Arkiv för HERPES Kategorin

This is not a joke. Yesterday I image-googled herpes simplex and this is what I got.

Gives me another perspective of what it is I am spending my time with actually.

An ongoing current study, very interesting I find it. My goal now was to be able to write at least a couple of sentences about this before I go to bed.

Recurrent HSV-2 meningitis patients have increased HSV-specific adaptive and innate immune responses, raising the possibility of immune-mediated pathology in the development of recurrent HSV2 meningitis.

I think I will continue tomorrow.

this cute doggy is about to jump in

will be continued…

Retrieved from reference article:

http://www.ncbi.nlm.nih.gov/pubmed/19136636

PRETTY COOL I THINK

Fig. 1. Electron microscopy and 3D reconstruction of C3b and C3bB(Ni2). (A) Reference-free 2D averages obtained for the data set containing images of single molecules of C3b. These averages reveal a characteristic ‘‘L’’ shape evocative of the C3b crystal structure. (B) Reference-free 2D averages of C3bB(Ni2) display a bulky appearance compatible with fB binding to C3b. (C) Front view of the 3D structure of C3b derived from the EM data at a resolution of 28 Å (gray density). The atomic structure of C3b (PDB file 2i07) has been fitted within the EM map and displayed in purple with the C345C and CUB domains highlighted in orange and blue, respectively. (D) Several views of the 3D structure of C3bB(Ni2) at 27 Å resolution (gray density). Fitting of the atomic structure of C3b (PDB file 2i07) allows the assignment of specific regions of the EM map to specific C3b domains. Some densities of the 3D reconstruction cannot be accounted by C3b (asterisks) and correspond to C3b-bound fB.

What does the complement cascade look like really?

In humans, herpes simplex virus type 2 (HSV-2) represents one of the most prevalent sexually transmitted diseases in the world (Duerst et al). Herpesvirus have been found in the black-footed penguin as well, like the penguins found kissing in Slottsskogen this Saturday.

Primary infection of HSV develops into the establishment of latency in the central nervous system (CNS) where it silently rests during the life of the host.

Katarina’s Refleciones Laboratores type 3

The route of HSV infection is characterized by retrograde transport from the site of inoculation to local sensory ganglia followed by infection throughout the body via anterograde transport in neurons to peripheral nerve endings.

Once the virus has entered the ganglia, it travels to spinal cord and from there to the skin, where it causes lesions or sores (Stanberry, lawrence R.; Thapa et al).

Factors such as hormonal changes, stress or immune suppression can cause mild or severe reactivation identified by periodical sheding in genital secretions, however most HSV-2 infections are asymptomatic. Virus that enters the lab should NOT be thrown into the sink, but instead in special boxes marked (yellow) for proper destruction.

Chemokines as immunotransmitters?

Alain Trautmann

Figure 1. The chemokine receptor CCR5 is recruited at a T cell−B cell synapse (1) and this recruitment probably requires chemokine secretion by the APC¹.
This CCR5 recruitment may help explain why conjugated T cells resist ‘distracting’ chemokines better than free T cells (2).
Additional explanations for the chemokine-dependent stability of T cell−B cell conjugates should be considered. For example, chemokines binding to their synaptic receptors may provide direct costimulation for T cell activation (3),
and chemokines as well as TCRs might contribute to the increase in the avidity of integrins for their ligands (4).
Here, the chemokines and receptors are those found at synapses between EBV−B cells and Jurkat T cells. For dendritic cells and naive T cells, similar effects could be exerted by actions of CCL19 on CCR7. MHC, major histocompatibility complex.

Katie Ris

Chemotactic cytokines
Chemokines are classified into polypeptide groups identified by the location of cysteine residues near their amino termini (for example, C-C, C-X-C, C and CX3C).
Chemokines represent the largest family of cytokines (~41 human members), forming a complex network for the chemotactic activation of all leukocytes.
Chemokine receptors, members of the seven-transmembrane-spanning G-protein-coupled receptors, vary by cell type and degree of cell activation.
There is considerable redundancy in chemokine-receptor interaction, as many ligands bind different receptors, or vice versa.
The composition of chemokines produced at sites of tissue wounding not only recruits downstream effector cells (as discussed above), but also dictates the natural evolution of immune reactivity.
For example, MCP-1/CCL2, a potent chemotactic protein for monocytes and lymphocytes, simultaneously induces expression of lymphocyte-derived IL-4 in response to antigen challenge while decreasing expression of IL-12.
The net effect of this alteration facilitates a switch from a TH1-type to a TH2-type inflammatory response.

The chemokine connection
Chemokines were initially defined functionally as soluble factors regulating directional migration of leukocytes during states of inflammation; however, chemokine biology extends to all cell types, including most human neoplastic cells.
Regulation of tumour growth by chemokines—Some tumour cells not only regulate their chemokine expression to help recruit inflammatory cells, but also use these factors to further the tumour growth and progression.

