Inclusion bodies are
nuclearIn cell biology, the nucleus , also sometimes referred to as the "control center", is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as...
or cytoplasmic aggregates of stainable substances, usually proteins. They typically represent sites of viral multiplication in a bacterium or a eukaryotic cell and usually consist of viral
capsidA capsid is the protein shell of a virus. It consists of several oligomeric structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The capsid encloses the genetic...
proteins. Inclusion bodies can also be hallmarks of genetic diseases, as in the case of Neuronal Inclusion bodies in disorders like
Frontotemporal dementiaFrontotemporal dementia is a clinical syndrome caused by degeneration of the frontal lobe of the brain and may extend back to the temporal lobe...
and
Parkinson's diseaseParkinson's disease is a degenerative disorder of the central nervous system that often impairs the sufferer's motor skills, speech, and other functions....
.
Protein inclusion bodies are classically thought to contain misfolded protein.
Inclusion bodies are
nuclearIn cell biology, the nucleus , also sometimes referred to as the "control center", is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as...
or cytoplasmic aggregates of stainable substances, usually proteins. They typically represent sites of viral multiplication in a bacterium or a eukaryotic cell and usually consist of viral
capsidA capsid is the protein shell of a virus. It consists of several oligomeric structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The capsid encloses the genetic...
proteins. Inclusion bodies can also be hallmarks of genetic diseases, as in the case of Neuronal Inclusion bodies in disorders like
Frontotemporal dementiaFrontotemporal dementia is a clinical syndrome caused by degeneration of the frontal lobe of the brain and may extend back to the temporal lobe...
and
Parkinson's diseaseParkinson's disease is a degenerative disorder of the central nervous system that often impairs the sufferer's motor skills, speech, and other functions....
.
Composition
Protein inclusion bodies are classically thought to contain misfolded protein. However, this has recently been contested, as green fluorescent protein will sometimes fluoresce in inclusion bodies, which indicates some semblance of the native structure and researchers have recovered folded protein from inclusion bodies.
Mechanism of formation
When
genesGênes is the name of a département of the First French Empire in present Italy. It was named after the city Genoa. It was formed in 1805, when Napoleon Bonaparte occupied the Republic of Genoa. Its capital was Genoa. It was divided into the arrondissements of Genoa, Bobbio, Novi Ligure, Tortona and...
from one organism are expressed in another the resulting protein sometimes forms inclusion bodies. This is often true when large evolutionary distances are crossed: a cDNA isolated from Eukarya for example, and expressed as a recombinant gene in a
prokaryoteThe prokaryotes are a group of organisms that lack a cell nucleus , or any other membrane-bound organelles. They differ from the eukaryotes, which have a cell nucleus. Most are unicellular, but a few prokaryotes such as myxobacteria have multicellular stages in their life cycles...
risks the formation of the inactive aggregates of protein known as inclusion bodies. While the cDNA may properly code for a translatable mRNA, the
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
that results will emerge in a foreign microenvironment. This often has fatal effects, especially if the intent of
cloningCloning in biology is the process of producing populations of genetically-identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments , cells , or organisms...
is to produce a biologically active
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
. For example, eukaryotic systems for
carbohydrateCarbohydrates
[Means "hydrates of carbon"] or saccharides
[The word comes from the Greek σάκχαρον, sákcharon, meaning "sugar").] are the most abundant of the four major classes of biomolecules...
modification and
membrane transportIn cellular biology the term membrane transport refers to the collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes namely lipid bilayers that contain proteins embedded in them...
are not found in prokaryotes. The internal microenvironment of a prokaryotic
cellThe cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos...
