The system requires the use of six different recombinant baculoviruses each coding for one of the six protein involved in HSV-1 capsid formation. HSV-1 capsids form spontaneously when the six extracts are mixed. We are now studying the time course of capsid formation in this system to identify morphogenetic intermediates in the assembly process. It isexpected that the structure and composition of such intermediates and the times they appear in reaction mixtures will suggest the basic features of the overall assembly pathway. Assembly intermediates are being isolated from reaction mixtures by sucrose density gradient ultracentrifugation and analyzed by electron microscopy and SDS-polyacrylamide gel electrophoresis.
Studies are also in progress to carry out capsid assembly in vitro beginning with purified proteins.
Finally, we are continuing our studies to confirm the proposed locations of VP19, VP23and VP26 in the capsid shell by using an approach involving specific antibodies and high resolution electron microscopy. Specific monoclonal antibodies are being raised to each of the three proteins and bound to HSV-1 capsids.