Regulation of angiogenesis by chemokines—
Although angiogenesis is strictly controlled, it is associated with chronic inflammatory diseases, such as psoriasis, rheumatoid arthritis and fibrosis, as well as with tumour growth and metastasis. It is well established that CXC chemokines with the three amino acids (Glu-Leu-Arg/ELR) immediately amino-terminal to the CXC motif (ELR+) are pro-angiogenic and stimulate endothelial cell chemotaxis, whereas ELR− CXC chemokines (for example, PF-4/CXCL4, MIG/CXCL9 and IP-10/CXCL10) possess angiostatic activities.
ELR+ CXC ligands bind to CXCR2 and to a lesser degree to CXCR1, whereas ELR− CXC ligands bind to CXCR3, CXCR4 and CXCR5.

Chemokines and metastasis—
Malignant cells that possess metastatic capacity have properties endowing them with the ability to invade and survive in ectopic tissue, venous and/ or lymphatic environments, as well as ability to reside and proliferate at a distal site (Fig. 3).
Much debate exists as to whether malignant cells metastasize to environments favouring their specific growth or whether different organs are endowed with the ability to arrest or attract specific types of malignant cells through chemotactic factors (the so-called homing theory) 48.
Studies using a mouse model by Muller and colleagues suggest that the pattern of breast cancer metastases is in part governed by specific interactions between CXCR4 and its ligand SDF-1/CXCL12.
CXCL12 is a rather unique chemokine in that it is the product of resting cells in multiple organs, and is particularly highly expressed in target organs for breast cancer metastasis.
CXCL12 triggers chemotaxis of malignant mammary carcinoma cells in vitro, and the chemotactic activity of extracts of organs targeted by breast cancer cells (bone marrow, liver, lung and lymph nodes) can be neutralized by anti-CXCR4 antibodies.
The involvement of CXCR4 in metastasis is not limited to breast cancer, as CXCR4 is expressed in tumour cell lines (for example, prostate carcinomas, B-cell lymphomas, astrogliomas and chronic lymphocytic leukaemias) that also respond to CXCL12.
The broader implications of these observations are that chemokines may be involved in regulating the spectrum of metastases in diverse cancer types.

Wound healing versus invasive tumour growth.  
a, Normal tissues have a highly organized and segregated architecture. Upon wounding or tissue assault, platelets are activated and form a haemostatic plug where they release vasoactive mediators that regulate vascular permeability, influx of serum fibrinogen, and formation of the fibrin clot. Chemotactic factors such as transforming growth factor-β and platelet-derived growth factor, derived from activated platelets, initiate granulation tissue formation, activation of fibroblasts, and induction and activation of proteolytic enzymes necessary for remodelling of the extracellular matrix (for example, matrix metalloproteinases and urokinase-type plasminogen activator). In combination, granulocytes, monocytes and fibroblasts are recruited, the venous network restored, and re-epithelialization across the wound occurs. Epithelial and stromal cell types engage in a reciprocal signalling dialogue to facilitate healing. Once the wound is healed, the reciprocal signalling subsides. 
 b, Invasive carcinomas are less organized. Neoplasia-associated angiogenesis and lymphangiogenesis produces a chaotic vascular organization of blood vessels and lymphatics where neoplastic cells interact with other cell types (mesenchymal, haematopoietic and lymphoid) and a remodelled extracellular matrix. Although the vascular network is not disrupted in the same way during neoplastic progression as it is during wounding, many reciprocal interactions occur in parallel. Neoplastic cells produce an array of cytokines and chemokines that are mitogenic and/or chemoattractants for granulocytes, mast cells, monocytes/macrophages, fibroblasts and endothelial cells. In addition, activated fibroblasts and infiltrating inflammatory cells secrete proteolytic enzymes, cytokines and chemokines, which are mitogenic for neoplastic cells, as well as endothelial cells involved in neoangiogenesis and lymphangiogenesis. These factors potentiate tumour growth, stimulate angiogenesis, induce fibroblast migration and maturation, and enable metastatic spread via engagement with either the venous or lymphatic 
networks.

 Cytokine and chemokine balances regulate neoplastic outcome. The balance of cytokines in any given tumour is critical for regulating the type and extent of inflammatory infiltrate that forms. Tumours that produce little or no cytokines or an overabundance of anti-inflammatory cytokines induce limited inflammatory and vascular responses, resulting in constrained tumour growth. In contrast, production of an abundance of pro-inflammatory cytokines can lead to a level of inflammation that potentiates angiogenesis, thus favouring neoplastic growth. Alternatively, high levels of monocytes and/or neutrophil infiltration, in response to an altered balance of pro-versus anti-inflammatory cytokines, can be associated with cytotoxicity, angiostasis and tumour regression. In tumours, interleukin-10 is generally a product of tumour cells and tumour-associated macrophages.