(
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
, osmolarity) may differ from that of the original source of the
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
. Mechanisms for folding a
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
may also be absent, and hydrophobic residues that normally would remain buried may be exposed and available for interaction with similar exposed sites on other ectopic proteins. Processing systems for the cleavage and removal of internal peptides would also be absent in
bacteriaThe bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
. The initial attempts to clone
insulinInsulin is a hormone that has extensive effects on metabolism and other body functions, such as vascular compliance. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle, and stopping use of fat as an energy...
in a bacterium suffered all of these deficits. In addition, the fine controls that may keep the concentration of a
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
low will also be missing in a prokaryotic cell, and overexpression can result in filling a cell with ectopic protein that, even if it were properly folded, would precipitate by saturating its environment.
Viral inclusion bodies
Examples of viral inclusion bodies in animals are
Intracytoplasmic eosinophilic-
Negri bodiesNegri bodies are eosinophilic, sharply outlined, pathognomonic inclusion bodies found in the cytoplasm of certain nerve cells containing the virus of rabies, especially in Ammon's horn of the hippocampus. Often also found in the cerebellar cortex of postmortem brain samples of rabies victims.They...
in
RabiesRabies is a viral neuroinvasive disease that causes acute encephalitis in warm-blooded animals. It is zoonotic , most commonly by a bite from an infected animal but occasionally by other forms of contact...
Guarnieri bodies in Small pox
Henderson-Peterson bodies in
Molluscum contagiosumMolluscum contagiosum is a viral infection of the skin or occasionally of the mucous membranes. MC has no animal reservoir, infecting only humans, as did smallpox. However, there are different pox viruses that infect many other mammals. The infecting human MC virus is a DNA poxvirus called the...
Intranuclear acidophilic-
Cowdry type A in
Herpes simplex virusHerpes simplex virus 1 and 2 are two species of the herpes virus family, Herpesviridae, which cause infections in humans...
and
Varicella zoster virusVaricella zoster virus is one of eight herpes viruses known to infect humans . It commonly causes chicken-pox in children and both shingles and postherpetic neuralgia in adults.-Nomenclature:...
Cowdry type B in Polio
Torres bodies in
Yellow feverYellow fever is an acute viral disease. The virus, a 40 to 50 nm enveloped RNA virus of the family of Flaviviridae is transmitted by the bite of mosquitoes...
Intranuclear basophilic-
Cowdry type B in Adenovirus
Both intranuclear and intracytoplasmic-
Warthin finkeldey bodies in
MeaslesMeasles is an infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus. Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses...
Examples of viral inclusion bodies in plants
http://plantpath.ifas.ufl.edu/pdc/Inclusionpage/Florvirus.html include aggregations of virus particles (like those for
Cucumber mosaic virus http://plantpath.ifas.ufl.edu/pdc/Inclusionpage/CMV/CucMoInc.html) and aggregations of viral proteins (like the cylindrical inclusions of potyviruses
http://plantpath.ifas.ufl.edu/pdc/Inclusionpage/Poty/poty.html). Depending on the plant and the plant virus family these inclusions can be found in epidermal cells, mesophyll cells, and stomatal cells when plant tissue when properly stained
http://plantpath.ifas.ufl.edu/pdc/Inclusionpage/Howto.html.
Inclusion bodies in Erythrocytes
Normally a
red blood cellRed blood cells are the most common type of blood cell and the vertebrate body's principal means of delivering oxygen to the body tissues via the blood. They take up oxygen in the lungs or gills and release it while squeezing through the body's capillaries. The cells are filled with hemoglobin, a...
does not contain inclusions in the cytoplasm. However, it may be seen because of certain hematologic disorders.
There are three kinds of erythrocyte inclusions:
- Developmental Organelles
- Howell-Jolly bodies: small, round fragments of the nucleus resulting from karyorrhexis
Karyorrhexis is the destructive fragmentation of the nucleus of a dying cell whereby its chromatin is distributed irregularly throughout the cytoplasm. It is usually preceded by pyknosis and is followed by karyolysis and can occur either as a result of programmed cell death or necrosis....
or nuclear disintegration of the late reticulocyteReticulocytes are immature red blood cells, typically composing about 1% of the red cells in the human body.Reticulocytes develop and mature in the red bone marrow and then circulate for about a day in the blood stream before developing into mature red blood cells. Like mature red blood cells,...
and stain reddish-blue with Wright stain.
