On the stability of sequences inserted into viral genomes

Willemsen, Anouk; Zwart, Mark P

Whereas some sequences inserted into viral genomes are stable, others are clearly not. Although there are some factors that appear to explain these differences, at the end of the day there is still a great deal about the relatively simple question of stability that we do not understand. In contrast, these different outcomes are encouraging, because they suggest that if we understand the process well enough, we can design more stable insertions. For most viruses, strong selective constraints appear to exist against increasing genome size. In natural conditions, this is an impediment for evolutionary innovation by gene duplication or HGT. In laboratory conditions, this is an impediment for expressing a gene of interest by using engineered viral vectors.