This is from an article called: Inflammation and cancer; Lisa M. Coussens^*†§ and Zena Werb^‡§

One of my big projects has concerned a study with the chemokine fraktalkine (FKN) and it’s receptor CX3CR1. This is just an interesting article I found…

Role of CX3CR1/CX3CL1 axis in primary and secondary involvement of the nervous
system by cancer
Federica Marchesi a, Marco Locatelli b, Graziella Solinas a, Marco Erreni a,
Paola Allavena a, Alberto Mantovani a,c,⁎

CX3CL1 or Fractalkine is a peculiar chemokine that can exist either in a soluble form, like all the other chemokines, and as a cell membrane molecule.

CX3CL1 is one of the most expressed chemokines in the central nervous system, where it regulates the communication between neurons, glia and microglia.

 Fig. 1. CX3CR1 in primary tumors of the nervous system and metastasis. Different tumors expressing CX3CR1 are represented, together with the organs or tissues which are the site of secondary localization. 

Fig. 2. Perineural invasion in pancreatic adenocarcinoma. 
(A) Histological section of pancreatic cancer (T) invading the perineural space (N, circled section).
Immunoreactivity with an anti-CX3CR1 depicts pancreatic tumor cells (magnification 40×).
(B) Schematic representation of some of the molecular mechanisms involved in perineural invasion. 
A nerve inside the pancreas developing a tumor is represented. 
Tumor cells adhere to neural cells, infiltrating the perineural space. 
Molecules involved in this interaction include the chemokine Fractalkine/Neurotactin (CX3CL1) expressed by neurons and its receptor CX3CR1 on tumor cells. 
Neurotropins secreted by neural and tumor cells sustain growth and survival of both intratumoral nerves and cancer cells.

Neutralisation of a virus is defined as the loss of infectivity through reaction of the virus whith specific antibody.

Virus is inoculated into cell culture and the presence of unneutralized virus may be detected by plaque assay.
Loss of infectivity can be achieved by bound antibody interfering with the release of the viral genome into the host cells.

There are two types of neutralization:

Reversible neutralization
- the process can be reversed by diluting teh antibody-antigen mixture within a short time of the formation of the antibody- antigen complexes (30mins).
It is thought that reversible neutralization is due to the interference with attachment of virions to the cellular receptors, f.ex the attachment of the hemagglutinin (HA) protein of influenza viruses to sialic acid.
The process requires that the surface of the virus is saturated with antibodies.

Stable neutralization
-with time antigen-antibody complexes usually become more stable (several hours) and the process cannot be reversed by dilution. The neutralized virus can be reactivated by proteolytic cleavage. Stable neutralization has a different mechanism to that of reversible neutralization.
The number of antibody molecules required for stable neutralization is smaller than that of reversible neutralization.. Even a single antibody can neutralize a virion, and such neutralization is generally produced by antibody molecules that establish contact with 2 antigenic sites on different monomers of a virion, greatly increasing the stability of the complexes.

Viral evolution must select for mutations that change the antigenic determinants inovlved in neutralization. In contrast, other antigenic sites would remain unchanged because mutations affecting them would not be selected for and could be detrimental.
A virus would thus evolve to develop a variety of  types differing in neutralization mechanisms.

Before a neutralization test is carried out, known components must be standardized. To identify a virus isolate, a known pretitred antiserum is used. Conversely, to measure the antibody response of an individual to a virus, a known pretitred virus is used. To titrate a known virus, serial tenfold dilutions of the isolate si prepared and inoculated into a cell culture or an animal.

The virus endpoint titre is the reciprocal of the highest dilution of virus that infects 50% of the host system, e.g. 50% of cell cultures develop cytpathic effect (CPE) or 50% of animals develop disease.
This endpoint dilution contains one 50% tissue culture infecting dose (TCID50) or one 50% lethal dose (LD50) of virus per unit volume. The concentration of virus generally used in the neutralization test is 100TCID50 or 100LD50 per unit volume.

Micrograph showing the viral cytopathic effect of herpes simplex virus (multi-nucleation, ground glass chromatin).

Likvor
Cerebrospinal fluid (CSF), Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord. In essence, the brain “floats” in it.
The CSF occupies the space between the arachnoid mater (the middle layer of the brain cover, meninges), and the pia mater (the layer of the meninges closest to the brain). It constitutes the content of all intra-cerebral (inside the brain, cerebrum) ventricles, cisterns, and sulci (singular sulcus), as well as the central canal of the spinal cord.
It acts as a “cushion” or buffer for the cortex, providing a basic mechanical and immunological protection to the brain inside the skull.
It is produced in the choroid plexus.

Functions

CSF serves four primary purposes:

1. Buoyancy: The actual mass of the human brain is about 1400 grams; however the net weight of the brain suspended in the CSF is equivalent to a mass of 25 grams.^[7] The brain therefore exists in neutral buoyancy, which allows the brain to maintain its density without being impaired by its own weight, which would cut off blood supply and kill neurons in the lower sections without CSF.^[8]
2. Protection: CSF protects the brain tissue from injury when jolted or hit. In certain situations such as auto accidents or sports injuries, the CSF cannot protect the brain from forced contact with the skull case, causing hemorrhaging, brain damage, and sometimes death.^[9]
3. Chemical stability: CSF flows throughout the inner ventricular system in the brain and is absorbed back into the bloodstream, rinsing the metabolic waste from the central nervous system through the blood-brain barrier. This allows for homeostatic regulation of the distribution of neuroendocrine factors, to which slight changes can cause problems or damage to the nervous system. For example, high glycine concentration disrupts temperature and blood pressure control, and high CSF pH causes dizziness and syncope.^[10]
4. Prevention of brain ischemia: The prevention of brain ischemia is made by decreasing the amount of CSF in the limited space inside the skull. This decreases total intracranial pressure and facilitates blood perfusion.

