A woman signs the condolence book for Dutch AIDS expert Joep Lange and his assistant Jacqueline van Tongeren in the Academic Medical Centre (AMC) in Amsterdam. (Evert Elzinga/EPA)

Delegates at a global AIDS conference vowed Saturday to renew efforts to end the deadly disease in honor of the commitment of colleagues killed when a Malaysia Airlines plane was shot down over Ukraine.

The Malaysia Airlines Boeing 777 was en route from Amsterdam to Kuala Lumpur, Malaysia, on Thursday when it apparently was brought down by a surface-to-air missile in an area of eastern Ukraine where Russia-backed rebels have been fighting government forces.

At least six people on the flight, including Joep Lange, a leader in the field of AIDS research, were heading to the AIDS 2014 Conference in Melbourne, according to the International AIDS Society (IAS), which organizes the event.

The number of conference delegates on the plane was much lower than earlier feared.

Lange’s partner, Jacqueline van Tongeren, who worked for the Amsterdam Institute for Global Health and Development, was also killed along, with two members of the AIDS Action Europe organization, a campaigner for Stop AIDS Now and Glenn Thomas, a spokesman for the World Health Organization.

“This is a moment of deep sadness for the world,” IAS President Françoise Barré-Sinoussi told reporters outside the convention center where the conference is to open Sunday.

“The extent of our loss is hard to comprehend and express. Our colleagues were traveling because of their dedication to bringing an end to AIDS. We will honor their commitment and keep them in our hearts as we begin our program on Sunday.”

Barré-Sinoussi, who won a Nobel Prize for her part in identifying the human immunodeficiency virus (HIV), said there would be a moment of silence during the opening ceremony to remember those who had died.

Tables had also been set up with condolence books for any of the 12,000 expected participants to sign.

Barré-Sinoussi said it was too early to say what effect the loss would have on AIDS research, but said colleagues should work together as a tribute to those who had died.

Inside the conference center, delegates who had traveled from around the world expressed their shock.

Karen Hawke, an Australian PhD student presenting a paper on HIV drug resistance, said she could not believe what had happened.

“It’s taken a lot of excitement out of coming here and hearing about the new research,” she said as she scoured the Internet for information on the identities of passengers on the Malaysian plane.

Clive Ingleby, a British global adviser for health and HIV at the Voluntary Services Overseas development organization, said he expected the conference to “somber and reflective.”

But he believed the deaths would rally the AIDS community.

“The AIDS movement is a resilient movement. Even though there’s deep shock and grief, people will pull together and want to come back stronger. We’ll come out of this with a renewed sense of purpose, if only to honor the people we’ve lost,” he said.

— Reuters