WASHINGTON — After a 35-year acting career and with two iconic television characters to her name — Elaine Benes of “Seinfeld” and foul-mouthed Vice-President Selina Meyer — Julia Louis-Dreyfus has been honored with the Mark Twain Prize for lifetime achievement in comedy. On Sunday night at Washington’s Kennedy Center, the 57-year-old actress received a stream of testimonials from celebrities including Jerry Seinfeld, Stephen Colbert and 2010 Mark Twain recipient Tina Fey, touching on the multiple aspects of her career. “We both started comedy in Chicago,” Fey said, paying tribute by tracking the similarities between their lives. “We both moved on to ‘Saturday Night Live.’ We both lost our virginity to Brad Hall,” referring to Louis-Dreyfus’ husband and former SNL cast mate, sitting next to the honoree.