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A human infecting coronavirus (viral pneumonia) called 2019 novel coronavirus, 2019-nCoV was found in the fish market at the city of Wuhan, Hubei province of China on December 2019.

The 2019-nCoV shares an 87% identity to the 2 bat-derived severe acute respiratory syndrome 2018 SARS-CoV-2 located in Zhoushan of eastern China. 2019-nCoV has an analogous receptor-BD-structure to that of 2018 SARS-CoV, even though there is a.a. diversity so thus the 2019-nCoV might bind to ACE2 receptor protein (angiotensin-converting enzyme 2) in humans.

While bats are possibly the host of 2019-nCoV, researchers suspect that animal from the ocean sold at the seafood market was an intermediate host. RSCU analysis proposes that the 2019-nCoV is a recombinant within the viral spike glycoprotein between the bat coronavirus and an unknown coronavirus.

The SARS CoV-2 3CL protease (C30 Endopeptidase) derived from human SARS-CoV-2 is a C30-type cysteine protease situated in the NS3 segment. SARS CoV-2 3CL protease biological functionality is needed to process viral polyproteins to functional complete units. SARS CoV-2 3CL protease (main protease) is the core protease protein in CoV and corresponds to non-structural protein 5. SARS CoV-2 3CL cleaves the CoV polyprotein at 11 locations. SARS CoV-2 3CL protease has a cysteine-histidine catalytic dyad at its active site and cleaves a Gln–(Ser/Ala/Gly) peptide bond. SARS CoV-2 3CL protease at position P1 cleaves the bond between the glutamine and serine/alanine/glycine. SARS CoV-2 3CL protease is necessary in the processing of the CoV replicase polyprotein.

CD21 is expressed strongly on mature B cells, follicular dentritic cells and weakly on immature thymocytes and T lymphocytes. In B-cell ontogeny, CD21 appears after the pre-B-stage, is maintained during peripheral B-cell development and is lost upon terminal differentiation into plasma cells. CD21 expression is also gradually lost after stimulation of B cells in vitro. CD21 functions as receptor for C3d, C3dg and iC3b Complement components, for EBV and for IFNalpha. CD21 binds to CD23 and associates with CD19, CD81 and Leu13 to form a large signal-transduction complex involved in B cell activation.

HER-2/neu (erbB-2) encodes an 185-kDa orphan receptor tyrosine kinase that is constitutively active as a dimer and displays potent oncogenic activity when overexpressed. Herstatin, as the product of alternative HER-2 transcript, retains intron 8. The herstatin mRNA is expressed in normal human fetal kidney and liver, but is at reduced levels relative to p185HER-2 mRNA in carcinoma cells that contain an amplified HER-2 gene. Herstatin appears to be an inhibitor of p185HER-2, because it disrupts dimers, reduces tyrosine phosphorylation of p185, and inhibits the anchorage-independent growth of transformed cells that overexpress HER-2.

Receptors across the cell membrane interact with some viral glycoproteins therefor enabling HSV to enter the host cell. The HSV enter through pores created by the binding of particular receptors across the cell membrane with the virus's coating envelope, following by a fusion of the HSV and the host cell. HSV enters the host cell through the same mechanism and stages as other viruses do. Initially, matching receptors across the virus's envelope and host cell's membrane interacts and bring the two together. During the transitional stage, begins fusion between the host cell and virus (hemifusion state). The closing stage happens when a steady pore was made; through these pores the virus's particles enter the cell.

Helicobacter pylori is a Gram negative bacteria which colonizes in the human stomach and stimulates gastric mucosal inflammations leading to acute gastritis-associated diseases among them are atrophic gastritis, peptic ulcer and gastric cancer.

H. pylori is found in half of the world’s population and is defined as a group I carcinogens. .

An important virulence factor of H. pylori is Cytotoxin-associated gene A (CagA) which is located at the end of an approximately 40-kb cluster of genes called cag pathoge¬nicity island (PAI).

Cag PAI encodes a type-IV secretion system and transfers CagA protein into the intracellular region of gastric epithelial cell.

This relocation induces cellular hyper proliferation, apoptosis and leading to failure of gastric epithelial cell in maintaining its normal cytoskeletal structure. Furthermore it increases the secretion of cytokines such as tumor necrosis factor (TNF) and interleukin (IL) 1, 6 and 8 by the epithelial cells.

The IL-8 leads to extreme inflammatory responses and also stimulates the production of oxygen free radicals that could cause DNA damage to adjacent cells and lead to genetic modifications of gastric epithelial cells which are carcinogenic.

