The monkey is an invaluable model to assess gene transfer in human because of high similarity of its biomedical characteristics and gene structure to those of human. In this study, we examined GFP gene transfer into monkeys using naked DNA, liposome vector, or VSVG-liposome vector and assessed these three conditions. Normal adult crab-eating monkeys (Macaca fascicularis) are used. pCMV was employed as expression vector and green fluorescent protein (GFP) plasmid was inserted into the pCMV to prepare CMV-GFP DNA. DOTAP was mixed with CMV-GFP DNA and used as a non-viral liposome vector(CMV-GFP/liposome). DOTAP containing vesicular stomatitis virus G glycoprotein (VSVG) was also used as another liposome vector(CMV-GFP/VSVG-liposome). Naked DNA(CMV-GFP), CMV-GFP/liposome, and CMV-GFP/VSVG-liposome were intracutaneously injected to monkeys, respectively. Hematological responses and proinflammatory cytokines (TNF, CRP) were assayed. In vivo turnover of GFP DNA was monitored by PCR using a primer set yielding 75-bp product. Expression of GFP protein was observed immnohistochemically

Little change in cell numbers of erythrocytes, leukocytes, and platelets was observed for 9 days after GFP gene transfer (day-9) by the three conditions of naked DNA, CMV-GFP/liposome, or CMV-GFP/VSVG-liposome. No increase in plasma level of TNF or CRP was detected by a sandwich ELISA during the 9 days. Seventy five-bp PCR product was detected frommonkey plasma but not from urine until the 3days after gene transfer (day-3) and its peak was at the next day of gene transfer (day-1), in common, among three conditions. GFP-positve cells were observed at day-1 and reached to peak at day-5. These GFP-positve cells were dendritic cells, resident and exudated macrophages, fibroblasts, or endothelial cells of capillary vessel. Any antibody to GFP did not raise during the 9 days. Thus among three conditions CMV-GFP/VSVG-liposome yielded the most potent expression of GFP protein in monkey.

Among three conditions transferring GFP gene VSVG-liposome vector was the most effective to express GFP protein in monkey model. This VSVG-liposome conditions yielded little side effect to host inflammatory or blood responses.