An HIV vaccine may still be a dream but scientists say that in four to five years they may be able to tell the world which candidate vaccines could successfully be developed into effective ones.

Currently nobody can tell exactly when an effective vaccine will be available for the deadly virus though dozens have been trailed and proved to be ineffective over the past years, an international symposium revealed over the weekend in Beijing.

Robert Gallo, a scientist from University of Maryland Baltimore who participated in the symposium, was the man that proved that the virus now known as HIV causes AIDS. He commented on the difficulties facing the successful development of an HIV preventative vaccine which include the following issues:

Testing cannot use an attenuated live version of the virus or an entire dead version of the virus, forcing the use of subunits of the virus in testing.

There are enormous variations of the virus. Though vaccines can establish antibodies in a person the virus is able to mutate to modify itself, causing the antibody to become ineffective.

HIV is a retrovirus. Therefore it integrates its genes into the cell's genes upon infection complicating vaccine development further.

He called all institutes of human virology throughout the world to take on the responsibility of developing possible vaccines against HIV.

Although nobody can tell exactly which vaccines will be effective, some vaccines exist that are worthy of further research and development, and these need to be identified, he said.

Some of these potentially effective vaccines are being tested and developed in China.

Currently, one vaccine has reached the human test stage for the first time in China, in Guangxi Zhuang Autonomous Region.

Another vaccine, being developed by Shao Yiming, chief expert of the National Center for AIDS/STD, and his followers, has passed the animal test stage and is applying for the human test stage now.

Chinese HIV vaccine research has learned many lessons from the experience of other Chinese experts who have successfully developed vaccines for smallpox and other endemic diseases, Shao said.

More than 150 domestic and overseas scientists gathered at the symposium, which begun on Saturday and lasts until tomorrow, to discuss every possible preventive measure against the virus which now infects nearly 40 million people worldwide.

Besides the development of a vaccine, other preventive measures have been proposed by experts at the symposium such as public education, the issuance of clean needles, and methadone administration to encourage drug users to receive drugs from a safer and cleaner source.

By the end of this year, it is hoped that 128 stations will have been established in the country, with the role of administering free methadone to drug users in a clean and controlled environment to reduce the chance of HIV infection among drug users, Hao Yang, vice director of the Disease Control Department of the Ministry of Health, told China Daily.

Meanwhile, China should encourage people to take HIV tests, in particular among blood donors, to prevent the spreading of the disease through blood transfusions, said Robert Gallo.

In China, at least 23 percent of the total reported HIV/AIDS sufferers are infected through receiving contaminated blood in hospitals.

(China Daily December 5, 2005)