The role of proteolytic processing in the morphogenesis of virus particles

Proteinases are encoded by many RNA viruses, all retroviruses and several DNA viruses. They play essential roles at various stages in viral replication, including the coordinated assembly and maturation of virions. Most of these enzymes belong to one of three (Ser, Cys or Asp) of the four major classes of proteinases, and have highly substrate-selective and cleavage specific activities. They can be thought of as playing one of two general roles in viral morphogenesis. Structural proteins are encoded by retroviruses and many RNA viruses as part of large polyproteins. Their proteolytic release is a prerequisite to particle assembly; consequent structural rearrangement of the capsid domains serves to regulate and direct association and assembly of capsid subunits. The second general role of proteolysis is in assembly-dependent maturation of virus particles, which is accompanied by the acquisition of infectivity.     

Demonstration of virus particles in ovine pulmonary adenomata

Zusammenfassung Elektronenmikroskopischer Nachweis bei Lungen-Adenokarzinomen von Schafen, dass diese jeweils zusammen mit Viruspartikeln auftreten, die morphologisch solchen aus verschiedenen spontanen und übertragbaren Neoplasmen von Geflügel, Nagetieren und Katzen ähnlich sind.     

Molecular mimicry and the role of B lymphocytes in the processing of autoantigens

The immune system has evolved several mechanisms that provide lymphocytes with the intelligence to ignore self proteins while attacking foreign pathogenic agents. Notably, B and T lymphocytes that encounter self antigen at either the inappropriate levels or affinity are usually instructed to perish or become anergized. However, the presence of autoimmune disease suggests that the induction of self tolerance is not foolproof. In fact, autoreactive cells are now found to be normal inhabitants of the B and T lymphocyte repertoire. This review examines how foreign peptides which resemble self proteins can elicit autoimmunity that is amplified to many sites on a target autoantigen. In particular, B lymphocytes initiated by foreign molecular mimics can process and present self peptides in the shaping of autoimmune T cell responses.     

Sampling of virus particles and macromolecules sedimented in an equilibrium density gradient

Résumé La distribution de composés macromoléculaires, stratifiés dans un gradient de densité de CsCl établi par une ultracentrifugation prolongée, est déterminée quantitativement par le recoupage du contenu du tube. Une courte aiguille hypodermique est tout simplement insérée dans le fond du tube. Le contenu du tube s'épanche goutte à goutte. Les fractions de recoupage peuvent être ensuite analysées une à une.

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This research was supported in part by the National Science Foundation.     

The roles of collagen genes in skeletal development and morphogenesis

Molecular genetic analyses of osteochondrodysplasias in mice and humans have recently led to the identification of mutations in genes encoding structural proteins growth factor receptors and sulphate transporters. Further analyses of such inherited disorders, using rapid techniques for gene mapping, positional cloning and mutation detection, will undoubtedly uncover other genes that are important for skeletal development. Together with studies of transgenic mice, in which specific genes that are expressed in the skeleton are mutated, these analyses will provide insight into genes that are essential for skeletal morphogenesis.     

The influence of proteolytic enzymes inhibitor on the course of lymphocyte transformation in vitro

Résumé Nous avons observé que l'inhibiteur d'enzymes protéolytiques (Zymofren-Specia) inhibe la transformation blastique des lymphocytes sensibilisés de cobaye évoquee par la phytohémagglutinine ou l'antigène. Nous n'avons pas observé d'influence ce de produit sur la consommation d'oxygène.     

Changes effected in vitro upon some morphological properties of particles of virus BAI-strain A

Zusammenfassung Sphäroidale und phag-ähnliche Form des Hühner-Leukosis-Virus (BAI, Stamm A) wird der Existenz eines kontrahierbaren Systems (Interaktion mit ATP) zugeschrieben. Formveränderungen des Viruspartikels unter ATP-Einfluss werden in vitro dargestellt, wobei Parachlormorcuribenzoat, Phenylmercuriborat und N-Äthylmaleimid als Inhibitoren wirken.     

C-type virus particles in lymphocytes cultured from cows with persistant lymphocytosis. Preliminary results on French cattle stock]

C type virus particles were shown in cultures of lymphocytes originating from cows with persistent lymphocytosis. These observations on French cattle are in complete accordance with data previously obtained in the USA. Viral replication is highly stimulated by the addition of phytohemagglutinin in the culture medium. Several morphological and biological properties, specific to the bovine virus differentiate this virus from C type viruses of other species.