SYDNEY, Nov. 19 (Xinhua) -- A research released on Monday has shed new light on how highly pathogenic influenza viruses such as the deadly bird flu infect humans.

Researchers at Australia's Griffith Institute for Glycomics and the University of Hong Kong have discovered that specific sugar molecules in the respiratory tract (Sialylated O-glycans) are key receptors for influenza viruses and particularly for highly pathogenic strains such as avian flu.

"Our finding sheds new light on how deadly influenza viruses attach to cells that are present in the respiratory tract and the importance of O-glycans has been overlooked so far," lead researcher Associate Professor Thomas Haselhorst said.

"At this stage, our research indicates that a specific region in the avian virus protein called haemagglutinin is structurally well suited to recognize and bind these receptors," Thomas said.

The study opens new avenues for the development of anti-influenza drugs.

"With this knowledge we can enter the next phase and develop novel molecules that mimic these identified O-glycans receptors and block virus binding that would ultimately prevent human infection," Thomas said.

Unlike seasonal influenza, avian flu takes an unusually aggressive course, involving rapid deterioration and a high fatality rate.

Although the virus rarely infects humans and person-to-person transmission is even more rare, if the avian virus evolve to become more contagious, it could present a serious global public health threat.

"We are currently investigating if the binding event to our newly discovered O-glycans could play a role in such an event," Thomas said.