Viral Expression

Recombinant viruses are excellent tools for the introduction of genetic material into host cells. Each virus differs in how it infects cells and replicates:

Adenoviruses can infect a variety of mammalian cell types with high efficiency. They remain epichromosal upon infection, so they are only suitable for transient expression.
Adeno-Associated Virus (AAV) integrates into the host cell genome at a very specific site in one human chromosome; random insertions are very rare, making it less immunogenic than adenovirus or retrovirus.
Retroviruses (e.g. MMLV) introduce genetic material into the genome of the host cell, allowing long-term stable expression. Retroviral titer is typically lower than that of adenovirus.
Lentiviruses (e.g. HIV-1, FIV, SIV) are a sub-class of retroviruses that can be used for both transient and stable gene expression; they can infect both proliferating and non-proliferating cells.