Optimisation of herpes simplex virus-based vectors for delivery to human peripheral blood mononuclear cells

Peripheral blood mononuclear cells (PBMCs) represent a significant target for gene delivery both for therapeutic and experimental purposes. Thus far however, it has proved difficult to develop vectors capable of high efficient gene delivery to unstimulated PBMCs. We have tested a range of different vectors derived from herpes simplex virus (HSV) which differ in their degree of disablement in terms of their gene delivery efficiency to unstimulated human PBMCs and ability to deliver a reporter gene. None of the viruses had any significant toxic effect in PBMCs. However, optimal gene delivery to unstimulated PBMCs was obtained with a semidisabled virus lacking functional genes encoding ICP34.5 and Vmw65 which was more efficient than either nondisabled or more extremely disabled viruses. Expression of green fluorescent protein (GFP) with this virus was observed in up to 50% of PBMCs 1 day after infection, and reporter gene expression was detectable by Western blotting and immunofluorescence at undiminished levels at the longest time points tested, up to 5 days after infection. This optimised HSV vector may thus represent an effective tool for gene delivery to unstimulated PBMCs in culture.