Nabi Says Vaccine Helped Smokers Quit  CHICAGO (Reuters) - Nabi Biopharmaceuticals &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=NABI.O target=/stocks/quickinfo/fullquote"&gt;NABI.O&lt;/A&gt; on  Tuesday said its NicVAX nicotine vaccine showed promise in  helping smokers quit smoking in a small clinical trial, sending  its shares up 17 percent.