The retroviral replication process is typically separated into early events of infection for the virus to enter a host cell, and late events that generate new viral particles. Encapsidation (late event) and early infection events are governed by several different cis elements located in the viral RNA, and viral, or cellular, trans factors (proteins). A number of viral encoded components have been identified to function in the encapsidation process, most notably the Gag polyprotein and genomic RNA cis elements in the 5' untranslated region (UTR). Although conventionally associated with nuclear export of HIV-1 RNA, there is also a burgeoning role for the Rev/RRE in the encapsidation process. Additionally, cis elements of the RNAs encapsidated into viral particles may influence different early stages of infection into host cells. This dissertation employs an innovative approach that affords separation of cis and trans viral components to investigate their independent, and combined, effects on encapsidation and early events of infection that will be referred to as transduction. HIV-1 cis elements were reconstructed in the context of heterologous RNAs to assess encapsidation and transduction functions.
This work demonstrates for the first time that the Rev/RRE system can augment heterologous RNA encapsidation independent of all cis elements from the 5' UTR. In fact, the Rev/RRE system appears to be required for specific and efficient encapsidation into HIV-1 viral particles, a process more commonly associated with Gag recognition of the canonical packaging signal in the 5' UTR. Premised on encapsidation of a heterologous RNA into HIV-1 viral particles, our findings define a functional HIV-1 packaging system as comprising the 5' UTR cis elements, Gag, and the Rev/RRE system, in which the Rev/RRE system is required to make the RNA amenable to ensuing interactions between Gag and the canonical packaging signal for subsequent encapsidation. Lastly, we show that heterologous RNAs can conform to transduction properties commonly associated with HIV-1 viral particles. Furthermore, some heterologous RNAs exhibit an episomal profile in transduced cells that may have improved safety benefits over more conventional nonintegrating lentiviral vectors. These innovative vector systems may prove beneficial for therapeutic gene delivery to nondividing cells.
|Commitee:||Heise, Mark, Hope, Thomas, Samulski, Richard J., Su, Lishan, Swanstrom, Ronald|
|School:||The University of North Carolina at Chapel Hill|
|Department:||Genetics & Molecular Biology|
|School Location:||United States -- North Carolina|
|Source:||DAI-B 73/06, Dissertation Abstracts International|
|Keywords:||Cis elements, Hiv, Packaging, RNA encapsidation, RNA transduction, Rev|
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