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

Corrigendum inserted at the back. Includes bibliographical references (leaves 133-158). Ch. 1. General introduction -- ch. 2. General materials and methods -- ch. 3. Biological characterisation of Australian PSbMV isolates -- ch. 4. Developing nucleic acid based diagnostics for PSbMV -- ch. 5. Detection of PSbMV isolates by RT-PCR and RFLP analysis -- ch. 6. Developing an internal control for PSbMV RT-PCR -- ch. 7. Molecular analysis of the PSbMV VPG -- ch. 8. PSbMV sequence and phylogenetic analysis -- ch. 9. General discussion Sixteen pea seed borne mosaic virus (PSbMV) isolates were collected between 1995 and 1998. These isolates were biologically distinct yet serologically indistinguishable. The conclusion is that PSbMV is widespread and occurs at a low incidence in Australia. Reports sequence information on new isolates of PSbMV which has allowed genomic regions to be identified which distinguish PSbMV pathotypes and isolates; and, to the development of PSbMV nucleic acid hybridisation and RT-PCR assays.

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

Corrigendum inserted at the back. / Includes bibliographical references (leaves 133-158). / xvi, 158 leaves : ill., col. map ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Sixteen pea seed borne mosaic virus (PSbMV) isolates were collected between 1995 and 1998. These isolates were biologically distinct yet serologically indistinguishable. The conclusion is that PSbMV is widespread and occurs at a low incidence in Australia. Reports sequence information on new isolates of PSbMV which has allowed genomic regions to be identified which distinguish PSbMV pathotypes and isolates; and, to the development of PSbMV nucleic acid hybridisation and RT-PCR assays. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 2001

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.

Typescript (photocopy) Includes bibliographical references (leaves 84-94). Eight cucumovirus isolates were examined with respect to their host range, antigenic properties and nucleic acid composition.

Beet yellows virus (BYV) is a filamentous, positive-strand RNA virus that belongs to the family Closteroviridae. BYV particles encapsidate a 15.5 kb RNA and posses complex polar architecture. A long virion body is formed by the major capsid protein(CP), whereas the minor capsid protein (CPm) assembles a short tail that encapsidates the 5'-terminal region of BYV RNA. In addition to proteins required for viral RNA replication and encapsidation, BYV encodes four proteins whose role in the virus life cycle was unknown. These proteins include a small, 6-kDa, hydrophobic protein (p6), a homolog of the cellular 70-kDa heat shock proteins (Hsp7Oh), a 64-kDa protein (p64), and a 20-kDa protein (p20). It was found recently that Hsp7Oh, p64, and p20 are incorporated into BYV virions, and that Hsp7Oh is required for the virus movement from cell to cell. In this study, we characterized genetic requirements for BYV assembly and cell-to-cell movement, and determined relationships between these two processes. It was demonstrated that in addition to Hsp7Oh, p6, p64, CP, and CPm are each essential, but not sufficient for virus movement. These results indicated that five-component movement machinery of BYV is the most complex among plant viruses. Extensive mutational analysis of CP and CPm revealed strong correlation between abilities of BYV to assemble tailed virions and to move from cell to cell, suggesting that formation of functional virions is a prerequisite for virus translocation. We have found that CPm, Hsp7Oh, and p64 are necessary for the efficient virion tail formation. Assembly of the virion tails and bodies was shown to occur independent of each other and likely to involve two separate packaging signals within the genomic RNA. Our work demonstrated that BYV encodes one conventional movement protein, p6, whose only known function is to mediate virus movement. The other four movement associated proteins of BYV, CP, CPm, Hsp7Oh, and p64 are the virion components, each of which is required for assembly of the tailed, movement-competent virions. Based on these and other data, we propose that BYV and other closteroviruses evolved virion tails as a specialized device for the directional cell-to-cell movement of large RNA genomes. / Graduation date: 2005 / Best scan available.

More than half of the recognized genera of positive strand RNA viruses employ polyprotein processing as one of the strategies for their genome expression. Normally, this processing is mediated by virus-encoded proteinases that belong to the trypsin-like or papain-like family. In particular, papain-like, leader proteinases were found in diverse families of human, animal, plant, and fungal positive strand RNA viruses. In addition to autocatalytic processing, these proteinases play a variety of roles in the virus life cycle. In plant potyviruses, a papain-like helper component-proteinase (HC-Pro) was implicated in genome amplification, cell-to-cell movement, long distance transport, and suppression of host defense. The p29 proteinase encoded by a fungal hypovirus CHV1 was found to be dispensable for virus replication, but it was identified as a major determinant of viral pathogenicity. In an animal equine aterivirus (EAV), a papain-like proteinase nspl was demonstrated to possess a putative zinc finger domain, which functions in subgenomic RNA synthesis, although it is not essential for virus replication. The Lab proteinase of the foot and mouse disease virus (FMDV) is involved in inhibition of cellular mRNA translation and in virus spread in infected animals. In general, it appears that functional plasticity of the papain-like leader proteinases played an important role in the evolution of viral diversity. Here, we examined the functions of a papain-like leader proteinase (L-Pro) in the life cycle of the beet yellows closterovirus (BYV). It was found that L-Pro is required for autoproteolytic processing, genome amplification, virus invasiveness and cell-to-cell movement for BYV. The gene swapping experiments involving several closterviruses, a potyvirus, as well as CHV1, FMDV, and EAV revealed complex functional profiles of the papain-like leader proteinases. The possible mechanisms that underlie L-Pro functions are discussed. / Graduation date: 2002