Science Current Events | Science News | Brightsurf.com
 

Viral recombination another way HIV fools the immune system

July 22, 2008

Immune system pressure can lead to selection of more potent strains

When individuals infected with HIV become infected with a second strain of the virus, the two viral strains can exchange genetic information, creating a third, recombinant strain of the virus. It is known that the presence of multiple viral strains, called superinfection, frequently leads to a loss of immune control of viral levels. Now a study from the Partners AIDS Research Center at Massachusetts General Hospital (PARC/MGH) shows that how and where viral strains swap DNA may be determined by the immune response against the original infecting strain. Their report will appear in the Journal of Experimental Medicine and has been released online.

"The implication that recombination events are selected by immune responses identifies a new mechanism for the virus to escape the patient's immune system, which would present additional challenges to vaccine design," says Hendrik Streeck, MD, PhD, of PARC/MGH, one of the paper's lead authors. "This finding also has worldwide implications for the development of more complex strains of HIV."

Part of the immune system's response against HIV is carried out by HIV-specific CD8 T cells, also called cytotoxic T lymphocytes (CTLs), which can identify and kill virus-infected cells. Previous PARC/MGH research showed that the effectiveness of the CTL response varies depending on which version or allele of an immune system molecule called HLA Class I an individual has inherited. The current study was undertaken to investigate why an HIV-positive research participant known to have a powerfully protective Class I allele called HLA-B27 began to experience rapid increases in viral levels much sooner than would have been expected.

An examination of blood samples from this individual revealed that his immune response against HIV had predictably controlled the virus for about a year and a half after he was first diagnosed. The effective CTL response was primarily directed against a short segment of the Gag protein typically targeted in HLA-B27 patients.

Analysis after the abrupt increase in viral levels showed that the patient had become infected with a second strain of HIV, and two months later it was found that the two strains had exchanged portions of their Gag sequences initially targeted by his CTLs, allowing the virus to escape from that immune response. The patient's viral loads stabilized for a while but rose again several months later, when it was found that a second HIV mutation that more effectively evades control by HLA-B27 had developed, possibly in response to a second recombination of viral sequences.

"The first Gag recombination event facilitated escape from the primary immune response, shortly after which the immune response recovered to recognize this mutant strain," Streeck explains. "After the second recombination event and emergence of a more potent mutation, there was a dramatic reduction in the CTL response against both versions, leading to a significant increase in viral loads."

Todd Allen, PhD, of PARC-MGH, the study's senior author adds that, while recombination itself appears to be a random event, recombinant strains that are better able to evade the immune system are likely to become dominant through natural selection. He also stresses that even patients whose immune systems can partially control HIV should avoid a secondary infection that could lead to the development of an uncontrollable, recombinant viral strain.

Streeck notes, "Given the growing frequency of recombinant HIV strains worldwide, we need to better understand how immune system pressures may be driving their development and also determine how frequently patients exposed to a second strain of HIV become superinfected." He is a research fellow in Medicine at Harvard Medical School, where Allen is an associate professor of Medicine.

Massachusetts General Hospital


Related Immune System Current Events and Immune System News Articles


Tobacco smoke makes germs more resilient
The mouth is one of the "dirtiest" parts of the body, home to millions of germs. But puffing cigarettes can increase the likelihood that certain bacteria like Porphyromonas gingivalis will not only set up camp but will build a fortified city in the mouth and fight against the immune system.

Ancient anti-inflammatory drug salicylic acid has cancer-fighting properties
Scientists from the Gladstone Institutes have identified a new pathway by which salicylic acid--a key compound in the nonsteroidal anti-inflammatory drugs aspirin and diflunisal--stops inflammation and cancer.

Automating DNA origami opens door to many new uses
Researchers can build complex, nanometer-scale structures of almost any shape and form, using strands of DNA. But these particles must be designed by hand, in a complex and laborious process.

A combined approach to treating metastatic melanoma
Oncologists at the Fred Hutchinson Cancer Research Center have successfully treated a patient with metastatic melanoma by combining two different types of immunotherapy.

Why malnutrition is an immune disorder
Malnourished children are most likely to die from common infections, not starvation. New experimental evidence, reviewed May 26 in Trends in Immunology, indicates that even with a healthy diet, defects in immune system function from birth could contribute to a malnourished state throughout life.

Slime mold reveals clues to immune cells' directional abilities
How white blood cells in our immune systems home in on and engulf bacterial invaders--like humans following the scent of oven-fresh pizza--has long been a mystery to scientists.

Migration back to Africa took place during the Paleolithic
The Palaeogenomics study conducted by the Human Evolutionary Biology group of the Faculty of Science and Technology, led by Concepción de la Rua, in collaboration with researchers in Sweden, the Netherlands and Romania, has made it possible to retrieve the complete sequence of the mitogenome of the Pestera Muierii woman(PM1)using two teeth.

