immunology

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Proteus OX19 and the Polish Schindler,

Proteus OX19 is a strain of the bacterium Proteus vulgaris, a simple gram negative bacteria that is commonly found in dirt and water.  It is a fairly unremarkable bacteria, some exposed to it might suffer urinary tract infections or infections of wounds.  However, most infected with the bacteria will suffer few symptoms as the body’s immune system eradicates the invading microbe.  It does have one interesting reaction, however.  People exposed to Proteus OX19 often test false positive for typhus, a disease which is much deadlier and can cause terrible outbreaks and epidemics.

When Germany invaded Poland on Sept. 1st, 1939, Dr. Eugeniusz Lazowski served as an army doctor with the Polish Army.  After the occupation of Poland by Germany, Dr. Lazowski returned home to Rozwadow to continue his private medical practice.  However, he heard news of mass deportations of Poles and Jews by the Nazi’s.  Hundreds of thousands of Jews were being rounded up and deported to concentration camps.  Hundreds of thousands of Poles were also being deported to Germany as forced labor.  It was only a matter of time before the Germans demanded the deportation of Poles from Rozwadow, and Lazowski was determined that the Nazi’s would go empty handed.

Lazowski solution was ingenious and audacious; to keep the Germans away from Rozwadow by simulating a fake typhus epidemic. At the time, Germany was terrified of the prospect of a typhus outbreak spreading across the Fatherland, and strict protocols were in place to isolate and quarantine infected areas.  Inspired by the Proteus microbe, Lazowski informed German medical officials that Rozwadow was being ravaged by a terrible typhus epidemic.  With the help of his friend, Dr Stanisław Matulewicz, Dr. Lazowski injected the people of Rozwadow with proteus OX19, as well as the residents of several nearby Jewish ghettos, so that they would all test false positive for typhus.  He then sent blood samples to German medical officials.  As predicted, the samples all tested false positive for typhus.

In response, the Germans sent three medical inspectors to assess the seriousness of the epidemic.  The three inspectors were greeted cordially and plied with food and generous amounts of vodka.  They were then given a short tour of the town.  Due to fears of contracting the disease, the Germans only made a cursory examination of the town.  Then they were led to a fake medical ward filled with severely ill patients.  Dr. Lazowski claimed they were suffering from typhus, and again due to the German’s fear of contracting the disease, they made no medical assessments.  Instead they took Dr. Lazowski at his word and sped out of Razwadow, declaring the town and surrounding area to be in a state of quarantine.  Little did they know, the so called “patients” the German’s were led to were people with flu and pneumonia, told to act as sick as possible.

Due to the quarantine, the Germans never deported anyone from Razwadow or the ghettos.  As a result, he is credited with saving 8,000 Jews from certain death, and thousands of other Poles from deportation.  Throughout the rest of the war he lent his medical services to the Polish resistance, and worked to smuggle Jews to safety from the Nazi’s.  After the war he moved to the United States and worked as a pediatrician.  He died in 2006 at the age of 96.

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Here’s some stunning video of your immune cells doing their thing. 

Every so often, your body’s own cells become dangerous to you. When that happens, cytotoxic T cells (also known as T killer cells) are your immune system’s way of dealing with the threat. 

More often than not, they succeed in vanquishing cells that have become infected with viruses or mutated to the point of becoming cancerous before they can cause further trouble. 

To accomplish this, they’re armed with a battery of chemical weapons and enzymes that they can use to cause target cells to burst open in the event known as lysis. 

Examine the image captions for some more information on what you’re looking at in each one. 

I produced these gifs from some of the latest microscope footage to come out of the National Institutes of Health. Check out the source of this post for some more detailed information and video. It’s pretty amazing how small these things are; ten of them could fit end-to-end across the tip of a human hair. 

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Overview of the Immune System

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Why You Are Still Alive - The Immune System Explained by Kurzgesagt.

Bill Gates is commissioning art to remind people why vaccines are important

At first glance, the image above looks like it comes from a spread in Vogue magazine. Shot by Australian photographer Alexia Sinclair, it certainly has all the elements of a high-gloss fashion magazine photo shoot: gorgeous styling, moody lighting, a beautiful model, something odd going on in the background.

It is in the background, however, that the purpose of the image reveals itself. Off to the side, that’s Dr. Edward Jenner inoculating James Phipps, the first person to receive the smallpox vaccine, in 1796. Less than 200 years later, in 1980, the World Health Organisation declared that smallpox was eradicated. (The woman in the foreground of the photograph alludes to the indiscriminate nature with which disease infects rich and poor alike.)

