Background and Aims:The hepatitis C virus (HCV) receptor CD81 is over-expressed on peripheral blood mononuclear cells (PBMC) in patients chronically infected with HCV and declines during antiviral therapy.Aim of the present study was to prospectively investigate CD81 expression on PBMC subtypes for early discrimination S328

of nucleic acid in humans.However, these devices require moving parts and electricity that limits the ease by which they can be used.To solve this problem we have now developed a simple and robust injection needle that takes advantage of the fact that pores opens in cellular membranes when the hydrostatic pressure in the tissue increases, termed In vivo Intracellular Injections Needle (IvIn) technology.Methods: The basic design of the IvIn device uses 1 to 5 circularly oriented needles where the ends of the needles have been sealed by laser welding.New openings (5-40) of various sizes have been made on the needle shaft that directs the injected liquid centrally in the circle of needles.Finally, one or more needles have been positioned centrally with openings in all directions.Results and Conclusions: Our data show that injection of a naked plasmid DNA encoding hepatitis C virus non-structural 3/4A (NS3/4A) proteins in rabbit tibialis anterior muscles leads to a subsequent higher number of in vivo transfected muscle cells that express the transferred gene.The IvIn technology also results in an improved local inflammation at the site of injection, which may help in recruiting immune cells to the injection area.The improved NS3/4A-DNA uptake, antigen expression and local inflammation resulted in that T cell responses to the expressed transgene can be detected already five days post immunization.Importantly, the new in vivo intracellular injections needle can be used with any commercially available syringe and does not require any advanced knowledge in injection techniques.Thus, we believe that the IvIn technology can offer a simple solution for gene transfer in vivo in larger animals, hopefully also including humans.