Novel gene therapy viral vector using non-oncogenic lymphotropic herpesvirus

• Published in: PloS one Vol. 8; no. 2; p. e56027
• Main Authors: Shimizu, Akihiro, Kobayashi, Nobuyuki, Shimada, Kazuya, Oura, Kuniaki, Tanaka, Tadao, Okamoto, Aikou, Kondo, Kazuhiro
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11-02-2013; Public Library of Science (PLoS)
• Subjects: B cells; Biology; Blood; Blood & organ donations; Blood cells; Carcinogens; CD4 antigen; CD8 antigen; Chromosomes; Cord blood; Cytomegalovirus; Cytopathogenic Effect, Viral; Defects; Dendritic cells; Deoxyribonucleic acid; DNA; DNA biosynthesis; Gag protein; Gene Expression; Gene Expression Regulation; Gene Order; Gene therapy; Genes; Genetic engineering; Genetic Therapy; Genetic vectors; Genetic Vectors - genetics; Genome, Viral; Genomes; Gynecology; Health risk assessment; Herpes viruses; Herpesvirus 6, Human - genetics; HIV; Human immunodeficiency virus; Humans; Immunological diseases; Immunotherapy; Infections; Interferons - pharmacology; Leukocytes, Mononuclear - drug effects; Leukocytes, Mononuclear - metabolism; Leukocytes, Mononuclear - virology; Lymphocytes; Lymphocytes - metabolism; Lymphocytes - virology; Lymphocytes T; Macrophages; Malignancy; Medicine; Obstetrics; Peripheral blood; Proteins; Replication; RNA Interference; T cells; Transgenes; Umbilical cord; Vectors (Biology); Viral Tropism; Virology; Virus Replication; Viruses; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0056027

Despite the use of retroviral vectors, efficiently introducing target genes into immunocytes such as T cells is difficult. In addition, retroviral vectors carry risks associated with the oncogenicity of the native virus and the potential for introducing malignancy in recipients due to genetic carryover from immortalized cells used during vector production. To address these issues, we have established a new virus vector that is based on human herpesvirus 6 (HHV-6), a non-oncogenic lymphotropic herpesvirus that infects CD4(+) T cells, macrophages, and dendritic cells. In the present study, we have altered the cell specificity of the resulting recombinant HHV-6 by knocking out the U2-U8 genes. The resulting virus proliferated only in activated cord blood cells and not in peripheral blood cells. Umbilical cord blood cells produced replication-defective recombinant virus in sufficiently high titer to omit the use of immortalized cells during vector production. HHV-6 vectors led to high rates (>90%) of gene transduction in both CD4(+) and CD8(+) T cells. These viruses showed low-level replication of viral DNA that supported greater expression of the induced genes than that of other methods but that was insufficient to support the production of replication-competent virus. Furthermore, HHV-6 vectors containing short hairpin RNAs against CD4 and HIV Gag remarkably inhibited the production of these proteins and HIV particles. Here we demonstrate the utility of HHV-6 as a new non-carcinogenic viral vector for immunologic diseases and immunotherapy.