Some food for thought. If there is a gene that can be switched on, enhanced or synthesized in order to sustain metabolism and extend life for a considerable increase in overall longevity, who gets it? Who will be denied? What if this research got into the wrong hands and a group developed a virus that affected this gene so as to grant longevity to those it didn't kill from flu-like symptoms?
Consider a plague that could make you live for more than a century, if it didn't kill you outright.