Sir

Martin Kemp's1 article “Visible viruses” incorrectly credits Brenner and Horne with introducing negative staining and Wildy and Watson with recognizing the parallels between virus structure and Buckminster Fuller's geodesic domes. His discussion of capsid design omits key points.

H. E. Huxley's2 high-resolution study of tobacco mosaic virus made the ‘outline’ of the virus visible, with a clear hole down the middle, saying: “This ‘outlining’ technique ⃛ is so simple and gives excellent contrast and resolution”.

Caspar and Klug's3 comparison of the geodesic domes of Buckminster Fuller to the viral capsid design is discussed by Marks4: “Dr A. Klug and Dr J. T. Finck [sic] ⃛ wrote to Fuller enclosing published reports of their discovery of the icosa-geodesic structuring of the polio virus. In conversations with Fuller ⃛ they intimated that all spherical viruses comprise geodesic arrangements of proteins in systems similar to Fuller's frequency modulated geodesic structures.”

Finally, Kemp asks whether capsid design is constrained by the physical principles underlying macromolecular assemblies, by the principles governing the encoding of design in the genome, or both. The question revolves around function and inheritability — how does the virus genome protect itself in transit between cells?

A simple solution was proposed by Crick and Watson5, who considered how to fit the information for a large container into a small genome. They argued that the repeated use of a single protein to form a symmetric viral capsid could require as little as one gene, making efficient use of genetic information. Today, asymmetrical designs, like those of the cytoskeleton, capture our imagination. Their routes to self-assembly, unlike the pathway described by Lewis Carroll, do not keep “one principle object in view — to preserve its symmetrical shape”.