Laurent Berthiaume

Guidelines for Bacteriophage Characterization

Publisher Summary Bacteriophages or phages occur in a wide range of prokaryotes, including bacteria and blue-green algae. With an estimated 1650 isolates studied by electron microscopy, they are the largest viral group described. This group is expanding at a rate of about 130 to 150 virus descriptions per year. These large numbers reflect the relative ease, with which the phages are isolated and their enormous importance for molecular biology, genetics, and epidemiology. For example, a recent review lists typing sets for about 70 bacterial species and serotypes. Although most work has been done on the phages of bacteria pathogenic to humans, there is presently a trend toward studying the phages of nonmedical and sometimes arcane bacteria. The isolation of the new phages raises problems for the investigators, the journal editors, and the scientific public alike. At present, there is no agreement on parameters, methods, and nomenclature. This has led to widely different, often unsatisfactory, phage descriptions and many identical names for different phages. In addition, much effort seems to be devoted to the study of obsolete parameters or properties that, for the lack of standard methods, cannot be compared with existing data. Such a situation is detrimental to comparative virology. The purpose of this chapter is to suggest the guidelines for phage characterization and nomenclature, and to set forth the minimum requirements for their description.

Evidence of a major neutralizable conformational epitope region on VP2 of infectious pancreatic necrosis virus.

A collection of neutralizing monoclonal antibodies (MAbs) produced against the LWVRT 60.1, Jasper and N1 strains of infectious pancreatic necrosis virus (IPNV) were selected for the analysis of VP2 epitopes. Previous characterization of the LW and JA MAbs allowed the identification of continuous and discontinuous epitopes but the topological localization of these sites remained obscure. The ability of these MAbs to differentiate individual epitopes was evaluated by additivity and competition assays using antigen-coated plates and by surface plasmon resonance (SPR), an automated biosensor system that is able to retain the conformation integrity of proteins. IPNV-neutralizing MAbs defined a major, conformational-dependent and immunodominant area where continuous epitopes represent portions of a larger discontinuous epitope. Moreover, weakly neutralizing MAbs could interact with internal sites, located within the foldings of the polypeptide chain. Anti-VP2 MAbs prepared against the European serotype N1 recognized and competed for epitopes present on the North American strain LWVRT 60.1 and Jasper. Attempts to establish the proximity of VP2 and VP3 epitopes have been made by SPR. Results indicate that these major structural proteins do not overlap in the virion.

New Actinophage Species

All actinophages of known morphology are tailed. From 305 phages surveyed, 4 belong to the Myoviridae family, 283 to the Siphoviridae, and 18 to the Podoviridae (two morphotypes each). 58 of 139 actinophages described since 1976 are classified in this report, and the earlier phage descriptions are updated. Nine new species and type viruses are proposed, bringing the total number of actinophage species to 29 and the number of bacterial host genera to 15.

Antigenic and Genomic Differences of Two Jasper Strains of Infectious Pancreatic Necrosis Virus

Strains of infectious pancreatic necrosis virus (IPNV-Jasper) obtained from two different laboratories were compared serologically with polyclonal and monoclonal antibodies. Nucleotide sequence and restriction endonuclease patterns of 359-bp fragment of genome segment A cDNA were also compared. Substantial differences were found in both analyses that will support the fact that the two Jasper strains are not identical.

Viral Pathogenesis in Diagrams

INTRODUCTION A SUMMARY OF VIRUS CLASSIFICATION VIRAL PATHOGENESIS IN VERTEBRATES: PRINCIPLES VERTEBRATE VIRUSES: INFECTION Types of disease Virus spread Cytopathology VERTEBRATE VIRUSES: HOST DEFENSE Organismic Defense Cellular Defense VERTEBRATE VIRUSES BY FAMILY Adenoviridae Arenaviridae Bunyaviridae Caliciviridae Coronaviridae Filoviridae Flaviviridae Hepadnaviridae Herpesvirida Orthomyxoviridae Papillomaviridae Paramyxoviridae Parvoviridae Picornaviridae Poxviridae Reoviridae Retroviridae Rhabdoviridae Togaviridae INSECT VIRUSES Baculoviridae Polydnaviridae PLANT VIRUSES Infection and Virus Spread Histo- and Cytopathology ABBREVIATIONS AND UNITS GLOSSARY REFERENCES INDEX