Science Current Events | Science News |

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

Genetic variation is key to fighting viruses
Using a genome-wide association study, EPFL scientists have identified subtle genetic changes that can cause substantial differences to how we fight viral infections.

New study shows electronic tracking helps reduce blood transfusions & infection rates
An electronic system developed and implemented by Intermountain Healthcare that monitors how physicians give blood to patients after a surgical operation has enabled the healthcare system to significantly reduce the amount of blood transfusions patients receive, cutting costs by $2.5 million over two years and contributing to lower infection rates without harming patients, according to a new study presented Wednesday at the 2015 Clinical Congress of the American College of Surgeons.

Department of Defense awards nearly $6 million grant to further bone fracture repair research
A collaborative research team led by scientists at Houston Methodist is one step closer to developing technologies that could help mend broken bones faster.

Fresh insight into rheumatoid arthritis offers hope for transforming patient care
Scientists have discovered what they believe has the potential to prevent the onset of an aggressive and hard-to-treat form of rheumatoid arthritis - a condition that affects 700,000 adults in the UK.

Sugar governs how antibodies work in the immune system
The immune system is our biological defense shield. Antibodies protect the organism against invading pathogens such as viruses or bacteria.

Tolerant immune system increases cancer risk
For a malignant tumor to form, cancer cells must evade the immune system's attack. Numerous studies have already shown that cancer spreads particularly aggressively if there is an unfavorable balance between suppressing and active immune cells in the tumor microenvironment.

Treatment for heparin-induced blood disorder revealed in structure of antibody complex
A potential treatment for a serious clotting condition that can strike patients who receive heparin to treat or prevent blood clots may lie within reach by elucidating the structure of the protein complex at its root, according to new research from the Perelman School of Medicine at the University of Pennsylvania.

Indiana University study: Sexual activity causes immune system changes that increase chances of conception
Research from Indiana University has found that sexual activity triggers physiological changes in the body that increase a woman's chances of getting pregnant, even outside the window of ovulation.

Rescuing intestinal stem cells from attack in type 1 diabetes
Up to 80 percent of people with long-standing type 1 diabetes develop gastrointestinal symptoms--abdominal pain, bloating, nausea, vomiting, diarrhea, constipation and fecal incontinence--that severely diminish quality of life.

Cell marker enables prognosis about the course of infections
When a pathogen invades the body, specific cells in the human immune system are ready to take immediate action in order to destroy it.
More Immune System Current Events and Immune System News Articles

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...

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, 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 cell activation, vaccines,...

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...

Immune System: The Ultimate Immune System Guide - How To Build An Unbreakable Natural Immune System (Autoimmune, Pain Management, Diet Therapy, Anti Inflammatory, ... Clean Eating, Healthy Habits, Healing)

Immune System: The Ultimate Immune System Guide - How To Build An Unbreakable Natural Immune System (Autoimmune, Pain Management, Diet Therapy, Anti Inflammatory, ... Clean Eating, Healthy Habits, Healing)

Boost Your Immune System Immediately!
Are You Often Getting Sick?

Millions of people are always ill through bad habits and poor choices. Many people realize how they should feel and act, yet are unable to break away from their ingrained routine. They often feel as if they are in a constant battle with sickness, not only does this affect their body in it's ability to function to it's best capacity but often spills over into others areas of their lives. Your immune system is your greatest line of defense against disease, without a strong immune system you are opening yourself up to an entire list of debilitating illness.

Create An Unstoppable Immune System!

If you are suffering from constant battles with disease and infection, it's that you don't...

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 opens the door to an enhanced e-book and ancillary components!Visualize complex...

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...

Immune System Makeover: Enjoy better health

Immune System Makeover: Enjoy better health
by Janet Maccaro PhD CNC (Author)

If you're tired of being sick and tired, and if you're ready for a complete immune system makeover, this powerful, easy-to-follow 90-day immune system makeover can show you how. Mark your calendar!You can build and strengthen your immune system, bring your body's systems into proper balance and experience disease-free living!No matter how your health has been in the past, there is something you can do right now to give your health a complete makeover---to give you the vitality and energy to embrace life at your best!This amazing guide to renewed health gives you:News vital to improving your daily life---which foods heal, which vitamins and supplements build and restore your health Amazing facts--how your immune system is your miraculous internal pharmacy Valuable self-tests that help you...

How the Immune System Works (Blackwell's How It Works)

How the Immune System Works (Blackwell's How It Works)
by Lauren M. Sompayrac (Author)

Understanding the immune system is crucial for both medical and bioscience students, with new research revealing yet more secrets year on year. Many books offer in-depth introductions to the subject, but How the Immune System Works remains uniquely popular for its personable and practical overview of the nuts and bolts of the immune system. This third edition provides a perfect introduction to the essential principles of the immune system, covered in humorous but highly informative 'lectures' accompanied by clear and accessible illustrations. It is perfect for exam preparation or as an enjoyable overview of a difficult subject. Both students and instructors will welcome the clarity and authority that Lauren Sompayrac brings to this timely revision.

© 2015