Spider silk is one of nature’s toughest substances, similar in strength to the Kevlar plastic found in bulletproof vests but much more flexible. Kraig Biocraft, a company out of Ann Arbor, Michigan, genetically altered silkworms to produce a fiber that’s similar to pure spider silk. Today, they announced an Army contract to test this so-called Dragon Silk for possible use in body armor.
Ref: Silkworms transformed with chimeric silkworm/spider silk genes spin composite silk fibers with improved mechanical properties. Proceedings of the National Academy of Sciences (28 November 2011) | DOI: 10.1073/pnas.1109420109 (Open Access)
The development of a spider silk-manufacturing process is of great interest. However, there are serious problems with natural manufacturing through spider farming, and standard recombinant protein production platforms have provided limited progress due to their inability to assemble spider silk proteins into fibers. Thus, we used piggyBac vectors to create transgenic silkworms encoding chimeric silkworm/spider silk proteins. The silk fibers produced by these animals were composite materials that included chimeric silkworm/spider silk proteins integrated in an extremely stable manner. Furthermore, these composite fibers were, on average, tougher than the parental silkworm silk fibers and as tough as native dragline spider silk fibers. These results demonstrate that silkworms can be engineered to manufacture composite silk fibers containing stably integrated spider silk protein sequences, which significantly improve the overall mechanical properties of the parental silkworm silk fibers.