Gene transfer using human polyomavirus BK virus-like particles expressed in insect cells

The major structural protein (VP1) of the BK polyomavirus (BKV) was express ed in the recombinant baculovirus expression system. Recombinant BKV VP1 wa s shown to self-assemble into virus-like particles (VLPs) with a diameter o f 45-50 rim. As for other polyomaviruses, BKV VP1 has the capacity to bind to exogenous DNA. Furthermore, the potential of BKV VP1 VLPs was investigat ed for gene transfer into COS-7 cells using three methods for the formation of pseudo-virions: disassembly/reassembly, osmotic shock and direct intera ction between VLPs and reporter plasmid DNA. The latter method was shown to be the most efficient when using linearized plasmid. Gene transfer efficie ncy with BKV pseudo-virions was of the same order as that observed with hum an papillomavirus type 16 L1 protein VLPs. In addition, it is demonstrated that cellular entry of BKV pseudo-virions is dependent on cell surface sial ic acid.