SYDNEY, Feb. 21 (Xinhua) -- Australian researchers have come a step closer to understanding how the human immunodeficiency virus (HIV) evades the immune system.

The "unexpected" discovery, published by Monash University on Tuesday, is an important step in defeating HIV.

HIV has been responsible for more than 39 million deaths in the last 30 years and remains one of the world's most significant public health challenges.

Researchers from Monash, in a joint effort with a team from Cardiff University in the United Kingdom (UK), demonstrated how HIV mutations can lead to key immune molecules, known as the Major Histocompatibility Complex (MHC), differently displaying fragments of the virus and how it can cause the virus to remain "hidden" from the immune system.

Julian Vivian, the principal author of the study, said the team had not yet developed a complete understanding of how HIV outmanoeuvred the immune system.

"This work uncovers a novel mechanism for HIV immune escape, which will be important to incorporate into future vaccine development and may have broader implications for immune recognition of MHC molecules," Vivian said in a media release on Tuesday.

The finding is the first significant discovery since Monash and Cardiff University's signed a Memorandum of Understanding (MoU), a five-year agreement that will see the two institutions collaborate on a series of studies.

Jamie Rossjohn, a Molecular Imaging professor at Monash, said the finding was exciting and unexpected.

"These result were only possible because of the close collaborative ties between Monash and Cardiff researchers," Rossjohn said.