed, that the new properties developed in tissue culture remained constant. This as well as the cytopathogenic effect, suddenly arising after 9 blind passages, indicated the existence of a genotypic adaptation.