Microsoft Corp chairman Bill Gates has so much experience with bugs that he is diversifying into engineering a few of the things: he is the largest shareholder, with 10%, in a new Seattle biotechnology company, Icos Corp, which plans to develop biological and pharmaceutical products for rheumatoid arthritis, multiple sclerosis, asthma and other inflammatory diseases; Gates also holds rights to buy another 10% of Icos at market prices during the next 10 years; it has raised $33m in venture funding altogether.