In May 2017, the University of Copenhagen’s Faculty of Health and Medical Sciences announced an important breakthrough that may help pave the way for a vaccine against Human Immunodeficiency Virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS). The revolutionary technique represents a new approach to vaccine design.
Although many important drugs have been developed that help individuals with HIV infection live longer, healthier lives, the infection still cannot be cured. Furthermore, the infection cannot be prevented with any existing vaccines. The medication known as PreP, in the form of a pill that must be taken daily, can help prevent HIV infection in those most at risk of contracting it, but even this medication is not 100% effective.
Vaccines have long been used against acute illnesses such as chicken pox, measles, polio, rubella, seasonal influenza, and tetanus. Chronic infectious diseases such as HIV have been much more difficult to vaccinate against, and so far no HIV vaccine has been wholly successful. More monetary resources have been dedicated to finding an HIV vaccine against the infection than to any other vaccine research campaign in history, yet success still seems to elude researchers.
The new HIV vaccine approach strengthens the part of the immune system that attacks the genes of the virus itself. Once a person contracts an HIV infection, this part of the immune system would usually be at its least active. Whereas most vaccines stimulate a strong, short-term reaction of the immune system to the target virus, this innovative approach works by triggering the immune system to slowly, but steadily, attack the virus.
Researchers used this approach on an experimental vaccine against the Simian Immunodeficiency Virus (SIV), which infects monkeys. Their experiments showed the technique to be an effective tool in combating the spread of SIV infection. Researchers hope that a similar technique can be applied to HIV with a similar result.
HIV is a lentivirus, a member of a subgroup of viruses known as retroviruses. These viruses generally have a long incubation period and cause long-term, progressive illnesses in human beings and a variety of other species. Because it attacks the living cells of the immune system, the HIV virus causes the body’s immune system to break down over time, allowing certain cancers and infections to gain a foothold in the body. Without intensive medical treatment, the average life span of someone infected with HIV is 9-11 years.
One of the reasons that HIV has been notoriously difficult to vaccinate against is that the virus mutates rapidly. This creates a high degree of genetic variability among the different strains of HIV, making it difficult for researchers to create an HIV vaccine able to target all the variations of the virus. SIV is similar in that different species of monkeys can become infected with different strains of the simian virus. A strategy that activates the body’s own immune system to combat the infection goes around this problem.
Vaccines for human use typically take many years to develop. After effectiveness has been demonstrated in animal studies, researchers take the vaccine through three phases of clinical trials in healthy human volunteers. These studies begin with a small group of volunteers who are asked to continue using safer sex practices and are not deliberately exposed to the HIV virus (which, of course, would be deeply unethical). If the small study continues to demonstrate effectiveness, researchers try to vaccine out on a volunteer group of a few hundred people, and then if effectiveness can still be shown the vaccine is tested on a volunteer group that numbers in the thousands.
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