A new designer protein may hold the answer to HIV prevention as an alternative to a traditional vaccine. A team of researchers headed by the Scripps Research Institute in Florida (USA) have discovered a way of ‘deactivating’ the replication of HIV within the human body for several months after administering the protein.

HIV AIDSThis is not a new concept. Many antiretroviral drugs (ARVs) work in much the same way. By preventing the virus from entering host cells, new viruses cannot be produced. As a result the HIV infection cannot spread to destroy more immune cells and make the body prone to infections that can eventually lead to death.

However, the new protein goes a step further. It offers protection for up to 8 months after it has been administered and has thus far shown to be effective in blocking every strain of HIV-1 and HIV-2. According to team leader Professor Michael Farzan, the project is a culmination of work that has extended over a decade.

Blocking the HIV ‘Factory’

HIV (human immunodeficiency virus) is a single-strand RNA virus. When it attaches to a host cell, the virus injects its genetic material into the cell thereby making it into an ‘HIV factory’. The virus attaches to specific receptors on the host cell known as the CCR5 and the Scripps Research Institute team worked on blocking this ‘locking’ mechanism.

As yet there is no cure for HIV despite the advances with antiretroviral drugs in the past two decades. This new protein is not a cure either. With repeated failed attempts at producing a viable HIV vaccine, it was believed that the alternative would be to focus on antibodies that would direct the immune system against HIV.

Vaccines work by stimulating the body to produce these antibodies that can then target the virus should it ever enter the body. For some infectious diseases where vaccines are not available or ineffective, antibodies may be administered to facilitate the same protective mechanism.

However, HIV vaccines to date have failed and HIV antibodies do not neutralize all strains of the virus. The new protein developed by the Scripps Research Institute joint team appears to have overcome these failures and obstacles.  The protein attaches to the virus particles that need to ‘lock’ with the receptor on the human host cell to facilitate entry.

Is it a vaccine?

In the traditional sense of the word, a vaccine is made from natural particles of the organism to stimulate the body’s immune defences. As a result the immune system ‘learns’ how to respond to the threat before it is exposed to it. The new protein does not work in this way. It attaches to the virus thereby rendering inactive to enter the host cell, replicate an destroy it in the process.

Nevertheless the protein has the same benefits as a vaccine in terms of protecting a person for an extended period of time after being administered. But it is still early days and the fight against HIV is far from being won. New aggressive strains of HIV quickly find alternate receptors to attach to which most strains cannot do in a short period of time.

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