Researchers at John’s Hopkins have been working with human immunodeficiency virus (HIV) that is modified to help the immune system recognize the virus and fight it off. Their report, published in the online journal Blood suggests that this research could be a significant step in the development of a vaccine against HIV.
HIV is a virus that targets specific cells in the immune system. Normally, when a virus invades the body the immune system recognizes it as a potential threat and releases chemicals called interferons to warn the rest of the body to defend against the invader. Standard HIV creates such an overwhelming response from the immune system that it releases too many interferons which confuses the defense system and prevents the body from fighting off the virus.
HIV is a string of genetic code inside a carrier that has the ability to attach to and invade cells in the immune system. When the cell is invaded, it becomes a factory to produce multiple copies of the HIV code which is then released into the body, allowing HIV to spread quickly through the immune system.
The human immunodeficiency virus is carried inside a protective coating that contains large amounts of cholesterol. The Johns Hopkins researchers recognized that when immune system cells (white blood cells) contain smaller amounts of cholesterol than normal, HIV was not able to infect them. The researchers used a chemical to remove the cholesterol from the coating on the HIV, creating altered HIV. When placed with human immune cells in a culture dish, the altered HIV did not trigger the release of interferons like normal HIV did.
The lack of excessive interferons allowed the immune system to react as it would with any other virus at the first encounter. This normal response allows the immune system to recognize a potential threat and create defenses to destroy the invader and to remember it as a threat the next time it enters the body. This is the basis of how vaccines are created. Doctors introduce non-active or weakened virus such as for the flu into the body to allow the creation of antibodies in advance of a real attack from the full-strength virus.
The research team also tested the altered HIV in blood samples that had already been infected by HIV and in samples that had been exposed to HIV but had not become infected. As they expected, blood that was already infected did not mount a defense against the altered HIV. But the blood that had been exposed but not infected was able to recognize the altered HIV as a threat and react to fight off the virus.
The researchers said the altered HIV acted to defeat the properties of HIV that allow it to suppress the immune system. The modified virus also jump-started the immune system’s reaction to defend against the virus. This is a critical step in the development of a vaccine.
In order for a vaccine to work, the body must recognize the threat and build immunity against it. Standard HIV defeats this process by decreasing the immune system’s ability to recognize the virus as a threat, thereby preventing the buildup of immunity. The researchers are hopeful this study will provide new direction for future research into drugs to attack the coating around the HIV virus as a way to allow the immune system to recognize and defend against it.
Sources:
Science Daily. Hide-And-Seek: Altered HIV Can’t Evade immune System. Web. October 12, 2011.
http://www.sciencedaily.com/releases/2011/09/110928105909.htm
Human Immunodeficiency Virus. Medicine.net. Web. October 12, 2011.
http://www.medicinenet.com/human_immunodeficiency_virus_hiv_aids/page3.htm
How Stuff Works. How Your Immune System Works. Web. October 12, 2011.
http://science.howstuffworks.com/environmental/life/human-biology/immune-system3.htm
Centers for Disease Control and Prevention. Basic Information about HIV and AIDS. Web. October 12, 2011.
http://www.cdc.gov/hiv/topics/basic/index.htm
News Medical. What are Vaccines?. Web. October 12, 2011.
http://www.news-medical.net/health/What-are-Vaccines.aspx
Reviewed October 13, 2011
by Michele Blacksberg RN
Edited by Jody Smith