this technology is now being used to investigate novel vaccine strategies. the ability to synthesize viruses has far-reaching consequences, since viruses can no longer be regarded as extinct, as long as the information of their genome sequence is known and permissive cells are available. as of march 2014, the full-length genome sequences of 3,843 different viruses, including the smallpox virus, are publicly available in an online database maintained by the national institutes of health. synthetic viruses have also been researched as potential gene therapy tools.