Production of helper-dependent adenovirus vector relies on helper virus structure and complementing

✍ Scribed by Heshan Sam Zhou; Tiejun Zhao; X. Mei Rao; Arthur L. Beaudet

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 379 KB
• Volume: 4
• Category: Article
• ISSN: 1099-498X
• DOI: 10.1002/jgm.301

✦ Synopsis

Abstract

Background

The helper‐dependent (HD) adenoviral (Ad) vector relies on a helper virus to provide viral proteins for vector amplification. HD‐Ad vectors can significantly increase therapeutic gene expression and improve safety. However, the yield of an HD‐Ad vector is generally lower than that of an E1‐deleted first‐generation vector, likely due to the alterations in viral E3 or packaging regions of a helper virus that attenuate its replication and complementing for an HD‐Ad vector.

Methods

To study this question and improve HD‐Ad vector production, we have generated four different helper viruses with a wild‐type or deleted E3 region, and with a relocated __lox__P. We have also constructed a first‐generation vector with a wild‐type E3 region and without the __lox__P site. We compared the replication of these viruses in Cre‐positive and ‐negative cells and studied their complementing for HD‐Ad vector production.

Results

Viruses with deleted E3 formed smaller plaques and produced lower titer compared with viruses containing the E3 region. The site where a __lox__P is inserted can also affect virus replication. Higher yield of HD‐Ad vector was obtained when a helper virus with wild‐type E3 was used. We also showed that deletion of the packaging signal in a helper virus through __lox__P/Cre interaction decreased the viral DNA complementing ability.

Conclusions

Although the E3 region is not essential for adenovirus replication in vivo, deletion of this region attenuates virus replication. Production of HD‐Ad vector can be further improved by modifications in helper virus structure. Copyright © 2002 John Wiley & Sons, Ltd.