The team at Barcelona's Clinic Hospital has been developing the vaccine for the past five years. It's therapeutic and aimed at treating, rather than preventing the disease.

 

　　Scientists all over the world are trying to develop therapeutic HIV vaccines. Gatell believes the one he and his colleagues are working on is showing great promise.

 

　　Gatell's team tested the vaccine on randomly selected HIV positive patients who were being medicated with antiretroviral medicines. The aim was to discover if they could encourage the patient's own immune system to fight the HIV.

 

　　Gatell says, the most common form of HIV uses dendritic immune cells, to spread its infection.

 

　　"With HIV the problem is that dendritic cells confront the immune system with live and viable viruses which end up destroying it."

 

　　Doctors found that by sending a deactivated virus from an HIV patient to this cell dramatically reduces the level of infection although even with reduced levels of HIV patients will still need to ensure they use protection to prevent the risk of transmitting the disease. The problem is that this therapy isn't permanent.

 

　　After a year most of the patients on the trial had to return to taking their antiretroviral drugs. Gatell argues the trial has shown that in principal a vaccine can be effective:

 

　　"To sum it up briefly the vaccine prototype we have used in our last study in 2013 is not capable of preventing the reappearance of the viral load when the treatment ends. But it reduces the reappearance of the virus between ten and fifteen times. And this is a conceptual proof that a therapeutic vaccine could work."

 

　　The vaccine has to be custom made for each patient. The goal of the team is to develop a vaccine which is an effective cure and will enable patients to stop taking the expensive antiretroviral medicines which keep them alive.

 

　　According to official statistics released by the autonomic government of Catalonia there are some 140,000 HIV positive men and women in Spain, 30,000 of them in Catalonia.

 

　　The scientists at Hospital Clinic are also working on a second vaccine which aims to neutralize antibodies.

 

　　In the past attempts to develop this type of vaccine haven't been successful because the virus is so successful at mutating.

 

　　But Dr. Eloisa Yuste, a former researcher at America's Harvard University says:

 

　　"Putting it in context this is a type of vaccine that has already worked for other infectious diseases that are today being used worldwide. We are already in the development stage. We have already conducted some experimental tests on animals. And in three to five years time we hope we will start tests on humans."

 

　　HIV and AIDS are often associated with the homosexual community. Barcelona has one largest and most diverse gay and lesbian communities in Europe. According to official statistics a quarter of the gay men in town are HIV positive.

 

　　In October this year, 1,500 HIV/AIDS scientists and researchers will gather in the capital of Catalonia to discuss the latest developments in treatment.

 

　　For CRI, I am Li Dong.