Can mycoviruses be used as biological control agents against Aspergillus?

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dc.contributor.advisor Pearson, MN en
dc.contributor.advisor Holland, D en
dc.contributor.author Ejmal, Mahjoub en
dc.date.accessioned 2017-03-28T23:29:26Z en
dc.date.issued 2017 en
dc.identifier.uri http://hdl.handle.net/2292/32352 en
dc.description.abstract Mycoviruses are becoming increasingly recognised for their potential as biocontrol agents against phytopathogenic fungi which has raised the question to what extent mycoviruses could be effective and applicable to the control of Aspergillus, possibly including human infections. A total of 50 clinical and environmental Aspergillus isolates were screened for the presence of dsRNAs, indicative of mycovirus infection. Eight isolates contained dsRNAs, six of which also contained isometric virus-like particles. Of particular interest was an isolate of Aspergillus thermomutatus which exhibited very low asexual sporulation. Sequencing of the dsRNAs identified the virus as a chrysovirus, tentatively named Aspergillus thermomutatus chrysovirus 1 (AthCV1), the genome of which consists of four segments encoding; a putative RNA-dependent RNA polymerase (3589 nt, 1114 aa), a CP (2772 nt, 825 aa), and two HPs (2676 nt, 768 aa and 2514 nt, 711 aa). A genetically identical virus free A. thermomutatus line, cured by cycloheximide treatment, produced large numbers of conidia but no ascospores at both 20⁰C and 37⁰C, whereas the virus infected line produced large numbers of ascospores at both temperatures and ten-fold fewer conidia at 20⁰C. To study possible effects of AthCV1 on other Aspergillus species, virus free isolates of A. fumigatus, A. nidulans and A. niger were transfected with AthCV1 particles and their phenotypic reaction assessed. Both virus free and virus infected A. fumigatus produced only conidia at both temperatures, but with at least a ten-fold reduction in sporulation in the virus infected line. Conidial production was also significantly reduced in the infected lines of A. nidulans and A. niger at 37⁰C. Transcriptome profiling of virus free and virus infected isolates of all four Aspergillus species at 37⁰C showed changes in the expression of a variety of genes with a wide range of functions, including several genes with known roles in sexual and/or asexual sporulation. The successful virus transfection to different Aspergillus species accompanied by the substantial decrease in A. fumigatus sporulation at both 37⁰C and 20⁰C provides a starting point for evaluating the potential of mycoviruses as an alternative control method to treat Aspergillus infection. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA99264910712702091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title Can mycoviruses be used as biological control agents against Aspergillus? en
dc.type Thesis en
thesis.degree.discipline Biological Sciences en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Doctoral en
thesis.degree.name PhD en
dc.rights.holder Copyright: The author en
dc.rights.accessrights http://purl.org/eprint/accessRights/OpenAccess en
pubs.elements-id 618982 en
pubs.record-created-at-source-date 2017-03-29 en


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