Vaccinia virus assembly and motility

Vaccinia virus, the prototype member of the orthopoxviruses, is the largest and the most complex virus known. After replication of its genome and expression of the viral proteins, vaccinia undergoes a complicated assembly process which produces two distinct infectious forms. The first of these, the intracellular mature virus (IMV), develops from the immature virion (IV) after packaging of the genome and cleavage of the core proteins. During the transition of the IV to the IMV, a new core structure develops in the centre of the virion, concomitantly with the appearance of spike-like structures which extend between this core and the surrounding membranes of the IMV. I describe the characterization of p39 (gene A4L) which is hypothesized to be one component of these spikes. p39 is a core protein, but has strong associations with the membranes surrounding the IMV, possibly due to an interaction with p21 (A17L). Due to its location between the core and the membranes of the IMV, p39 is ideally situated to act as a matrix-like linker protein and may play a role in the formation of the core during the transition of the IV to the IMV. The IMV is subsequently wrapped by a membrane cisterna derived from the trans Golgi network, to form the intracellular enveloped virus (IEV). I show that the IEV can co-opt the actin cytoskeleton of the host cell in order to induce the formation of actin tails which extend from one side of the virion. These actin tails propel the virus particle, both intra- and intercellularly, at speeds of up to 2.8µm/min. On reaching the plasma membrane, the virus particles project out from the cell surface at the tip of virally induced microvilli. The outer membrane of the IEV is thought to fuse with the plasma membrane at the tip of these projections, thus exposing the second infectious form of vaccinia. This is thought to be the means by which the cell-associated enveloped virus is presented to neighbouring cells, thereby facilitating the direct cell-to-cell spread of virus particles.

Insertion of metal oxides into block copolymer nanopatterns as robust etch masks for nanolithography

Directed self-assembly (DSA) of block copolymers (BCPs) is a prime candidate to further extend dimensional scaling of silicon integrated circuit features for the nanoelectronic industry. Top-down optical techniques employed for photoresist patterning are predicted to reach an endpoint due to diffraction limits. Additionally, the prohibitive costs for “fabs” and high volume manufacturing tools are issues that have led the search for alternative complementary patterning processes. This thesis reports the fabrication of semiconductor features from nanoscale on-chip etch masks using “high χ” BCP materials. Fabrication of silicon and germanium nanofins via metal-oxide enhanced BCP on-chip etch masks that might be of importance for future Fin-field effect transistor (FinFETs) application are detailed.