Monoclonal antibodies (mAb or moAb) are monospecific antibodies (having affinity for the same antigen) that are the same because they are made by one type of immune cell that are all clones of a unique parent cell.

Monoclonal antibodies can be created to purify substances, to which they specifically bind.

Monoclonal antibodies are typically made by fusing myeloma cells with the spleen cells from a mouse that has been immunized with the desired antigen.
Polyethylene glycol is used to fuse adjacent plasma membranes, but the success rate is low so a selective medium in which only fused cells can grow is used.
This is because myeloma cells have lost the ability to synthesize hypoxanthine-guanine-phosphoribosyl transferase (HGPRT), an enzyme necessary for the salvage synthesis of nucleic acids.

The selective culture medium is called HAT medium because it contains hypoxanthine, aminopterin, and thymidine.
This medium is selective for fused (hybridoma) cells. Unfused myeloma cells cannot grow because they lack HGPRT, and thus cannot replicate their DNA.
Unfused spleen cells cannot grow indefinitely because of their limited life span.
Only fused hybrid cells, referred to as hybridomas, are able to grow indefinitely in the media because the spleen cell partner supplies HGPRT and the myeloma partner has traits that make it immortal (as it is a cancer cell).

The hybridomas can be grown indefinitely in a suitable cell culture media, or they can be injected in mice (in the peritoneal cavity, the gut), they produce tumors containing an antibody-rich fluid called ascites fluid.

After obtaining either a media sample of cultured hybridomas or a sample of ascites fluid, the desired antibodies must be EXTRACTED.
The contaminants in the cell culture sample would consist primarily of media components such as growth factors, hormones, and transferrins.
In contrast, the in vivo sample is likely to have host antibodies, proteases, nucleases, nucleic acids, and viruses.
In both cases, other secretions by the hybridomas such as cytokines may be present.
There may also be bacterial contamination and, as a result, endotoxins that are secreted by the bacteria.

Various proteins can also be separated out along with the anions based on their isoelectric point (pI). For example, albumin has a pI of 4.8, which is significantly lower than that of most monoclonal antibodies, which have a pI of 6.1. In other words, at a given pH, the average charge of albumin molecules is likely to be more negative. Transferrin, on the other hand, has a pI of 5.9, so it cannot easily be separated out by this method. A difference in pI of at least 1 is necessary for a good separation.

ABRUPT END

ANTIBODY
Antibodies are gamma globulin proteins found in the blood or other bodily fluids of vertebrates. They are used by the immune system to identify and neutralize foreigh objects, such as bacteria and viruses.
They are made of basic structural units including 2 large heavy chains and 2 small light units. These form monomers with one unit, dimers with two units or pentamers with one unit.

Antibodies are produced by white blood cells called plasma cells. There are several different types of antibody heavy chains, and several different kinds of antibodies, which are grouped into different isotypes bases on which heavey chain they possess.
Five different antibody isotypes are know in mammals. They perform different roles and help direct the appropriate immune response for each different type of foreign object they encounter.

A small region at the tip of the protein is extremely variable, allowing millions of antibodies with slightly different tip structures called antigen binding sites to exist.
This region is know as the hypervariable region and each variant can bind to a different target known as antigen.
The part of the antigen which is recognized by an antibody is called epitope. The epitopes bind with their antibody in a highly specific interaction (induced fit), and this allows antibodies to identify and bind only their unique antigen.
Recognitino of an antigen by an antibody TAGS it for attack by other parts of the immune system. Antibodies can also neutralize targets directly by binding to a part of apathogen that it needs to cause an infection.

The divers population of antibodies is generated by random combinations of a set of gene segments that encode different antigen binding sites (paratopes) followed by random mutations in this area of the anitbody gene, creating more diversity.
Antibody genes also re-organize in a process called CLASS SWITCHING that changes the base of the heavy chain to another, creating a different isotype of the antibody that retains the antigen specific variable region. This allows a single antibody to be used by several differnt parts of the immune system. Production of antibodies is the main function of the humoral immune system.

