Host factors involved in viral movement through plants

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Title: Host factors involved in viral movement through plants
Author: Seaberg, Bonnie Lee
Abstract: Tomato bushy stunt virus (TBSV ) is a positive -sense single -stranded RNA virus . It encodes five open reading frames (ORFs ) , including two nested genes , expressing movement -associated proteins . One of these proteins , P22 , interacts with a host transcription factor containing a homeodomain leucine -zipper motif , known as HFi22 . Similar proteins of this type traffic their RNA from cell -to -cell , suggesting the possiblity that HFi22 is involved in the cell -to -cell movement of TBSV RNA . To further characterize the nature of the interaction between P22 and HFi22 on the cellular level , cellular fractionation experiments were conducted . To investigate the functional role of HFi22 in viral movement I attempted to inactivate its expression using a virus induced gene silencing system with a Tobacco rattle virus (TRV ) vector . A final objective was based on the notion that different hosts can impact the stability of viruses used to express foreign genes of biotechnological interest . To compare virus stability in different hosts , TBSV expressing the green fluorescent protein (GFP ) was inoculated onto various TBSV hosts , and infected leaf tissue was then used as inoculum to be rubbed onto a local lesion host . This technique made it possible to quantify the number of fluorescent foci versus total lesions . Results obtained for the first objective indicate that P22 and HFi22 co -fractionate in nucleus and membrane -enriched samples . In addition , it was found that HFi22 is largely conserved through a wide variety of plant species but not in lettuce , which was found to be compromised for effective virus spread . Control experiments for the second objective showed that plants were successfully silenced with TRV carrying the phytoene desaturase (PDS ) gene resulting in photobleaching , however attempts to silence HFi22 have not yielded conclusive results . The results obtained for the third objective indicate there is a difference in how efficiently a foreign gene insert is maintained by TBSV in different host plants . In summary , the overall results of this research showed that host factors influence the host -virus interaction but their exact contributions remain elusive .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3282
Date: 2009-05-15

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Host factors involved in viral movement through plants. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3282 .

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