Thwarting HIV: New Hopes for Vaccination
Developing a vaccine to thwart human immunodeficiency virus (HIV), the virus that causes AIDS, has been a major goal of researchers since the virus was first identified in 1983. There have been many false starts and a few signs of hope, but no real success stories. The latest development in this arena takes an entirely new approach to the problem.
Traditional vaccines rely on injecting a weakened or inactivated version of a virus, or some portion of a virus, into the patient, in hopes of training the patient’s immune system to recognize the virus and be prepared to defend against it in the event of an actual infection. One of the key ways in which the immune system can defend against a virus is by producing proteins called antibodies that recognize portions of the virus particle, bind those recognized portions, and prevent the virus from entering its target cell – rendering the virus harmless, or “neutralizing” it. This approach has not been successful as an HIV immunization strategy, in part because of the high rate of mutation that the virus exhibits – in effect, the immune system is trained to recognize Version One of the virus, and the patient becomes infected with Version Two.
In recent years, various investigators have identified what are referred to as “broadly neutralizing antibodies” – antibodies that are capable of neutralizing a broad range of different HIV strains. These antibodies arise by chance in a minority of HIV-infected individuals, and are thought to be able to recognize multiple strains of the virus because they target regions of the virus that mutate at a much lower frequency than other regions of the virus.
Although these antibodies are highly effective against the virus, they only arise in small number of patients – and only after the infection has already taken root. What if scientists could isolate the genes that provide the instructions for making these antibodies, and deliver them directly to patients – affording the chance to produce their own powerful antibodies capable of defending against multiple strains of HIV, prior to infection?
David Baltimore’s lab at the California Institute of Technology has taken the first steps towards doing just that. Using gene therapy technology, the team introduced the genes that code for these broadly-neutralizing antibodies into muscle cells of mice that have been genetically altered to contain a human immune system – and thus susceptible to HIV. These mice muscle cells then proceeded to make large quantities of the powerful antibodies – rendering the mice resistant to HIV infection. The lab refers to this technique as “vectored immunoprohylaxis (VIP)” – and in the words of Dr. Baltimore, “The advantage of VIP is simply that it works.” After almost thirty years of trying, this is indeed quite an accomplishment. Human clinical trials are expected to begin in 2012.
Baltimore’s work was published in the December 1st 2011 issue of Nature.
Traditional vaccines rely on injecting a weakened or inactivated version of a virus, or some portion of a virus, into the patient, in hopes of training the patient’s immune system to recognize the virus and be prepared to defend against it in the event of an actual infection. One of the key ways in which the immune system can defend against a virus is by producing proteins called antibodies that recognize portions of the virus particle, bind those recognized portions, and prevent the virus from entering its target cell – rendering the virus harmless, or “neutralizing” it. This approach has not been successful as an HIV immunization strategy, in part because of the high rate of mutation that the virus exhibits – in effect, the immune system is trained to recognize Version One of the virus, and the patient becomes infected with Version Two.
In recent years, various investigators have identified what are referred to as “broadly neutralizing antibodies” – antibodies that are capable of neutralizing a broad range of different HIV strains. These antibodies arise by chance in a minority of HIV-infected individuals, and are thought to be able to recognize multiple strains of the virus because they target regions of the virus that mutate at a much lower frequency than other regions of the virus.
Although these antibodies are highly effective against the virus, they only arise in small number of patients – and only after the infection has already taken root. What if scientists could isolate the genes that provide the instructions for making these antibodies, and deliver them directly to patients – affording the chance to produce their own powerful antibodies capable of defending against multiple strains of HIV, prior to infection?
David Baltimore’s lab at the California Institute of Technology has taken the first steps towards doing just that. Using gene therapy technology, the team introduced the genes that code for these broadly-neutralizing antibodies into muscle cells of mice that have been genetically altered to contain a human immune system – and thus susceptible to HIV. These mice muscle cells then proceeded to make large quantities of the powerful antibodies – rendering the mice resistant to HIV infection. The lab refers to this technique as “vectored immunoprohylaxis (VIP)” – and in the words of Dr. Baltimore, “The advantage of VIP is simply that it works.” After almost thirty years of trying, this is indeed quite an accomplishment. Human clinical trials are expected to begin in 2012.
Baltimore’s work was published in the December 1st 2011 issue of Nature.
Labels: AIDS, David Baltimore, gene therapy, HIV, HIV vaccinations, vaccine development
posted by BioTech Primer at
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