Hybrid herpes simplex virus/Epstein-Barr virus amplicon viral vectors confer enhanced transgene expression in primary human tumors and human bone marrow-derived mesenchymal stem cells.
BACKGROUND
Herpes simplex virus type-1 (HSV-1) amplicon vectors are attractive tools for gene transfer because of their large DNA insert capacity, their broad host range of vector transduction and a minimal immune response as a result of the absence of helper viruses during viral packaging. However, the transient gene expression remains a challenge for the translation of HSV-1 amplicon based therapeutic strategies to a clinical setting. Although oriP/EBV nuclear antigen (EBNA)-1 elements of Epstein-Barr virus (EBV) have been successfully employed to achieve prolonged transgene expression, little is known about the stability of the EBNA-1 elements in the context of HSV-1 amplicon viral vectors.


METHODS
We have generated HSV/EBV hybrid vectors expressing the mutant EBNA-1 gene with the luciferase reporter gene bicistronically to enable monitoring of EBNA-1 expression in real-time, both in vitro and in vivo.


RESULTS
The results obtained showed that the HSV/EBV hybrid vectors could mediate high levels of transgene expression (ranging from approximately two-fold to nine-fold) in primary human tumor cells and human bone marrow-derived mesenchymal stem cells compared to the control vector. Prolonged transgene expression could also be observed in primary patient-derived human hepatocellular carcinoma xenografts and in the mouse brain parenchyma up to a period of 17 and 365 days, respectively.


CONCLUSIONS
Taken together, we have demonstrated that these hybrid vectors could be promising tools as carriers of therapeutic genes in mesenchymal stem cells or even provide an alternative non-integrating platform for the generation of induced pluripotent stem cells.
Laboratory of Cancer Gene Therapy, Cellular and Molecular Research Division, Humprey Oei Institute of Cancer Research, National Cancer Centre of Singapore, Singapore.
Kian Chuan
KC
Sia
Wei Kin
WK
Chong
Ivy A W
IA
Ho
Yulyana
Y
Yulyana
Berwini
B
Endaya
Hung
H
Huynh
Paula Y P
PY
Lam
D000818:Animals; D001932:Brain Neoplasms / Q000473:pathology; D006528:Carcinoma, Hepatocellular / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D002678:Chimera; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics / Q000378:metabolism; D005240:Feasibility Studies; D005260:Female; D015870:Gene Expression; D017930:Genes, Reporter; D005822:Genetic Vectors; D005910:Glioma / Q000473:pathology; D006367:HeLa Cells; D006378:Helper Viruses; D004854:Herpesvirus 4, Human / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology; D008297:Male; D059630:Mesenchymal Stem Cells / Q000821:virology*; D051379:Mice; D008819:Mice, Nude; D016513:Mice, SCID; D018139:Simplexvirus / Q000235:genetics*; D014161:Transduction, Genetic; D019076:Transgenes; D023041:Xenograft Model Antitumor Assays / Q000379:methods
D019309:Epstein-Barr Virus Nuclear Antigens