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Llama

Llamas spit, kick, bite … and help cure AIDS. According to recent research, llamas have a secret weapon that might just be the answer to HIV infections that lead to AIDS. As of 2011, there were 33 million people infected with the virus globally, and numbers keep climbing. Currently, not vaccine exists, and the treatment in place doesn’t cure AIDS but merely provides relief from its symptoms and delays it progression. (4)

 

HIV evades the immune system

During an infection, the body reacts by activating its immune cells and releasing antibodies to neutralise the invading agent. However, HIV infects, kills, mutates and hides from those immune cells making it near invisible to our defences. A vaccine works by inducing a pre-emptive immune response characterized by antibodies selectively targeted against a pathogen, so that when the real thing comes along, the body is prepared. (3)

Until recently, all prospects for an AIDS vaccine came to nothing – that is until the llama came along. Many known neutralising antibodies target the specific part of the HIV virus that binds to the CD4 receptor of human immune cells, preventing the virus from binding to and entering the cell. However, according to structural studies, that same binding site is present in a narrow groove that most antibodies can’t reach. (3)

Small llama antibodies stop HIV infections

Human and most mammals have antibodies formed of two heavy chains associated with two light chains. Llamas are an exception. They have those bulky antibodies but also possess another special type, formed of only two long chains. These smaller do a better job of latching onto the receptors on the human cells that HIV vaccines hope to target. (2)

By vaccinating llamas, the researchers found they produced several types of these small antibodies, each targeting a different parts of the CD4 binding site of the virus. They found, that unlike the bulkier antibodies, these different antibodies didn’t compete or cancel out each other’s effects, a common problem for HIV researcher, but rather worked together. The combined four antibody types discovered in llamas were capable of neutralizing all 60 of the different HIV strains the scientists tested them against.

How to use llama antibodies in humans

Humans can’t produce the small llama-type antibodies but these could be produced externally and injected as a medical treatment. However, researchers are concerned humans could have a bad reaction to them. The safety and efficacy of these antibodies would have to be thoroughly tested before they could be used on humans. (1)

One way of getting llama antibodies into humans without an adverse reaction would be by genetically editing them. It wouldn’t be the first time an animal antibody was genetically modified to be more “human friendly”. Recently, two Americans were given humanised mouse antibodies to fight Ebola. The humanisation process reduces the risk of cross-species reaction. (1)

The four small antibodies were found in all tested llamas but only at a very low concentration in the blood so that the llamas had the possibility of fighting HIV but didn’t have enough antibodies to do so effectively, even after repeated rounds of vaccination. These results give hope for the creation of a vaccine against HIV that is tolerated and effective in humans but only after more work is done.  



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