A sexy vampire, a Manhattan socialite and an indestructible cheerleader walk onto a film set . . . for a good cause!

To mark World AIDS Day 2009 (Tuesday Dec. 1), the hottest young stars of TV and film have joined forces for a new PSA campaign. The sought-after stars of "Coming Together as One" -- which aims to mobilize young people in the fight against poverty and preventable disease like AIDS, TB and malaria -- includes New Moon's Ashley Greene, Kellan Lutz, Nikki Reed and Jackson Rathbone; Gossip Girl's Leighton Meester, Jessica Szohr and Ed Westwick; Heroes' Hayden Panettiere ; 90210's Tristan Wilds; High School Musical's Corbin Bleu; and Star Trek’s John Cho.

The spot was created by director Jesse Dylan, who made last year's popular "Yes We Can" Barack Obama campaign video featuring will.i.am.

The "Coming Together as One" campaign will also help promote the ONE Campus Challenge (OCC) -- a nationwide competition geared towards encouraging students to get involved. Since its August 2007 inception, the OCC has spurred students from over 2500 schools to take 270,000-plus actions (roundtables, rallies, town hall appearances and more) in the fight against poverty.

Says David Lane, President and CEO of ONE: "We know that this generation can help defeat extreme poverty, put more kids in school and protect families from preventable disease."

­ONE is a global advocacy and campaigning organization backed by more than 2 million people from around the world dedicated to the fight against extreme poverty and preventable disease, particularly in Africa. Co-founded by Bono and other campaigners, ONE works closely with policy experts, African leaders, and anti-poverty activists to mobilize public opinion in support of tested and proven methods for tackling poverty and disease. For more information please visit www.ONE.org .