Purified DNA from a nalidixic acid resistant derivative of a virulent serotype 0:3 clinical isolate of Yersinia enterocolitica was subjected to transpositional mutagenesis in an effort to construct avirulent mutants. The resulting transpositional mutants, as well as the wild-type virulent strain and its isogenic derivative that had been cured of the virulence plasmid, were analyzed for plasmid DNA content. The plasmid DNA content of each strain was further characterized by restriction endonuclease digestion and the transposon insertion sites for the mutants were located. All of the strains were then tested for pathogenicity by the following assays: calcium dependence, colonization of the mouse gastrointestinal tract, HEp-2 cell adherence and invasion, HEp-2 cell monolayer detachment, autoagglutination, serum resistance, outer membrane protein production and production of V antigen. In addition, the hydrophobic properties of each strain were examined by a rapid polystyrene plate method and hydrophobic interaction chromatography. The results of the tests were compared to plasmid DNA analyses for each strain in an attempt to identify any plasmid-associated genes that are related to virulence. The wild-type strain was virulent, or positive, by all of the assays employed for evaluation of pathogenicity. In contrast, its isogenic derivative that had been cured of the virulence plasmid was negative, or avirulent, for the same assays with one exception. The avirulent plasmidless strain still retained the ability to adhere to and invade HEp-2 cells, supporting the belief that these properties are probably encoded by the bacterial chromosome. In addition, three transpositional mutants were constructed that were no longer calcium dependent, capable of detaching HEp-2 cell monolayers or able to produce three unique outer membrane proteins. Restriction endonuclease analysis confirmed the presence of the transposon on the Hind III "A" fragment of the virulence plasmid and located the region responsible for the lost virulence properties. The gene or set of genes identified were designated cal and the respective calcium independent mutants Cal⁻. Furthermore, the assays for hydrophobicity indicated that the virulence plasmid, specifically the cal gene(s), codes for hydrophobic properties on the surface of the bacterium. The study demonstrated that a virulence-associated region, cal, is located on the virulence plasmid of Y. entrocolitica and responsible for calcium dependence, HEp-2 cell monolayer detachment, the production of the three plasmid-specified outer membrane proteins and cell-surface hydrophobicity.

Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Biology. / Microfiche copy available in Archives and Science. / Bibliography : leaves 272-276. / Ph.D.

Includes Appendix listing other publications by the author. Includes bibliographical references (leaves 134-181). Alfalfa mosaic virus was isolated from lucerne (Medicago sativa) plants with a variety of disease symptoms. Experiments showed that each isolate was biologically distinct and that the host range and symptomatology of each isolate was affected by the environmental condition.

Includes appendix containing journal publications co-authored by the author. Includes bibliographical references (leaves 130-151). Eighteen strains of Cucumber mosaic virus, including forteen from Australia, two from the USA, and two from Japan were used in this study.

Includes bibliographical references (leaves 82-92). Five isolates of pea seed-borne mosaic virus were compared by host range and symptomatology on 16 pisum sativum cultivars lines, 21 lines of Lathyrus and Lens spp. and several indicator species

Includes bibliographical references (leaves [102]-120). Studies the structure of the cucumber mosaic virus genome and the control of its expression.

Includes appendix containing journal publications co-authored by the author. / Includes bibliographical references (leaves 130-151). / xiii, 151 leaves : ill., photos ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Eighteen strains of Cucumber mosaic virus, including forteen from Australia, two from the USA, and two from Japan were used in this study. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1992

Includes bibliographical references (leaves 82-92). / xii, 92 leaves : ill., photos ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Five isolates of pea seed-borne mosaic virus were compared by host range and symptomatology on 16 pisum sativum cultivars lines, 21 lines of Lathyrus and Lens spp. and several indicator species / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1993

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Includes bibliographical references (leaves 108-123). Includes the paper: Stabilization of capsid structure and enhancement of immunogenicity of cucumber mosaic virus (Q strain) by formaldehyde / by R.I.B. Franki and N. Habili, originally published in Virology, v. 48, no. 2, 1972 The comparative studies carried out suggest that tomato aspermy virus and the Q strain of cucumber mosaic virus are sufficiently similar to be included in the same taxonomic group. Nevertheless, the two viruses are distinct and the present nomenclature should be retained.