A new vaccine has been found to effectively improve the response to antiretroviral treatment for people living with HIV/Aids.

A phase two clinical trial conducted in South Africa has confirmed that the Tat vaccine against HIV/Aids can effectively improve the response to antiretroviral drugs and the life expectancy of those living with HIV worldwide.

The vaccine was developed at the National Institute of Health of Italy (Istituto Superiore di Sanità, or ISS) by the National Aids Centre.

The vaccine’s creator, Barbara Ensoli, of the ISS, said: “The vaccine was developed to target the HIV protein ‘Tat’, which is produced very early in the infection."

"Tat has a key role in viral replication and progression of the disease by weakening the immune system. By designing a vaccine that included a small amount of the Tat protein we were able to induce an immune response capable of improving the effects of HIV drugs.”

The results of the test were published in scientific journal Journal Retrovirology on Thursday.

The trial, conducted at the clinical research unit of the Sefako Makgatho University in Pretoria, enrolled 200 participants on antiretroviral treatment with undetectable levels of HIV in their blood.

Participants were randomly assigned to two “blinded” groups to receive three injections of the vaccine or placebo one month apart. After 48 weeks of vaccination, the vaccinated participants showed significant increases of CD4(+) T cells over placebo.

The CD4(+) T cells are pivotal players of the immune response against pathogens but are progressively lost during HIV infection, a condition leading to Aids.

Although antiretroviral treatment is very effective at suppressing virus replication, CD4(+) T cells can remain low, particularly in people starting treatment late as still occurs in both developed and developing countries.

With the Tat vaccine, the gain of CD4(+) T cells was particularly significant in participants with low CD4(+) T cells at study entry.

The vaccine acts by inducing protective antibodies capable of neutralising the HIV Tat protein from different viral subtypes, including the A, B and C clades circulating in Asia, Europe, America and Africa.

The trial in South Africa is part of a large co-operation programme with the Department of Health and the Medical Research Council in the fight against HIV/Aids, signed by the governments of Italy and South Africa.

ISS president Gualtiero Ricciardi said the programme represented an example of excellence that had effectively combined the translational clinical research with public health, and promoted innovation and international development.

Department of Health spokesman Joe Maila said: “We welcome any findings by scientists.

“Obviously, South Africa welcomes any development in terms of getting a vaccine for HIV, because it is one of the greatest problems that we have.”

The next phase of the study will be vaccine registration.