© 1999 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999

10.4.2.4 Mechanical Virucide

Viruses are acellular bioactive parasites that attack virtually every form of cellular life. Viruses have diameters²¹⁴⁸ ranging from 16-300 nm -- for example, poliomyelitis ~18 nm, yellow fever ~25 nm, influenza ~100 nm, herpes simplex and rabies ~125 nm, and psittacosis ~275 nm.⁷⁵¹ Their shape is either pseudospherical with icosahedral symmetry, as in the poliomyelitis virus, or rodlike, as in the tobacco mosaic virus (TMV). Viruses consist of a core of RNA (most plant viruses and animal viruses such as the rhinoviruses, polio and flu viruses, and all retroviruses) or DNA (most bacterial and some animal viruses), but never both. This nuclear material is surrounded by a protein coat called a capsid, a quasi-symmetrical structure assembled from one or only a few protein subunits called capsomeres. A virus surrounded only by capsid is a naked virus; some viruses acquire a lipid membrane envelope from their host cell upon release, and are called enveloped viruses. Attached to the capsid are other protein structures necessary for host infection, especially attachment or docking proteins. The interior capsid volume is usually only slightly larger, and never more than twice as large, as the volume of the enclosed nuclear material.⁹⁹⁷ For instance, the adenovirus (one family of viruses that causes the common cold in humans) is an icosahedral particle ~70 nm in diameter (~180,000 nm³) containing one double-stranded DNA molecule ~11 microns (~35,000 bases or ~10⁷ daltons) in length (~15,000 nm³), giving a composition of approximately 92% protein and 8% DNA by volume. By comparison, the TMV has 5% nucleic acid, the bushy stunt virus 17%, and the tobacco ringspot virus has 40%.⁷⁵¹

There are at least two methods by which such viruses may be eliminated from the human body, as follows.

Last updated on 24 February 2003