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


Geisel Researchers Contribute to Study of Trained Immunity
A study published in the journal Science provides support for a new-and still controversial-understanding of the immune system.

Cells from placentas safe for patients with multiple sclerosis
Patients with Multiple Sclerosis (MS) were able to safely tolerate treatment with cells cultured from human placental tissue, according to a study published today in the journal Multiple Sclerosis and Related Disorders.

Nivolumab shows signs of superior response rate compared to standard chemo in advanced melanoma
The monoclonal antibody nivolumab achieves superior response rates and a longer duration of response than standard chemotherapy in patients whose melanoma has progressed after treatment with ipilimumab, according to phase III data presented at the ESMO 2014 Congress in Madrid, Spain.

Studies report new findings on treatment options for mesothelioma
Treating patients with high-dose radiotherapy after chemotherapy and surgery for malignant pleural mesothelioma does not achieve improvements in local relapse and overall survival, according to data from a prospective randomized phase II trial presented at ESMO 2014 Congress in Madrid.

Scientists Identify the Signature of Aging in the Brain
How the brain ages is still largely an open question - in part because this organ is mostly insulated from direct contact with other systems in the body, including the blood and immune systems.

Genetic 'instruction set' for antibodies knocks down hepatitis C in mice
A triple-punch of antibodies both prevented hepatitis C infection and wiped out the disease after it had established itself in laboratory mice, according to a study led by Princeton University researchers.

Spot on against autoimmune diseases and chronic inflammations
Multiple sclerosis, type 1 diabetes and lupus have one thing in common: They are all autoimmune diseases in which the immune cells can no longer differentiate between friend or foe and thus attack the body's own tissue.

Immune activity shortly after surgery holds big clue to recovery rate, Stanford team finds
The millions of people who undergo major surgery each year have no way of knowing how long it will take them to recover from the operation.

Findings give hope to plant extract as possible lupus treatment
New findings by a biomedical engineer and his team at the University of Houston (UH) raise hope for a new class of drugs to treat lupus that may not include the long list of adverse risks and side effects often associated with current treatments for this disease.

A wriggly solution to a first-world problem
Australian researchers have achieved groundbreaking results in a clinical trial using hookworms to reduce the symptoms of celiac disease.
More Immune System Current Events and Immune System News Articles

The Immune System

The Immune System
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...

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 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)


• 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 of these questions, you may have an autoimmune disease, and this book is the “medicine” you need. Among the most prevalent forms of chronic illness in this country, autoimmune disease affects...

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 cell...

The Immune System Cure: Optimize Your Immune System in 30 Days-The Natural Way!

The Immune System Cure: Optimize Your Immune System in 30 Days-The Natural Way!
by Lorna Vanderheaghe (Author)


What causes one person to catch a cold or flu and another to avoid it? Why do serious outbreaks of infectious diseases leave some individuals untouched? What allows someone to be incapacitated by allergies? The answer lies within nature itself-our immune system. The Immune System Cure provides simple techniques for supercharging your immune system to resist and prevent disease. Through diet, exercise, stress reduction and nutritional supplements, including plant sterols and sterolins, you can harness the power of your immune system in just 30 days and help it combat: Antibiotic-resistant bacteria Fibromyalgia Allergies Hepatitis C Tuberculosis Cancer Rheumatoid arthritis and other autoimmune diseases Chronic fatigue syndrome and more Now you can maintain a healthy natural resistance to...

The Immune System

The Immune System
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

The Immune System
by Peter Parham (Author)


The Immune System, Second Edition has been designed for use in immunology courses for undergraduate, medical, dental, and pharmacy students. This class-tested and successful textbook synthesizes the established facts of immunology into a comprehensible, coherent, and up-to-date account of how the immune system works, rather than presenting immunology as a chronology of experiments and discoveries. Emphasizing the human immune system the text has been designed to break down the barriers which often divide basic and clinical immunology. The reader-friendly text, section and chapter summaries, and full-color illustrations make the book accessible and easily understandable to students. The Immune System is adapted from Immunobiology by Janeway, Travers & Walport.

In Defense of Self: How the Immune System Really Works

In Defense of Self: How the Immune System Really Works
by William R. Clark (Author)


We live in a sea of seething microbial predators, an infinity of invisible and invasive microorganisms capable of setting up shop inside us and sending us to an early grave. The only thing keeping them out? The immune system.

William Clark's In Defense of Self offers a refreshingly accessible tour of the immune system, putting in layman's terms essential information that has been for too long the exclusive province of trained specialists. Clark explains how the immune system works by using powerful genetic, chemical, and cellular weapons to protect us from the vast majority of disease-causing microbes-bacteria, viruses, molds, and parasites. Only those microbes our bodies need to help us digest food and process vitamins are admitted. But this same system can endanger us by...

Basic Immunology: Functions and Disorders of the Immune System, 4e

Basic Immunology: Functions and Disorders of the Immune System, 4e
by Abul K. Abbas MBBS (Author), Andrew H. H. Lichtman MD PhD (Author), Shiv Pillai MBBS PhD (Author)


Understand all the essential concepts in immunology with Basic Immunology: Functions and Disorders of the Immune System! This concise, focused text provides you with an up-to-date, accessible introduction to the workings of the human immune system. Efficiently master the immunology information you need through clinically focused content, logically organized by mechanism. Apply what you've learned to real-world situations by referencing the appendix of clinical cases. Enhance your learning with the help of numerous full-color illustrations and useful tables, as well as summary boxes, review questions, and a glossary of immunology terms.Study immunology anywhere! Online access to www.StudentConsult.com opens the door to an enhanced e-book and ancillary components!Visualize complex...

The Ultimate Guide To Immune Disorders: Immune System Treatment For the Weak Immune System (Immune Disorders, Immune Disease Book 1)

The Ultimate Guide To Immune Disorders: Immune System Treatment For the Weak Immune System (Immune Disorders, Immune Disease Book 1)


Take A Weak Immune System And Make It Strong!
Today only, get this Kindle book for just $2.99. Regularly priced at $5.99. Read on your PC, Mac, smart phone, tablet or Kindle device.

Do you get sick frequent and don’t know why? Are you diagnosed with an immune disorder and are looking for good information to help get you on track to better health? This is the book for you! We’ll examine how the immune system works and why you end up with a compromised immune system.

Do you KNOW you have a weak immune system and want to find a way to improve it? Download this book NOW and find out what you may or may not be doing right. Good health sometimes takes a little effort, but this book will help with some easy solutions.

Find out how:
Diet and...

© 2014 BrightSurf.com