Adenovirus
Adenovirus vectors have been the second most popular delivery system in gene therapy (with extensive applications in gene therapy for cystic fibrosis and certain types of cancer) and have several advantages as gene livery vectors. They are human viruses which can be produced at very high titres in culture, and they are able to infect a large number of different human cell types including non-dividing cells. Entry into cells occurs by receptor - mediated endocytosis and transduction efficiency is very high (often approaching 100% in vivo). They are large viruses and so have the potential for accepting large inserts.The expression profile with first generation. Ad vectors is not suitable for the long-term correction of chronic diseases but is adequate for direct cell killing, for most immunotherapy strategies and for some acute diseases. The first generation vectors have an insert –size limit of ~7.5kb.

The expression profile with first generation. Ad vectors is not suitable for the long-term correction of chronic diseases but is adequate for direct cell killing, for most immunotherapy strategies and for some acute diseases. The first generation vectors have an insert –size limit of ~7.5kb. The promoter used most frequently with Ad (and indeed all other vectors) is derived from cytomegalovirus(CMV), which gives strong expression in many cell types. Ad gives particularly, efficient gene transfer to the liver, such that dissemination form the site of local injection(such as tumours) and consequent liver transfection is the most serious safety concern. The most serious limitation of Ad vectors stems from their tendency to elicit strong immune and (at high doses) inflammatory responses. Single, large doses of Ad provoke neutralizing antibody response directed to proteins of the viral particle, which prevent binding to target cells and abrogate gene transfer upon repeat dosing by systemic administration routes in animals.

The most advanced of these delivers the wild-type gene for the tumour suppressor P53 for induction of tumour –cell killing. A series of phase II studies is underway, testing this recombinant virus alone and in combination with chemotherapies for the local management of various cancers.The expression profile with first generation. Ad vectors is not suitable for the long-term correction of chronic diseases but is adequate for direct cell killing, for most immunotherapy strategies and for some acute diseases. The first generation vectors have an insert –size limit of ~7.5kb.The expression profile with first generation. Ad vectors is not suitable for the long-term correction of chronic diseases but is adequate for direct cell killing, for most immunotherapy strategies and for some acute diseases. The first generation vectors have an insert –size limit of ~7.5kb.