FORMS
Surface immunoglobulin (Ig) is attached to the membrane of the effector B cells by its transmembrane region, while antibodies are the secreted form of Ig and lack the trans membrane region so that antibodies can be secreted into the bloodstream and body cavities.
As a result, surface Ig and antibodies are IDENTICAL except for the TRANSMEMBRANE REGIONs.
Therefore, they are considered two forms of antibodies:

• SOLUBLE FORM
• MEMBRANE-BOUND FORM

(Parham)

The membrane-bound form of an anitbody may be called a surface immunoglobulin (sIg) or a membrane immunoglobulin (mIg).
It is part of the B cell receptor (BCR), which allows a B cell to detect when a specific antigen is present in the antibody and triggers B cell activation.
The BCR is composed of surface-bound IgD or IgM antibodies and associated Ig-alfa and Ig-beta heterodimers, which are capable of signal transduction.
A typical human B cell will have 50,000 to 100,000 antibodies bound to its surface.
Upon antigen binding, they cluster in large patches, which can exceed 1 micrometer in diameter, on lipid rafts that isolate the BCRs from most other cell signaling receptors.
These patches may improve the efficiency of the cellular immune response. In humans, the cell surface is bare aorund the B cell receptors for several thousand ångströms, which further isolates the BCRs from competing influences.

A Intracellular space or cytosol
B Extracellular space or vesicle/Golgi apparatus lumen
1. Non-raft membrane
2. Lipid raft
3. Lipid raft associated transmembrane protein
4. Non-raft membrane protein
5. Glycosylation modifications (on glycoproteins and glycolipids)
6. GPI-anchored protein
7. Cholesterol
8. Glycolipid

ISOTYPES
Antibodies come in different varieties known as ISOTYPES or classes. in placental mammals there are five anitbody isotypes called:
IgA   IgD   IgE   IgG   IgM

Ig stands for immunoglobulin and they differ in biological properties, functional locations and ability to deal with different antigens.
IgA (2 types) – found in mucosal areas, like gut, respiratory tract, urogenital tract and prevents colonization by pathogens. Also in saliva, breast milk, and tears.
IgD (1 type)  -  fxn as an antigen receptor on B cells that haven’t been exposed to antigens. It has been shown to activate basophils and mast cells to produce antimicrobial factors.
IgE (1 type)  – binds to allergens and triggers histamine release from mast cells and basophils and is involved in allergy. Also protects against parasitic worms.
IgG (4 types) In its four forms, it provides the majority of antibody-based immunity against invading pathogens. The only antibody capable of crossing the placenta to give passive immunity to fetus.
IgM (1 type)  – expressed on the surface of B cells and in a secreted form with very high avidity. Eliminates pathogens in the early stages of B cell mediated (humoral) immunity before there is sufficient IgG.

The antibody isotype of a B cell changes during cell development and activation. Immature B cells, which have never been exposed to an antigen, are known as NAIVE B CELLS and express only the IgM isotype in a cell surface bound form. B cells begin to express both IgM and IgD when they reach maturity – the co-expression of both these immunoglobulin isotypes renders the B cell ‘mature’ and ready to respond to antigen. B cell activation follows engagement of the cell bound anitbody olecule with an antigen, causing the cell to divide and DIFFERENTIATE into an antibody producing cell called a PLASMA CELL. In this activated form. the B cell starts to produce antibody in a secreted form rather than a membrane-bound form.

Several immunoglobulin domains make up the two heavy chains (red and blue) and the two light chains (green and yellow) of an antibody. The immunoglobulin domains are composed of between 7 (for constant domains) and 9 (for variable domains) β-strands.

STRUCTURE
Antibodies are heavy (ca 150kDa) globular plasma proteins. They have sugar chains added to some of their amino acid residues. In other words, antibodies are GLYCOPROTEINS. the basic funcitonal unit of each anitbody is an immunoglobulin (Ig) monomer (containing only one Ig unit); secreted antibodies can also be dimeric with 2 ig units as with IgA, tetrameric with four Ig units like TELEOST FISH IgM, or pentameric with five Ig units, like mammalian IgM.
The variable parts of an anitbody are its V regions and the constant part is its C region.

Immunobulin domains
The Ig monomer ias “Y”-shaped molecule that consists of four polpeptide chains; tow identical heavy chains and 2 identical light chains connected by DISULFIDE BONDS. Each chain is composed of strucutral domains called immunoglobulin domains. These domains contain about 70-110 amino acids and are classified into different categories (IgV or IgC) according to their size and function. They have a characteristic immunoglobulin fold in which 2 BETA SHEETS create a ‘sandwhich’ shape, held together by interactions between conserved CYSTEINES and other charged amino acids.

Heavy chain
There are 5 types of mammalian ig heavy chain denoted by Greek letters: alfa- delta, epsilon, gamma and mu.
The type of heavy chain present defines the class of antibody; these chains arae found in IgA, IgD, IgE, IgG and IgM antibodies. Distinct heavy chains differ in size and composition; alfa and gamma contain approximately 450 amino acids, while mu and epsilon have approximately 550 amino acids.

Each heavy chain has 2 regions, the CONSTANT region and the VARIABLE region. The constant region is identical in all antibodies of the same isotype, but differs in antibodies of different isotypes.
Heavy chains, gamma and delta, have a constant region composed of three tandem (in a line) ig domains, and a hinge region for added flexibility, heavy chains mu and epsilon have a constant region composed of four immunoglobulin domains. The variable region of the heavy chain differs in antibodies produced by different B cells, but is the same for all antibodies produced by a single B cell or B cell clone. The variable region of each heavy chain is approximately 110 amino acids long and is composed of a single Ig domain.

