by Cindy Petersen

The ABC of HIV

New developments aim to break down the virus

Medical professionals are working toward zero new infections
New scientific breakthroughs for HIV treatment

RV144 was the name given to a six-year HIV vaccine study carried out in Thailand in 2009. Conducted among 16 000 HIV-negative men and women, the trial found that HIV infection rates were 31% lower among participants who received the vaccine than in those who had not. 

Even though the results were encouraging, they fell short of the minimum 50% prevention rate required to slow the epidemic, which afflicts an estimated 34 million people worldwide.

Now, researchers say they have a better understanding of why the vaccine might have worked – and possible new targets for future vaccines. 

The study found that the vaccine prompted an immune response from four different antibodies. Researchers from Duke University, the United States Military HIV Research Program and the Thailand Ministry of Public Health used data collected from three of the trial’s participants to determine that these antibodies worked on an important site on the surface of HIV infected cells. These antibodies essentially marked infected cells for death by natural killer cells, part of the body’s immune response. 

According to study co-author and Duke Human Vaccine Institute director, Barton Haynes, the findings show the importance of often ignored 'variable' sites on the surface of infected cells for vaccine research. He cautions, however, that researchers cannot say for certain this kind of immune response was the reason behind the Thai trial’s limited success. 

South African researchers might have identified yet another novel vaccine target. They looked at broadly neutralising antibodies that target and bond with specific sugars, blocking the virus from infecting healthy cells. According to Haynes, an ideal HIV vaccine candidate would be able to induce both types of immune responses. 

In a recent development, an Australian scientist has reportedly discovered how to turn the Human Immunodeficiency virus (HIV) against itself to stop it progressing to Aids – describing it as a major breakthrough in finding a cure for the disease.

David Harrich, from the Queensland Institute of Medical Research, says he was able to successfully modify a protein in HIV which the virus needs to replicate, and instead made it 'potently' inhibit virus growth. “I have never seen anything like it. The modified protein works every time,” he says.

Harrich adds that the modified protein, which he has named Nullbasic, showed a 'remarkable' ability to arrest HIV growth in a lab environment and could have exciting implications both in curbing Aids and treating existing HIV sufferers. He describes it as “fighting fire with fire”.

“The virus might infect a cell, but it wouldn't spread,” he says of his study. “You would still be infected with HIV – it's not a cure for the virus – but the virus would stay latent, it wouldn't wake up, so it wouldn't develop into Aids,” he notes.

A person with HIV is said to have Aids when his/her count of CD4 immune system cells drops below 200 per microlitre of blood, or he/she develops what is known as an Aids-defining illness – any one of 22 opportunistic infections or cancers related to HIV.

The majority of people infected with HIV, if left untreated, may not progress to Aids for 10 to 15 years or longer, according to the United Nations. Antiretroviral treatments can prolong this further still.

The new Nullbasic gene therapy, if proven, could see the deterioration from HIV to Aids halted indefinitely, bringing an end to the deadly condition.

“You either have to eliminate the virus infection or, alternatively, you have to eliminate the disease process – and that's what this could do, potentially, for a very long time.”

Animal trials of the protein are due to start this year, with any treatment using it likely to be some years away.

According to the latest UN figures, the number of people infected by HIV worldwide rose to 34 million in 2011 from 33.5 million in 2010. The vast majority (23.5 million) live in sub-Saharan Africa, with another 4.2 million in South and Southeast Asia. There were 1.7 million deaths from Aids-related causes worldwide in 2011, 24% fewer than in 2005 and nearly 6% below the 2010 level.

The UN reported that achieving zero new infections in children was appearing increasingly possible.

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