Perhaps relatively few people would immediately know what the term adenovirus refers to, but most of us are probably familiar with the effects of a member of this family of viruses, the one that causes the common cold. Although it is rare that these microbes cause permanent damage or death in people with normally-functioning immune systems, they have certainly been a source of human misery for a long time.
The Medical Daily news site has a report on some new research by scientists at the Scripps Research Institute who, in a paper [abstract] published in the August 27 issue of Science, have presented the first detailed description of the structure of an adenovirus, down to atomic scale. The imaging of the crystalline virus was done using X-ray diffraction, giving a resolution of 3.5 angstroms. (One angstrom, abbreviated Å, is one nanometer, or 1 × 10-10 meter.) The virus particles analyzed have a mass of approximately 150 megadaltons, or 150 million times the mass of a single carbon atom, and contain nearly 1 million amino acids. This is the largest such particle analyzed to date.
The team began to work on determining the molecular structure of the virus in 1998; the subsequent project turned out to take much longer than expected. One of their major hurdles was getting the virus into a form which could be crystallized. They developed a variant form of the virus to this end, but eventually also had to use robotic crystallization, which can use samples of solution much smaller than usually possible (samples on the order of 50 nanoliters were used). The work also used a new synchrotron, the Advanced Photon Source 23 ID-D beamline at the Argonne National Laboratory, to achieve the necessary resolution.
This really is a significant accomplishment. Of course, elucidating the structure of the virus may some day help in developing treatments for infections caused by the virus, which would delight cold sufferers everywhere. However, a more important possible benefit relates to the development of genetic therapies. One of the techniques used in this area is the insertion of the genetic material into a suitably benign virus, which then can infect the target cells. Researchers in the field have been interested in the adenovirus family because the virus is fairly hardy and can infect a variety of cell types. A better understanding of the virus’s structure might be of great value in making the therapy more effective, while minimizing side effects.