Light chain
In mammals there are 2 types of immunoglobulin light chain, which are called LAMBDA and KAPPA.
A light chain has two successive domains: one constant domain and one variable domain. The approximate length of a light chain is 211 to 217 amino acids. Each anitbody contains 2 light chains that are always identical; only one type of light chain, kappa or lambda, is present per anitbody in mammals. Other tyåpes of light chains, such as the IOTA  chain, are found in lower vertebrates likeChondichtyes and Teleostei.

Function
Activated B cells differentiate into either antibody-producing cells called plasma cells that secrete soluble antibody or memory cells that survive in the body for years afterward in order to allow the immune system to remember an antigen and respond faster upon future exposures. Since antibodies exist freely in the bloodstream, they are said to be part of the humoral immune system. Circulating antibodies are produced by clonal B cells that specifically respond to only one antigen (an example is a virus capsid protein fragment). Antibodies contribute to immunity in three ways: they prevent pathogens from entering or damaging cells by binding to them; they stimulate removal of pathogens by macrophages and other cells by coating the pathogen; and they trigger destruction of pathogens by stimulating other immune responses such as the complement pathway.

Activation of complement
Antibodies that bind to surface antigens on, for example, a bacterium attract the first component of the complement cascade with their Fc region and initiate activation of the “classical” complement system.^[22] This results in the killing of bacteria in two ways.^[6] First, the binding of the antibody and complement molecules marks the microbe for ingestion by phagocytes in a process called opsonization; these phagocytes are attracted by certain complement molecules generated in the complement cascade. Secondly, some complement system components form a membrane attack complex to assist antibodies to kill the bacterium directly.

Activation of effector cells
To combat pathogens that replicate outside cells, antibodies bind to pathogens to link them together, causing them to agglutinate. Since an antibody has at least two paratopes it can bind more than one antigen by binding identical epitopes carried on the surfaces of these antigens. By coating the pathogen, antibodies stimulate effector functions against the pathogen in cells that recognize their Fc region.

Those cells which recognize coated pathogens have Fc receptors which, as the name suggests, interacts with the Fc region of IgA, IgG, and IgE antibodies. The engagement of a particular antibody with the Fc receptor on a particular cell triggers an effector function of that cell; phagocytes will phagocytose, mast cells and neutrophils will degranulate, natural killer cells will release cytokines and cytotoxic molecules; that will ultimately result in destruction of the invading microbe. The Fc receptors are isotype-specific, which gives greater flexibility to the immune system, invoking only the appropriate immune mechanisms for distinct pathogens.

Natural antibodies
Human and higher primates also produce ‘natural antibodies’ which are present in serum before viral infection. natural antibodies have been defined as anitbodies that are produced without any previous infection, vaccination, other foreign antigen exposure or passive immunization. These antibodies can activate the classical complement pathway leading to lysis of enveloped virus particles long before the adaptive immune response isactivated. Many natural antibodies are directed against the disaccharide galactose alfa (1,3)-glactose (alfa-Gal), which is found as a terminal sugar on glycosylated cell surface proteins, and generated in response to production of this sugar by bacteria contained i the human gut. Rejection of xenotransplanted organs is thought to be, in part, the result of natural antibodies circulating in the serum of the recipient binding to alfa-Gal antigens expressed on the donor tissue.

Presence of neutralizing antibodies to HSV were found in the serum of previously infected adults. Only individuals with neutralizing antibodies developed recurrent lesions. Remarkably, measles and rubella antibodies are associated with protection from subsequent episodes of the disease.

National Herpes Hotline 
(919) 361-8488

National Herpes Resource Center 
herpesnet@ashastd.org

One significant advance of our understanding of herpes infection was the detection of antigenic differences between HSV types. Already in 1968, antigenic and biologic differences between HSV-1 and HSV-2 were found by Nahmias and Dowdle. The observation was that HSV-1 was more frequently associated with nongenital infection whereas HSV-2 was associated with genital disease.

Infection of epithelial cells in the mucosal surface gives rise to productive replication, resulting in the production of progeny virions, which can spread to infect additional epithelial cells. Virus enters innervating sensory neurons, and nucleocapsids are transported to the neuronal cell body. The viral DNA is released into the neuronal nucleus and circularizes. Circular viral DNA persists in the neuronal cell nucleus, and the latency-associated transcript is expressed. b | Upon reactivation, viral lytic gene expression is initiated, and newly formed capsids are transported to the axonal termini. Infectious virus is released from the axon and infects epithelial cells, resulting in recurrent infection and virus shedding.
 

God natt, noapte buna, spakujna nocin and good night herpes wherever you are.

