Long-term persistence of defective HSV-1 vectors in the rat brain is demonstrated by reactivation of vector gene expression.
Wild-type HSV-1 is known to persist indefinitely in neurons in the latent state; however, defective HSV-1 vectors, or amplicons, contain only approximately 1% of the HSV-1 genome and persistence of these HSV-1 vectors has not been studied even semiquantitatively in the adult rat brain. Defective HSV-1 vectors contain both an HSV-1 origin of replication and a packaging site, and in the presence of helper virus can undergo DNA replication and packaging into HSV-1 particles. Our prototype defective HSV-1 vector, pHSVlac, uses the HSV-1 immediate-early (IE) promoter to regulate expression of the Escherichia coli lacZ gene. Using cultured neuronal cells, we have previously shown that expression from pHSVlac can be augmented by superinfection with a helper virus. In this study, pHSVlac was delivered into the adult rat striatum or hippocampus, and 2-3 months after gene transfer we utilized superinfection with several replication-incompetent HSV-1 mutants to reactivate expression from pHSVlac in approximately 30% of the number of cells observed at 4 days after gene transfer. Thus, HSV-1 plasmid vectors can persist for at least 2-3 months in at least approximately 30% of the cells which are initially infected.
Starr
P A
PA
Department of Neurosurgery, Children's Hospital, Boston, MA 02115, USA.
Lim
F
F
Grant
F D
FD
Trask
L
L
Lang
P
P
Yu
L
L
Geller
A I
AI
D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000821:virology; D002460:Cell Line; D002522:Chlorocebus aethiops; D003342:Corpus Striatum / Q000378:metabolism* / Q000473:pathology / Q000821:virology; D003673:Defective Viruses / Q000235:genetics* / Q000502:physiology; D015870:Gene Expression; D005822:Genetic Vectors; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology / Q000821:virology; D006801:Humans; D051381:Rats; D015163:Superinfection; D014709:Vero Cells; D017735:Virus Latency