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The human leukocyte antigen (HLA) system is the locus of genes that encode for proteins on the surface of cells that are responsible for regulation of the immune system in humans. This group of genes resides on chromosome 6, and encodes cell-surface antigen-presenting proteins and has many other functions.

The HLA genes are the human versions of the major histocompatibility complex (MHC) genes that are found in most vertebrates (and thus are the most studied of the MHC genes). The proteins encoded by certain genes are also known as antigens, as a result of their historic discovery as factors in organ transplants. The major HLAs are essential elements for immune function. Different classes have different functions:

  • HLAs corresponding to MHC class I (A, B, and C) present peptides from inside the cell. For example, if the cell is infected by a virus, the HLA system brings fragments of the virus to the surface of the cell so that the cell can be destroyed by the immune system. These peptides are produced from digested proteins that are broken down in the proteasomes. In general, these particular peptides are small polymers, about 9 amino acids in length.[citation needed] Foreign antigens presented by MHC class I attract killer T-cells (also called CD8 positive- or cytotoxic T-cells) that destroy cells.
  • HLAs corresponding to MHC class II (DP, DM, DOA, DOB, DQ, and DR) present antigens from outside of the cell to T-lymphocytes. These particular antigens stimulate the multiplication of T-helper cells, which in turn stimulate antibody-producing B-cells to produce antibodies to that specific antigen. Self-antigens are suppressed by regulatory T cells.
  • HLAs corresponding to MHC class III encode components of the complement system.

HLAs have other roles. They are important in disease defense. They are the major cause of organ transplant rejections. They may protect against or fail to protect (if down-regulated by an infection) against cancers. Mutations in HLA may be linked to autoimmune disease (examples: type I diabetes, coeliac disease). HLA may also be related to people’s perception of the odor of other people, and may be involved in mate selection, as at least one study found a lower-than-expected rate of HLA similarity between spouses in an isolated community.

Aside from the genes encoding the 6 major antigen-presenting proteins, there are a large number of other genes, many involved in immune function, located on the HLA complex. Diversity of HLAs in the human population is one aspect of disease defense, and, as a result, the chance of two unrelated individuals with identical HLA molecules on all loci is very low. HLA genes have historically been identified as a result of the ability to successfully transplant organs between HLA-similar individuals.

Molecules seen binding to HIV-1’s protective capsule, blocking infection

Imagine a suitcase on a bumpy ride. With enough jostling it opens, spilling clothes everywhere. Similarly awkward, the suitcase locks may jam and not open at the destination.

This analogy illustrates the importance of the protective capsule, called the capsid, which surrounds the HIV-1 genome. (HIV is short for human immunodeficiency virus.) The capsid has to disassemble once the virus enters the cell, releasing its disease-causing cargo at precisely the right time and place.

“It’s still a matter of debate at what point the capsid falls apart in HIV-1 infection of cells,” said Dmitri Ivanov, Ph.D., assistant professor of biochemistry in the School of Medicine at The University of Texas Health Science Center at San Antonio. Dr. Ivanov is a senior author on a study, published in Proceedings of the National Academy of Sciences, that offers clues about HIV-1 capsid disassembly.

The paper shows how an HIV-1 inhibitor called PF74 and a host protein called CPSF6 bind to a small pocket on the surface of the capsid and prevent it from disassembling. The suitcase, if you will, is locked. Viral information is kept inside.

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Made With Paper

This is not a kidney, but a lymph node, where B cells differentiate into antibody-secreting plasma cells and memory cells which play a big role in our body’s humoral immune response. In the humoral immune response, B cells secrete antibodies which neutralise pathogens (esp. viruses) and prevent them from binding to host cells during a prolonged infection. 

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TOP:  Anatomy of a Bacteriophage
MIDDLE:  A Bacteriophage Attacking a Bacterium
BOTTOM:  What a Phage Does to its Host

The cycle begins when the virus uses its tail fibers to attach itself to its victim. The details of what happens next vary, but the process is always the same: the phage’s genetic material, which is located in its head, enters the bacterium.

Here, we’ll use T4, a well-studied phage infecting the Escherica coli bacterium, as an example.

(1) T4 contracts its tail sheath which pushes a tube located within the tail through the membrane of the bacterial cell.

(2) The phage’s DNA is passed through the tube into the cell, where it takes control, brutally stops many of its vital functions and forces it to churn out new virus components – heads, tails, tail fibers – in production-line style.

(3). Finally, enzymes dissolve the wall of the bacterium from the inside and the newborn bacteriophages reach the exterior, ready to attack new victims.

(4)  But these viruses proceed very selectively as they do so. Most of them attack only a subgroup of a single bacterial species. Generally, they don’t touch animal or human cells, which is why they are harmless to human beings.

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