President of the International AIDS Society (IAS) Francoise Barre-Sinoussi from France (2nd R) and other delegates observe a moment of silence during the opening of the 20th International AIDS Conference at the Melbourne Convention and Exhibition Centre (MCEC) in Melbourne, Australia, on July 20, 2014. At least six delegates heading for Melbourne to join the 20th international AIDS conference were killed in the crash of Malaysian flight MH17. (Xinhua/Xu Yanyan)

　　A conventioner reacts at a silent tribute during the opening of the 20th International AIDS Conference at the Melbourne Convention and Exhibition Centre (MCEC) in Melbourne, Australia, on July 20, 2014. At least six delegates heading for Melbourne to join the 20th international AIDS conference were killed in the crash of Malaysian flight MH17. (Xinhua/Xu Yanyan)

　　Conventioners react at a silent tribute during the opening of the 20th International AIDS Conference at the Melbourne Convention and Exhibition Centre (MCEC) in Melbourne, Australia, on July 20, 2014. At least six delegates heading for Melbourne to join the 20th international AIDS conference were killed in the crash of Malaysian flight MH17. (Xinhua/Xu Yanyan)