Researchers identify immune genes tied to common, deadly brain cancer
Researchers have identified a group of immune system genes that may play a role in how long people can live after developing a common type of brain cancer called glioblastoma multiforme, a tumor of the glial cells in the brain.

Can Alzheimer's disease-associated peptide fight bacterial infection?
Amyloid-ß is a sticky peptide notorious for forming destructive plaques in the brains of Alzheimer's disease patients, but a new study suggests that it may also serve a protective function as an antimicrobial peptide.

Human amyloid-beta acts as natural antibiotic in the brains of animal models
A new study from Massachusetts General Hospital (MGH) investigators provides additional evidence that amyloid-beta protein - which is deposited in the form of beta-amyloid plaques in the brains of patients with Alzheimer's disease - is a normal part of the innate immune system, the body's first-line defense against infection.
More Immune System Current Events and Immune System News Articles

How the Immune System Works (The How it Works Series)

How the Immune System Works (The How it Works Series)
by Lauren M. Sompayrac (Author)


How the Immune System Works has helped thousands of students understand what’s in their big, thick, immunology textbooks. In his book, Dr. Sompayrac cuts through the jargon and details to reveal, in simple language, the essence of this complex subject. In fifteen easy-to-read chapters, featuring the humorous style and engaging analogies developed by Dr. Sompayrac, How the Immune System Works explains how the immune system players work together to protect us from disease – and, most importantly, why they do it this way. Rigorously updated for this fifth edition, How the Immune System Works includes the latest information on subjects such as vaccines, the immunology of AIDS, and cancer. A highlight of this edition is a new chapter on the intestinal immune system – currently one of the...

The Immune System Recovery Plan: A Doctor's 4-Step Program to Treat Autoimmune Disease

The Immune System Recovery Plan: A Doctor's 4-Step Program to Treat Autoimmune Disease
by Susan Blum (Author), Mark Hyman (Foreword), Michele Bender (Foreword)


One of the most sought-after experts in the field of functional medicine shares her proven four-step program to treat, reverse, and prevent autoimmune conditions and repair your immune system.

• Are you constantly exhausted?

• Do you frequently feel sick?

• Are you hot when others are cold, or cold when everyone else is warm?

• Do you have trouble thinking clearly, aka “brain fog”?

• Do you often feel irritable?

• Are you experiencing hair loss, dry skin, or unexplained weight fluctuation?

• Do your joints ache or swell but you don’t know why?

• Do you have an overall sense of not feeling your best, but it has been going on so long it’s actually normal to you?

IF you answered yes to any...

Super Immunity: The Essential Nutrition Guide for Boosting Your Body's Defenses to Live Longer, Stronger, and Disease Free

Super Immunity: The Essential Nutrition Guide for Boosting Your Body's Defenses to Live Longer, Stronger, and Disease Free
by Joel Fuhrman (Author)


In Super Immunity, world-renowned health expert and New York Times bestselling author of Eat to Live Dr. Joel Fuhrman offers a nutritional guide to help you live longer, stronger, and disease free.Dr. Fuhrman doesn’t believe the secret to staying healthy lies in medical care—rather, the solution is to change the way we eat. With more than 85 plant-based recipes, a two-week menu plan, and lists of super foods that boost immunity, Dr. Fuhrman’s proven strategies combine the latest data from clinical tests, nutritional research, and results from thousands of patients .Fans of Alejandro Junger’s Clean, Mark Hyman’s Ultraprevention, and T. Colin Campbell’s The China Study will appreciate Dr. Fuhrman’s practical plan to prevent and reverse disease—no shots, drugs or sick days...

The Immune System, 4th Edition

The Immune System, 4th Edition
by Peter Parham (Author)


The Immune System, Fourth Edition emphasizes the human immune system and presents immunological concepts in a coherent, concise, and contemporary account of how the immune system works. Written for undergraduate, medical, veterinary, dental, and pharmacy students, it makes generous use of medical examples to illustrate points. This classroom-proven textbook offers clear writing, full-color illustrations, and section and chapter summaries that make the book accessible and easily understandable to students. The Fourth Edition is a major revision that brings the content up-to-date and improves clarity. Based on user feedback, there is now increased continuity and connectivity between chapters. The Immune System is additionally supported by the Garland Science Learning System. This homework...

