Modest increases in the titers of helper virus-free herpes simplex virus 1 (HSV-1) vectors by packaging in a cell line with inducible expression of HSV-1 VP16 or by treatment with N,N'-hexamethylene-bis-acetamide.
A recently developed helper virus-free HSV-1 vector system has potential for both gene therapy and physiological studies, but relatively low vector titers have complicated use of this system. In this report, we explored improving the vector titers by isolating a Vero cell line that uses the tetracycline-regulated promoter system to induce HSV-1 VP16 at the beginning of the packaging procedure. We isolated the required cell line and demonstrated that it supports enhanced expression from a HSV-1 immediate early (IE) promoter. However, use of this cell line in helper virus-free vector packaging results in only a modest, approximately 2-fold increase in the vector titers. Additionally, treating the packaging cells with N,N'-hexamethylene-bis-acetamide (HMBA), which is known to induce HSV-1 IE promoters, also supports only modest increases in the vector titers. These results suggest that the lack of VP16 is not the rate limiting factor in the packaging procedure.
Sun
M
M
Division of Endocrinology, Children's Hospital, Boston, MA 02115, USA.
Lee
J
J
Yu
L
L
Geller
A I
AI
D000081:Acetamides / Q000494:pharmacology*; D000818:Animals; D002522:Chlorocebus aethiops; D005822:Genetic Vectors / Q000502:physiology*; D006378:Helper Viruses; D017405:Herpes Simplex Virus Protein Vmw65 / Q000378:metabolism / Q000502:physiology*; D018259:Herpesvirus 1, Human / Q000235:genetics / Q000502:physiology*; D014161:Transduction, Genetic; D014709:Vero Cells; D019065:Virus Assembly
D000081:Acetamides; D017405:Herpes Simplex Virus Protein Vmw65; C014026:hexamethylene bisacetamide