Virology question of the week

9 April 2014

HIV binding CD4 and ccrOn the science show This Week in Virology we receive many questions and comments, which are read every week. I also get many questions here on virology blog, which I tend to answer by email. However I think that everyone could benefit from these questions, so I’ve decided to post one here each week along with my answer.

This week’s question is from Joseph, who wrote:

I’m relatively new to virology or anything biology-related. Hell, I’m studying computer science as an undergrad at the moment; however, there’s something about virology that fascinates me – the simplistic fact that we can’t cure viruses, which are less complex than bacterium (in which we can treat, and they’ll eventually pack their bags and leave).

I’ll get to my question … since most, if not all, cells in the body replicate and reproduce and none of them merge, why do our cells let virions in? You would think after years of viral/immune system encounters, our bodies would have adapted to repelling these viruses off. I understand it’s probably much more complicated than that, but I would love to hear your answer. Does it have anything to do with virions’ size being so small?

This is a great question. In fact, I had a similar question on a midterm examination in my virology course. I phrased it this way: Could cells evolve to not have receptors for binding viruses?

I sent this answer to Joseph:

Viruses get into cells by binding to proteins on the cell surface – viruses have evolved to do this: they are safecrackers.

You would think that the cells would evolve to change these proteins – and you would be right. Over thousands of years, the cell proteins change, so the viruses can’t bind anymore.

But guess what? The viruses change right back so that they can bind to the cell protein once more.

Now you might ask: why doesn’t the cell get rid of that surface protein? The answer there is that they are needed for the cell, so they can’t be removed.

There seems to be one exception to the last statement: about 4-16% of people of Northern European descent don’t make one of the receptors for HIV. They are resistant to infection. But this doesn’t happen for most other viruses.

Joseph wrote back:

Hmm. I thought by definition virions weren’t living organisms, yet they “adapt” to bind to living cells. Sounds like those emotional virions just can’t deal with rejection – that and our cells just aren’t as smart as we need them to be. I’m not sure if you are a Trekkie; however, it reminds me of the Borg and The Enterprise’s encounter – The Enterprise adapting to The Borg’s every frequency of their phasers, bypassing their bruteforce.

That does make sense that our cells do need that protein surface for energy; however, I never thought it would actually be the surface itself. Interesting.

I did read about that somewhere – because of the Bubonic Plague causing some genetic mutation, if I’m not mistaken.

To which I responded:

Virus particles are not alive – but once they infect a living cell they can evolve.

Both cells and viruses are smart – they both have managed to be around for a long time. We have great immune systems; virus infected cells can evolve very quickly. It’s an arms race.

Correct, one idea is that the mutation conferring resistance to HIV was acquired in the Plague, but that’s hard to prove.

The mutation we are discussing is of course ccr5delta32, which confers resistance to infection with HIV-1 (the illustration shows the HIV-1 glycoprotein binding CD4 and ccr, a chemokine receptor). You can read more about ccr5delta32 here or listen to us discuss it on TWiV #278. We also talked about virus-receptor arms races on TWiV #242, and I wrote about it here.

  • Vince

    An interesting point also is that in many branches of life, certain viruses offer benefits to their hosts. Organisms use them for genetic exchanges, adaptation to previously uninhabitable environments, and in humans, placental fusion and recently observed, regulation of the capacity for stem cells to morph into one cell type or another.
    So, perhaps this is just an outcome of the success of viral infections, or, perhaps there is a selective advantage conferred by these genetic parasites?

  • gsgs

    at least the virus shouldn’t be so virulent ! No benefit.
    Virulence is an accident of evolution. (or host switch)

  • Dorian McILROY

    Another thing I thought of when I read this part of the question,

    “cells in the body replicate and reproduce and none of them merge, why do our cells let virions in”

    is that you might wonder why, even if cells can’t get rid of every virus receptor protein, they can’t modify their membranes so that enveloped viruses can’t deliver their contents into the cell.

    I guess the answer lies in the fact that cell membranes need to be flexible. Membrane bound compartments inside the cell communicate by exchanging vesicles, which bud off from a membrane in one part of the cell, then deliver their cargo at their destination by fusing with the membrane at the destination. So, even if cells do not (generally) merge with each other, inside every cell, there is a whole lot of membrane merging going on 24/7. This ability of cell membranes to merge under specific conditions is essential – membranes that are so rigid that viruses could not get into the cell would not be compatible with cell survival.

