Shanghai scientists are claiming a breakthrough in the search for an HIV vaccine, with clinical trials on humans expected to begin in three years' time, given sufficient funding.

Scientists from the Institut Pasteur of Shanghai, Chinese Academy of Sciences, say they are the first in the world to use fruit fly cells to produce HIV-1 virus-like particles which then successfully generated immunity in mice.

The HIV-1 virus is the most common strain of HIV viruses.

The scientists' research has been published in the leading Journal of Virology.

Currently, there is no effective treatment for HIV/AIDS. Medicines can only control duplication of the virus, not kill it.

Thus, a safe and effective vaccine is of vital importance if the spread of HIV/AIDS is to be controlled.

However, previous research into HIV vaccines has not gone smoothly.

In 2009, an experimental HIV vaccine developed in Thailand for the first time cut the risk of contracting HIV by 31 percent in humans after failed trials in previous years.

"But that vaccine can't be used for wide-scale injection on humans due to its low protection rate and poor effects on virus load reduction," said Paul Zhou, leading scientist in the Shanghai discovery.

"Concerning the previous researches on HIV vaccine, we decided to stick to the production of HIV virus-like particles," he said.

Virus-like particles resemble viruses, but are non-infectious because they do not contain any viral genetic material.

So far, VLPs have been successfully developed into vaccines for the prevention of infection by the hepatitis B virus (HBV) and the human papilloma virus (HPV), the cause of cervical cancer.

Zhou said that current methods of producing HIV-1 VLPs had many limitations but his team developed a novel strategy to produce them using fruit fly cells.

In the laboratory, mice injected with the HIV-1 VLP developed an immunity against the HIV virus.

Zhou said his team's method of producing the VLPs boded well for the development of a vaccine against HIV-1.

"In the next step, we will do tests on monkeys.

"The success of monkeys will pave the way for clinical trials on human beings."