Meet Adenovirus (not to be confused with adeno-associated virus from last post)!
I have also worked pretty closely with Adenovirus in my scientific career.
Adenovirus (from the family parvoviridae) is 100nm in diameter, non-enveloped, and carries double-stranded DNA. The capsid is made of 720 protein subunits (known as hexons) arranged as an icosahedron. At the 12 icosahedral vertices the viral proteins form a penton base from which a long fiber extends. Each face of the icosahedron is made up of 12 subunits (as opposed to one subunit per face with AAV).
This virus, while still relatively small, has a larger genome (35-36kb) and has been widely investigated as a gene therapy vector and for vaccines. Key portions of the viral genome that allow the virus to replicate (typically E1/E2 and sometimes E3) are replaced with genetic material that acts therapeutically or encodes for an antigen.
Adenovirus, in it’s native form, is able to replicate entirely on its own in human cells and because of this it can cause cold-like symptoms in humans (fever, sore throat, bronchitis, pneumonia, diarrhea, etc.).
In its engineered form (acting as a vector) it cannot replicate and therefore it cannot cause illness.
Adenovirus is currently being utilized to carry the genetic code of the SARS-CoV-2 spike protein by companies such as Johnson & Johnson and Oxford/AstraZeneca. It is also FDA approved as a live virus for creating immunity against itself (Ad4 and Ad7). An adenovirus-based vaccine is also approved for use by the European Commission for use against Ebola. Finally, the very first human studies done with Adenoviruses for gene therapy were almost 3 decades ago.
Posted on Instagram on February 23, 2021.