- Basophilic stipplings - this stipplings is either fine or coarse, deep blue to purple staining inclusion that appears in erythrocytes on a dried Wright stain.
- Pappenheimer bodies
Pappenheimer bodies are abnormal granules of iron found inside red blood cells on routine blood stain.They are a type of inclusion body formed by phagosomes that have engulfed excessive amounts of iron. They are seen in diseases such as sideroblastic anemia, hemolytic anemia, and sickle cell disease...
- are sideroticSiderosis is the deposition of iron in tissue.When used without qualification, it usually refers to an environmental disease of the lung.Also Siderosis Bulbi, deposition of iron into the eye causing injury as the material chemically reacts with tissues and cells.-Causative agent:Iron oxide present...
granules which are small, irregular, dark-staining granules that appear near the periphery of a young erythrocyte in a Wright stain.
- Polychromatophilic red cells - young red cells that no longer have nucleus but still contain some RNA.
- Cabot Rings
Cabot rings are thin, red-violet staining, threadlike strands in the shape of a loop or figure-8 that are found on rare occasions in erythrocytes...
- ring-like structure and may appear in erythrocytes in megaloblastic anemiaMegaloblastic anemia is an anemia that results from inhibition of DNA synthesis in red blood cell production. This is often due to deficiency of vitamin B and/or folic acid...
or in severe anemias, lead poisoningLead poisoning is a medical condition caused by increased levels of the heavy metal lead in the body...
, and in dyserythropoiesis, in which erythrocytes are destroyed before being released from the bone marrowBone marrow is the flexible tissue found in the hollow interior of bones. In adults, marrow in large bones produces new blood cells. It constitutes 4% of total body weight, i.e...
.
- Abnormal Hemoglobin Precipitation
- Heinz bodies - round bodies, refractile inclusions not visible on a Wright stain film. It is best identified by supravital staining with basic dyes.
- Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
H Inclusions - alpha thalassemiaThalassemia is an inherited autosomal co-dominant blood disease. In thalassemia, the genetic defect results in reduced rate of synthesis of one of the globin chains that make up hemoglobin...
, greenish-blue inclusion bodies appear in many erythrocytes after four drops of blood is incubated with 0.5mL of Brilliant cresyl blue for 20 minutes at 37°C.
- Protozoan Inclusion
- Malaria
Malaria is a vector-borne infectious disease caused by a eukaryotic protist of the genus Plasmodium. It is widespread in tropical and subtropical regions, including parts of the Americas, Asia, and Africa. Each year, there are approximately 350–500 million cases of malaria, killing between one and...
- Babesia
Babesia is a protozoan parasite of the blood that causes a hemolytic disease known as Babesiosis. There are over 100 species of Babesia identified; however only a handful have been documented as pathogenic in humans....
Current problems with the isolation of proteins from bacterial inclusion bodies
70-80% of the expressed proteins in E. Coli by recombinant techniques are contained in inclusion bodies (i.e., protein aggregates).The purification of the expressed proteins from inclusion bodies usually require two main steps, Extraction of inclusion bodies from the bacteria followed by the solubilisation of the purified inclusion bodies. This is considered labour-intensive, time consuming and not cost effective.
Inclusion bodies purification Technology
http://norgenbiotek.com/index.php?id=protkincl uses a proprietary cell lysis reagent to selectively lyse the cells and release inclusion bodies in their solid form. Using the IB Solubilization Reagent, inclusion bodies are dissolved and their contents released. Inclusion body proteins are then further purified by loading onto spin columns containing SiC. Non-specifically bound components in the solution can be washed from the column, leaving the inclusion body protein bound to the SiC. These specific proteins can then be recovered using the elution buffer.