Preparation of a Bacteriophage T4-based Prokaryotic-eukaryotic Hybrid Viral Vector for Delivery of Large Cargos of Genes and Proteins into Human Cells.

A viral vector that can safely and efficiently deliver large and diverse molecular cargos into cells is the holy grail of curing many human diseases. Adeno-associated virus (AAV) has been extensively used but has a very small capacity. The prokaryotic virus T4 has a large capacity but lacks natural mechanisms to enter mammalian cells. Here, we created a hybrid vector by combining T4 and AAV into one nanoparticle that possesses the advantages of both. The small 25 nm AAV particles are attached to the large 120 nm x 86 nm T4 head through avidin-biotin cross-bridges using the phage decoration proteins Soc (small outer capsid protein) and Hoc (highly antigenic outer capsid protein). AAV thus "piggy-backed" on T4 capsid, by virtue of its natural ability to enter many types of human cells efficiently acts as a "driver" to deliver large cargos associated with the T4 head. This unique T4-AAV hybrid vector approach could pave the way for the development of novel therapeutics in the future.