Book tip of the day:
How Pathogenic Viruses work   – found on shelf in the office

Review Macrophages and cytokines in the early defence against herpes simplex virus – S. Ellermann-Eriksen:

HSV-1 and HSV-2 are old viruses, with a history of evolution shared with humans.
Thus, it is generally well-adapted viruses (thus), infecting many of us without doing much harm, and with the capacity of hiding in our neurons for life. No harm.

Normally, the primary HSV infection is asymptomatic, and a crucial element (HSV infection or asymptomatic HSV infection?) in the early restriction of virus replication (asymptomatic infection crucial to restriction of virus replication by aid of immune system) and thus (thus?) avoidance of symptoms from the infection is the concerted action of different arms of the innate immune response.

HSV infection is asymptomatic normally. Innate immune system arranges actions to make herpes infection asymptomatic, which benefits both host and virus. Virus and host – we live in forced symbiosis.

There are multiple heros in the united universe, which exists.

?

Virus infection or innate immune system. I am confused. I need to think more.

From PNAS – Biography of Patricia G. Spear
Much of our current under- standing of the virus is a result of the pioneering work of Patricia G. Spear. Through years of dedication, she has identified and characterized the proteins present on the surfaces of viruses and cells that allow HSV to enter its host.

At Chicago, Spear conducted her the- sis research on HSV under the guidance of Bernard Roizman. She remembers, ‘‘I was just fascinated with what the virus did to cells. I thought it was mindblowing how the virus could change the shape and behavior of the cell before killing it off.’’
This fascination marked the beginning of a career devoted almost exclusively to HSV research. Dur- ing her graduate school days, Spear was among the first to identify the many protein and glycoprotein constituents of HSV. With some difficulty, she purified the virion from infected cells and used electrophoresis to determine the number of viral proteins.
‘‘You have to remember that in those days, the late ’60s, we didn’t have the tools available today,’’ she recalls fondly.
‘‘The biggest advances at that time included the Laemmli gels that allowed you to separate proteins of different sizes by electrophoresis! It became clear that the virion had at least thirty proteins, if not more, so it was a much more complicated structure than anyone had realized.’’

Spear studied the developing immune system in mice, determining when the spleen and thymus became populated with functional T cells and B cells ( Spear, P. G., Wang, A. L., Rutishauser, U. & Edelman, G. M. (1973) J. Exp. Med. 138, 557–573.; Spear, P. G. & Edelman, G. M. (1974) J. Exp. Med. 139, 249–263.).

She described various glycoproteins of the HSV viral envelop: ‘‘This was slow, slogging work of devel- oping antibodies, trying to characterize which glycoproteins were in the virion, and analyzing viral mutations.’’

HSV Glycoproteins and Viral Binding

In addition to describing the surface glycoproteins, Spear characterized HSV glycoprotein functions in cell fusion and immune responses.
By examining temperature-sensitive viral mutants, she determined that one of the viral glycoproteins, gB, promotes cell fusion whereas another, gC, could modulate or suppress fusion activity (Manservigi, R., Spear, P. G. & Buchan, A. (1977) Proc. Natl. Acad. Sci. USA 74, 3913–3917.).
Cell fusion occurs in HSV lesions in vivo and may be one mechanism by which the virus spreads from cell to cell. In addition, Spear and colleagues determined that viral glycoprotein gE bound the Fc re- gion of immunoglobulin G (Baucke, R. B. & Spear, P. G. (1980) J. Virol. 32, 779 –789.) and that gC could protect virus from neutraliza- tion by complement (McNearney, T. A., Odell, C., Holers, V. M., Spear, P. G. & Atkinson, J. P. (1987) J. Exp. Med. 166, 1525–1535.).

Later, Spear turned her focus to the cellular side of the HSV infection equation by searching for cell-surface receptors that were important for viral entry. She determined that heparan sulfate, a carbohydrate component of certain pro- teoglycans, serves as the initial cell- surface receptor for both HSV serotypes (WuDunn, D. & Spear, P. G. (1989) J. Virol. 63, 52–58.; Herold, B. C., WuDunn, D., Soltys, N. & Spear, P. G. (1991) J. Virol. 65, 1090–1098.; Shieh, M.-T., WuDunn, D., Montgomery, R. I., Esko, J. D. & Spear, P. G. (1992) J. Cell Biol. 116, 1273–1281.; Herold, B. C., Visalli, R. J., Susmarski, N., Brandt, C. R. & Spear, P. G. (1994) Br. J. Gen. Virol. 75, 1211–1222.)

Furthermore, analysis of viral mutants revealed that two of the viral glycoproteins, gB and gC, could mediate binding of HSV to cell-surface heparan sulfate.
Spear began a labor-intensive project of expression cloning to identify the cell-surface proteins that mediate HSV entry.
As an experimental tool, they used Chinese hamster ovary (CHO) cells, which ex- pressed heparan sulfate on the surface but were resistant to viral entry.
By transfecting the CHO cells with cDNA libraries from HSV-susceptible human cells, they identified plasmids that could render CHO cells vulnerable to viral penetration.
Ultimately, Spear and colleagues identified three different classes of entry receptors, discoveries that she considers her greatest contribution to HSV research.