  • apostleshadamishe

    AMBUSH CURES HIV/AIDS

    Apostle Shada Mishe

    apostleshadamishe@gmail.com

    Sir / Madam,

    For the past 12 years I have been studying and researching Ambush, a Palm plant extract that is effective in curing HIV.

    Name of Plant; Palm

    Name of ingredient: Ambush

    Molecular weight 640 (similar to the sequisulfides)

    Where found: In and around the areas of South Florida where uranium waste was dumped in the 1920’s from the nuclear programme that has now leaked out into the water system. A specie of the PALM plant has picked up this waste to be the valuable AMBUSH.

    Chemical compd; Uranium isotope (cus.n) Grayish white soft metallic compound NOT found in chemistry books.

    Uses: Antiviral DRUG..Ambush

    Found to “KILL” the HIV virus when given in a dose of 60 ml three times daily for 21 days at a known concentration.

    Mode of action.. Ambush kills the HIV virus by causing the viral shell to rupture . In the lymph system Ambush produces “natural radioactivity” that “kills” the virus that ‘hides’ in the lymph system . This crosses the blood-brain barrier since the ‘patients’ claim that they are able to see,hear and think more clearly after taking Ambush.

    Viral Loads…This decreases from 100,000 to ‘undetectable’ in 21 days….. but I have had patients VL go to ‘undetectable ‘ in 5 days.

    SIDE EFFECTS / EFFECTS
    1. After 5 to 7 days of treatment, patients MAY complain of HEADACHES.
    2. After 5 to 7 days male patients experience an increase in erection.
    3. Stool becomes soft and REGULAR
    4. Patients c/o being WARM in the trunk area mainly at night when lying down.

    Toxicology……Before administering to any person a complete toxicological analysis was done to include, arsenic, barbiturates and NO KNOWN poisons or harmful substances to mankind were found.

    Systems/Organs

    Skin…becomes clean, smooth and free of eczema or other say they have small eczema patches in the first week that go away by the third week.

    Excretion
    Since this is a very LARGE molecule it is excreted relatively unchanged via urine and feces.

    SEROREVERSION
    After 149 days the patents revert to being HIV NEGATIVE after finishing a course in Ambush hence no one goes public to say they WERE HIV positive.

    Pharmacology of Ambush on the GUT of an end stage AIDS person.

    It is known that late stage AIDS patients posses a high level of the virus in the GUT which should include the entire GI tract from stomach to rectum. Here the virus is found in the lining and this is difficult for ARV’s because these are the areas needed by the ARV’s to enter the blood supply. There is not a high enough blood level returning back to the stomach lining hence the virus remains in high concentration.

    This causes the person’s appetite to decrease which causes a spiraling downhill of the body.

    When Ambush is taken in the liquid form, it is slightly basic and forms a stable compound in the acidic stomach.The Ambush compound is close to the stomach lining to exert the “natural radioactivity” effect which kills the virus in the stomach. Here the entire mid section feels very warm and sometimes feverish. The infected stomach lining with the dead areas is then passed out as a black slime in the stool. This usually happens about day 4 while on an Ambush regime of 60 ml three times daily for 21 days, wherein the person has a large bowel movement.

    After the bowel movement, the person becomes extremely hungry and eats TWO to THREE times a normal serving. Here I usually recommend cornmeal porridge with butter or cooking oil as a prevention against malnutrition and add a daily multivitamin. By day 10 the stomach has recovered and the person eats normally.

    THE CHALLENGE

    The challenge is to find a Virologist, or Biologist of HIV Researcher who is willing to put some Ambush in a Human culture medium infected with the HIV virus, incubate with proper controls and report their findings to the world.

    More info is at http://www.ambushcuresaidsfree.com or
    http://www.youtube.com/user/apostlemishe?feature=mhee

    Thank you for your interest and we will be happy to send you samples and answer any and all questions.

    Apostle Shada Mishe
    apostleshadamishe@gmail.com
    Dallas Texas,
    1-972 294 5161

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