New discovery on how the body fights dengue fever

December 12, 2011

Worldwide, dengue fever strikes roughly 50 million people every year and takes the lives of thousands, but specific therapies or a vaccine for this mosquito-borne illness remain unavailable. A report coming out in the online journal mBio® on December 13 describes a new discovery about how the body fights the dengue virus, a finding that could explain differences in the ability to fight off the virus and help in developing a drug to boost this response.

Dengue is relatively unknown here in the U.S., but according to the World Health Organization the global incidence of dengue infection has been rising alarmingly in the past decades. Today, 2.5 billion people are at risk from dengue fever and from dengue hemorrhagic fever, a lethal complication of infection. Despite the high infection rates, there are currently no specific treatments for dengue fever and no vaccine to prevent infection with the dengue virus. Many scientists who study the disease have been searching for ways to boost the human immune response to dengue so that it can't gain a foothold in the body.

Researchers from Washington University, Walter Reed Army Institute of Research and the University of Copenhagen, Denmark, report a new finding that a part of the immune system called mannose-binding lectin (MBL) is involved in targeting dengue viruses for destruction. MBL recognizes sugar molecules present on the outsides of many different kinds of viruses and bacteria. When it finds these sugars, MBL activates the complement system, which targets foreign materials in the body for destruction in any of a number of cruel ways. Scientists have known that the complement system takes a hit during dengue infection, but until now no one knew that it was also involved in getting rid of dengue viruses.

"Before, people thought the complement system was involved primarily in pathogenesis," says Sujan Shresta, an Associate Professor at the La Jolla Institute for Allergy and Immunology, who reviewed the paper and was not involved in the work. "This paper is the first to look at the role of the complement system in the context of protection" from the dengue virus, says Shresta.

This is an important discovery in terms of human health, continues Shresta, because different people naturally make different amounts of MBL. Some people have high levels of MBL, some people have low levels, a fact that may help explain why some individuals are able to fight off the virus while others are not.

The authors showed that blood samples with high levels of MBL neutralized dengue more efficiently than samples with lower levels of MBL. This finding suggests that people with high MBL levels in their blood could well be better at fighting dengue infection.

This is a clue that could help scientists create therapies for the disease. "You could develop antivirals that work through a similar mechanism," to deactivate dengue viruses, says Shresta. Vaccines could also be designed to activate this pathway, she says, helping boost the normal functions of the immune system to fight off infection.
-end-
mBio® is an open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. It can be found online at http://mbio.asm.org.

The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.

American Society for Microbiology

Related Immune System Articles from Brightsurf:

How the immune system remembers viruses
For a person to acquire immunity to a disease, T cells must develop into memory cells after contact with the pathogen.

How does the immune system develop in the first days of life?
Researchers highlight the anti-inflammatory response taking place after birth and designed to shield the newborn from infection.

Memory training for the immune system
The immune system will memorize the pathogen after an infection and can therefore react promptly after reinfection with the same pathogen.

Immune system may have another job -- combatting depression
An inflammatory autoimmune response within the central nervous system similar to one linked to neurodegenerative diseases such as multiple sclerosis (MS) has also been found in the spinal fluid of healthy people, according to a new Yale-led study comparing immune system cells in the spinal fluid of MS patients and healthy subjects.

COVID-19: Immune system derails
Contrary to what has been generally assumed so far, a severe course of COVID-19 does not solely result in a strong immune reaction - rather, the immune response is caught in a continuous loop of activation and inhibition.

Immune cell steroids help tumours suppress the immune system, offering new drug targets
Tumours found to evade the immune system by telling immune cells to produce immunosuppressive steroids.

Immune system -- Knocked off balance
Instead of protecting us, the immune system can sometimes go awry, as in the case of autoimmune diseases and allergies.

Too much salt weakens the immune system
A high-salt diet is not only bad for one's blood pressure, but also for the immune system.

Parkinson's and the immune system
Mutations in the Parkin gene are a common cause of hereditary forms of Parkinson's disease.

How an immune system regulator shifts the balance of immune cells
Researchers have provided new insight on the role of cyclic AMP (cAMP) in regulating the immune response.

Read More: Immune System News and Immune System Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.