No bigger than a pen, this device filters smallpox, Ebola and other viruses from the blood It is a prospect that terrifies bioweapons experts: Terrorists release smallpox into an American city, spreading sickness and panic. Because the disease is untreatable and vaccines no longer exist, first responders and other emergency personnel would be particularly vulnerable. A new invention, however, may help to avert the worst of this worst-case scenario. Aethlon Medical, a small San Diego biotech company, is developing a portable device that removes viruses from blood. Known as the Hemopurifier, it filters not only smallpox but numerous other viruses,...