construction of various γ34.5 deleted fluorescent-expressing oncolytic herpes simplex virus type 1 (ohsv-1) for generation and isolation of hsv-based vectors

background: oncolytic herpes simplex virus (ohsv) vectors lacking γ34.5 has demonstrated anticancer effects without affecting normal cells. therefore, they are considered as ideal templates to construct efficient vectors for tumor targeting and cancer gene therapy. herein, we reported construction of three single/dually-labeled recombinant hsv-1 vectors, which provide an opportunity to replace each γ34.5 with a distinct gene and to easily select them with fluorescent microscopy. methods: generation of recombinant viruses was performed with conventional homologous recombination methods using green fluorescent protein (gfp) and blecherry harboring shuttle vectors. viruses were isolated by direct fluorescence observation and standard plaque purifying methods and confirmed by pcr and sequencing and flow cytometry. xtt and plaque assay titration were performed on vero, u87mg, and t98 gbm cell lines. result: we generated three recombinant viruses, hsv-gfp, hsv-gr, and hsv-red. the hsv-gfp showed two log higher titer (1010 pfu) than wild type (108 pfu). in contrast, hsv-gr and hsv-red showed one log lower titer (107 pfu) than parental hsv. cytotoxicity analysis showed that hsv-gr and hsv-red can lyse target tumor cells at multiplicity of infection of 10 and 1 (p<0.001). moreover, hsv-gfp showed higher infection potency (98%) in comparison with hsv-gr (82%). conclusion: our ohsvs provide a simple and an efficient platform for construction and rapid isolation of 2nd and 3rd generation ohsvs by replacing the inserted dyes with transgenes and also for rapid identification via fluorescence activated cell sorting. these vectors can also be used for tracing the efficacy of therapeutic agents on target cells, imaging of neural or tumoral cells in vitro/in vivo and as oncolytic agents in cancer therapy.