Studies into the role of capsid serine/threonine residues in HIV core stability and virus replication.

Disassembly of the HIV viral core describes the rearrangement and release of capsid (CA) from the core following entry into the host cell. In this process, while the conical shaped core may be lost, some CA remains associated with the resulting reverse transcription (RTC) and preintegration complexes (PIC). What triggers release of CA from the core is unknown. Cores from virus containing mutations in CA that show altered core stability, and release CA from the core at rates faster or slower than wild type (WT) virus demonstrate blocks in replication during reverse transcription and nuclear translocation. How the CA protein affects theses process is not understood, but intrinsic stability of the core is instrumental in regulating interactions with cellular factors. Evidence suggests that core disassembly is critical for the early steps in HIV replication and it may regulate replication in a cell type dependent fashion. Mutation of charged residues throughout CA results in viruses displaying altered core stability. Regulation of charge in the core, possibly by phosphorylation of CA, is one potential mechanism that may control core disassembly. Substitution of serine residues within CA illustrates five viruses, including three representing the major phospho-acceptor sites (S109, S149 and S178) that show altered replication profiles. To explore the role of these residues in core disassembly, the present study investigated the in vitro stability and the intracellular disassembly of the cores from these viruses. Chapter 3 describes the characterisation of viruses with mutations in CA at S41A, S109A, S146A, S149A, S178A and T188V to analyse the effect of substitution at these sites on viral replication. Substitution at S109, S149, S178 and T188 reduced replication competence and altered the production of reverse transcription intermediates. S41A and S146A demonstrated altered reverse transcription, but did not result in blocks in replication. Chapter 4 describes modification of an assay to examine viral core stability. Using this assay, CA mutant viruses (S109A, S149A and S178A) demonstrated reduced in vitro stability of the viral core in comparison with WT NL4-3 virus. Analysis of core disassembly following cell infection (Chapter 5) could not identify defects in core disassembly inside the cell, but suggested progressive changes occurred to viral complexes following infection. The results in this thesis suggest that substitution in CA at S109, S149 and S178 alters in vitro core stability in these viruses, and may impact on core disassembly during HIV replication.

Author dc:creator

• Martin, Sarah Mary-Rose Connor

Advisors dc:contributor.advisor

• Peng, Li
• Burrell, Christopher John
• Davis, Adam James

• HIV; capsid; core stability

Handle dc:identifier.uri

http://hdl.handle.net/2440/84126

OAI identifier oai:identifier

oai:digital.library.adelaide.edu.au:2440/84126