[1] Univ Washington, Obstet & Gynecol, Seattle, WA 98195 USA
[2] Fred Hutchinson Canc Res Ctr, Vaccine & Infect Dis Div, Seattle, WA 98104 USA
[3] Univ Washington, Med, Seattle, WA 98195 USA
[4] Fred Hutchinson Canc Res Ctr, Human Biol Div, Seattle, WA 98104 USA