The herpes simplex virus amplicon: analyses of cis-acting replication functions

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Herpes simplex virus (HSV) amplicons are defective viral vectors used in gene therapy.
• Previous research indicated that helper virus functions are necessary for amplicon propagation.
• The specific cis-acting elements required for amplicon DNA replication and packaging remained unclear.

Purpose of the Study:

• To identify and map the cis-acting DNA elements essential for herpes simplex virus (HSV) amplicon propagation.
• To determine the precise location of a viral DNA replication origin within the HSV genome.

Main Methods:

• Construction and analysis of deleted derivatives of cloned HSV amplicons.
• Mapping of viral DNA replication origins using standard HSV-1 and HSV-2 genome coordinates.

Main Results:

• Two distinct cis-acting functions, a DNA replication origin and a cleavage/packaging signal, are necessary for amplicon propagation.
• The viral DNA replication origin (ori-2 or oriL) was mapped to coordinate 0.422 of the HSV-1 genome and an equivalent position in the HSV-2 genome.

Conclusions:

• Definitive identification of essential cis-acting elements for HSV amplicon propagation.
• Precise mapping of a key viral DNA replication origin, facilitating the design of improved HSV amplicon vectors.