The Autoimmune Solution: Prevent and Reverse the Full Spectrum of Inflammatory Symptoms and Diseases

The Autoimmune Solution: Prevent and Reverse the Full Spectrum of Inflammatory Symptoms and Diseases
by Amy Myers M.D. (Author)


Over 90 percent of the population suffers from inflammation or an autoimmune disorder. Until now, conventional medicine has said there is no cure. Minor irritations like rashes and runny noses are ignored, while chronic and debilitating diseases like Crohn's and rheumatoid arthritis are handled with a cocktail of toxic treatments that fail to address their root cause. But it doesn't have to be this way.In The Autoimmune Solution, Dr. Amy Myers, a renowned leader in functional medicine, offers her medically proven approach to prevent a wide range of inflammatory-related symptoms and diseases, including allergies, obesity, asthma, cardiovascular disease, fibromyalgia, lupus, IBS, chronic headaches, and Hashimoto's thyroiditis.

Basic Immunology: Functions and Disorders of the Immune System, 5e

Basic Immunology: Functions and Disorders of the Immune System, 5e
by Abul K. Abbas MBBS (Author), Andrew H. H. Lichtman MD PhD (Author), Shiv Pillai MBBS PhD (Author)


In this updated edition of Basic Immunology, the authors continue to deliver a clear, modern introduction to immunology, making this the obvious choice for today's busy students. Their experience as teachers, course directors, and lecturers helps them to distill the core information required to understand this complex field. Through the use of high-quality illustrations, relevant clinical cases, and concise, focused text, it's a perfectly accessible introduction to the workings of the human immune system, with an emphasis on clinical relevance. Concise, clinically focused content is logically organized by mechanism for efficient mastery of the material.Features an appendix of clinical cases and CD molecules.Includes numerous full-color illustrations, useful tables, and chapter outlines....

Immune System: 101 Natural Ways to Boost your Immune System, Fight Germs, and Live a Healthy Life

Immune System: 101 Natural Ways to Boost your Immune System, Fight Germs, and Live a Healthy Life
by Living in Health (Author)


BOOST YOUR IMMUNE SYSTEM! 101 NATURAL WAYS TO BOOST YOUR IMMUNE SYSTEM, FIGHT GERMS, AND LIVE A HEALTHY LIFE Your immune system is the body’s only line of defense against both foreign and internal threats. It is clear therefore that you must maintain your immune system in the best possible condition for optimal health. It is not a myth that some foods are better than others at boosting our immunity. If you were ever wondering what might be the best foods in the world to help keep your immune system in the best shape, then this book is simply the way to go. It really helps to have a great defense mechanism to protect ourselves and it is only logical to have one. If you are still not convinced, then look at the amount of money any country spends on its defense, and compare it to...

The Immune System, 3rd Edition

The Immune System, 3rd Edition
by Peter Parham (Author)


The Immune System, Third Edition emphasizes the human immune system and synthesizes immunological concepts into a comprehensible, up-to-date, and reader-friendly account of how the immune system works.  Written for undergraduate, medical, veterinary, dental, and pharmacy students in immunology courses, it makes generous use of medical examples to illustrate points.  The Third Edition has been extensively revised and updated and includes two new chapters on innate and adaptive immunity, which explore the physical, cellular, and molecular principles underlying these responses to infection.  It also features enhanced coverage of aspects of innate immunity such as the complement system, Toll-like receptors, defensins, and C-reactive protein; the role of dendritic cells in initiating...

How the Immune System Works, Includes Desktop Edition

How the Immune System Works, Includes Desktop Edition
by Lauren M. Sompayrac (Author)


How the Immune System Works is not a comprehensive textbook. It’s the book thousands of students have used to help them understand what’s in their big, thick, immunology texts. In this book, Dr. Sompayrac cuts through the jargon and details to reveal, in simple language, the essence of this complex subject.

Fifteen easy to follow lectures, featuring the uniquely popular humorous style and engaging analogies developed by Dr Sompayrac, provide an introduction to the ‘bigger picture’, followed by practical discussion on how each of the components interacts with one another.  Now featuring full-color diagrams, this book has been rigorously updated for its fourth edition to reflect today’s immunology teaching and includes updated discussion of B and T cell memory, T...

The Gluten Free Guide: How To Lose Weight, Improve Your Skin, and Boost Your Immune System

The Gluten Free Guide: How To Lose Weight, Improve Your Skin, and Boost Your Immune System


Want to make lifestyle change?- Our best selling boxset of healthy living books is available here: http://amzn.to/1s3chEv

The gluten-free diet was first prescribed for people with Celiac disease or who suffered from digestive issues and inflamed intestines. Over the past few years, the diet has grown in popularity as numerous individuals have noticed the benefits of becoming gluten-free. This popularity has recently led to a number of scientific studies and research looking into the effect gluten has on our bodies. This book will be a primer for those looking to cut gluten out of their diet.

© 2016 BrightSurf.com