1. The first mediator of HSV entry to be identified was a cell-surface protein called herpes virus entry mediator (HVEM), cloned by Rebecca Montgom- ery (Montgomery, R., Warner, M. S., Lum, B. J. & Spear, P. G. (1996) Cell 87, 427–436.).
2. Next, Morgyn Warner and Robert Geraghty characterized two members of the immunoglobulin super- family, nectin-1 (originally HveC) and nectin-2 (originally HveB), as the sec- ond class of HSV entry receptors (Warner, M. S., Geraghty, R. J., Martinez, W. M., Montgomery, R. I., Whitbeck, J. C., Xu, R., Eisen- berg, R. J., Cohen, G. H. & Spear, P. G. (1998) Virology 246, 179–189.; Geraghty, R. J., Krummenacher, C., Cohen, G. H., Eisenberg, R. J. & Spear, P. G. (1998) Science 280, 1618 –1620.). Nectin-1 is expressed in human cells of epithelial and neuronal origin and is the prime candidate receptor that allows HSV to spread on mucosal surfaces and infect cells of the nervous system.
3. The third class of HSV entry recep- tors emerged when Spear’s postdoctoral fellow, Deepak Shukla, was cloning the mouse homologs of HVEM, nectin-1, and nectin-2. ‘‘He discovered something unusual—that the enzyme 3-O-sulfo- transferase could actually make the CHO cells susceptible to HSV entry,’’ said Spear. Through an extensive collab- oration with Robert Rosenberg at the Massachusetts Institute of Technology in Cambridge, MA, Jeffrey Esko at the University of California at San Diego, and Gary Cohen and Roselyn Eisenberg at the University of Pennsylvania in Philadelphia, Spear and Shukla determined that 3-O-sulfotransferase gener- ated viral entry receptors by modifying cell-surface heparan sulfate (Shukla, D., Liu, J., Blaiklock, P., Shworak, N. W., Bai, X., Esko, J. D., Cohen, G. H., Eisenberg, R. J., Rosenberg, R. D. & Spear, P. G. (1999) Cell 99, 13–22.). Spear recalls this serendipitous finding with amusement, ‘‘So now we had heparan sulfate playing two roles: plain vanilla heparan sulfate mediating virus binding and interactions with the two viral gly- coproteins gB and gC, and the specially modified 3-O-sulfated heparan sulfate acting as an entry receptor.’’ Through collaborations with Gary Cohen and Roselyn Eisenberg, Spear established that HSV gD is the ligand for all three known classes of HSV entry receptors (Whitbeck, J. C., Peng, C., Lou, H., Xu, R., Willis, S. H., Ponce de Leon, M., Peng, T., Nicola, A. V., Montgomery, R. I., Warner, M. S., et al. (1997) J. Virol. 71, 6083– 6093.; Krummenacher, C., Nicola, A. V., Whitbeck, J. C., Lou, H., Hou, W., Lambris, J. D., Ger- aghty, R. J., Spear, P. G., Cohen, G. H. & Eisenberg, R. J. (1998) J. Virol. 72, 7064– 7074.).

• She and her colleagues are working to understand how the virus physically fuses with the cell membrane. They already have determined that fusion depends on the expression of an entry receptor for gD as well as four viral glycoproteins: gB, gD, gH, and gL (18). Given this, Spear says the obvious question is, ‘‘Why does this virus require four different glycopro- teins and a gD receptor to initiate fu- sion when many viruses can do it with one glycoprotein and receptor?’’

• The second major focus of her research is to understand the relative roles of all of the cellular entry receptors in HSV disease, such as how the differential expression of entry receptors on various cell populations influences infection and pathogenesis.

In her Inaugural Article (Manoj, S., Jogger, C. R., Myscofski, D., Yoon, M. & Spear, P. G. (2004) Proc. Natl. Acad. Sci. USA 101, 12414 –12421.), Spear and colleagues used mutational analysis to determine which domains of viral gD interact with the various entry receptors, HVEM, nectin-1, nectin-2, or 3-O- sulfated heparan sulfate, to mediate fusion.
They generated a panel of gD mutants, all of which exhibit restricted receptor usage, but each of which retains activity with a different receptor or set of receptors.
‘‘Now, when we build these mutations back into the virus,’’ she says, ‘‘we can challenge mice with these viruses and see what kind of cells become infected and how this restriction of receptor specificity alters pathogenesis.’’ Spear speculates ‘‘that the virus probably uses different entry receptors to get into different cell types.’’
For example, Spear postulates
‘‘Why does this virus require four different glycoproteins and a gD receptor?’’
that the entry receptor most important for infecting cells of epithelial and neuronal origin is probably nectin-1, whereas HVEM is probably most important for infection of lymphocytes and other leukocytes.

Spear concedes that, ‘‘Before our work with HSV and others’ work with HIV, people tended to think of viral entry as: a virus binds a single receptor, presto chango, it’s in the cell. I think we have broadened people’s perspectives that viral entry is a much more complicated process than any of us imagined.’’