The life cycle of Toxoplasma gondii has 2 phases. The coccidia like takes place only in members of the Felidae family which makes these animals the parasite's primary host. The asexual part of the life cycle can take place in any warm-blooded animal, like other mammals (including felines) and birds. T. gondii constructing daughter scaffolds within the mother cell. In the intermediate hosts (including felines), the parasite invades cells, forming intracellular so-called parasitophorous vacuoles containing bradyzoites, the slowly replicating form of the parasit. Vacuoles form tissue cysts mainly within the muscles and brain. Since they are within cells, the host's immune system does not detect these cysts. Resistance to antibiotics varies, but the cysts are very difficult to eradicate entirely. Within these vacuoles T. gondii propagates by a series of binary fissions until the infected cell eventually bursts and tachyzoites are released. Tachyzoites are the motile, asexually reproducing form of the parasite. Unlike the bradyzoites, the free tachyzoites are usually efficiently cleared by the host's immune response, although some manage to infect cells and form bradyzoites, thus maintaining the infection. Recombinant Toxoplasma Gondii P35 (GRA8)) is an antigen used to test the specific Toxoplasma gondii antibody for the diagnosis of Toxoplasma gondii infection.

Lassa virus, which is a member of the Arenaviridae virus family, causes acute viral hemorrhagic fever. It was first reported in 1969 in the town of Lassa, in Borno State, Nigeria. Natal multimammate mouse is the primary reservoir of Lassa virus, found in sub-Saharan Africa. The virus is transmitted by contact with the feces or urine of animals, contributing to its high rate of incidence. Lassa fever occurs generally in West Africa. Lassa fever results in 300,000 to 500,000 cases annually and causes about 5,000 deaths each year. Outbreaks of this disease have been observed in Nigeria, Liberia, Sierra Leone, Guinea, and the Central African Republic. Protein structure: Lassa virus genome is comprised of two single-stranded RNA molecules defined as small (S) and large (L). Two genes on the S segment encode the nucleoprotein (NP) and two envelope glycoproteins (GP1 and GP2); while, the L segment encodes the viral polymerase (L protein) and RING finger Z matrix protein. GP1 subunit serves a putative role in receptor binding, while the structure of GP2 subunit is consistent with viral transmembrane fusion proteins. NP is a virion protein which binds and protects the viral RNA.

ARG2 participates in the regulation of extra-urea cycle arginine metabolism and also in down-regulation of nitric oxide synthesis. Extrahepatic arginase functions to regulate L-arginine bioavailability to NO synthase. Since NO synthase is found in the penile corpus cavernosum smooth muscle, the clitoral corpus cavernosum and the vagina, ARG2 takes part in both male and female sexual arousal and therefore a potential target for the treatment of male and female sexual arousal disorders.

Hepatoma-derived growth factor, related protein 3 (HDGFRP3/HDGF2) is the original member of a family of polypeptides labeled HDGF related proteins (HRPs). The HDGF2 protein augments DNA synthesis and may play a part in cell proliferation. HDGF2 is expressed primarily in the testis and the brain, to an intermediate extent in the heart, and to a slight extent in the ovaries, kidneys, spleen, and liver in humans.

A fusion tag called FLAG consists of eight amino acids (AspTyrLysAspAspAspAspLys) including an enterokinase-cleavage site. FLAG is specifically designed for immunoaffinity chromatography. It allows elution under non-denaturing conditions. Several antibodies against this peptide have been developed. One antibody denoted as M1 binds the peptide in the presence of bivalent metal cations preferably Ca(+). Elution is effected by chelating agents. Another strategy is competitive elution with excess of free Flag Peptide.
The FLAG peptide purifies and detects recombinant fusion proteins. FLAG peptide is useful in Western blotting, immunocytochemistry, immunoprecipitation, flow cytometry, protein purification, and in the study of protein-protein interactions, cell ultrastructure, and protein localization. Flag peptide is a hydrophilic tag which significantly improves the detection and purification of recombinant fusion proteins.

VZV is closely related to the herpes simplex viruses(HSV), sharing much genomehomology. The known envelope glycoproteins (gB, gC, gE, gH, gI, gK, gL) correspond with those in HSV, however there is no equivalent of HSV gD. VZV virons are spherical and 150-200 nm in diameter. Their lipidenvelope encloses the nucleocapsid of 162 capsomeres arranged in a hexagonalform. Its DNAis a single, linear, double-stranded molecule, 125,000 nt long. The virus is very susceptible to disinfectants, notably sodium hypochlorite. Within the body it can be treated by a number of drugs and therapeutic agents including aciclovir, zoster-immune globulin(ZIG), and vidarabine.

Eotaxin-2, also called MPIF2 & Ck?6, is a novel CC chemokine produced by activated monocytes and T lymphocytes. Eotaxin-2 selectively chemoattracts cells expressing CCR3 including eosinophils, basophils, Th2 T cells, mast cells, and certain subsets of dendritic cells. Furthermore, Eotaxin-2 inhibits the proliferation of multipotential hematopoietic progenitor cells. The mature protein, which includes C-terminal truncation, contains 78 amino acids (92 amino acids for the mouse homolog, without C-terminal truncation).
CCL24 functions as a chemotactic chemokine for resting t-lymphocytes, and eosinophils. CCL24 has lower chemotactic activity for neutrophils but none for monocytes and activated lymphocytes. CCL24 is a strong suppressor of colony formation by a multipotential hematopoietic progenitor cell line and binds to CCR3.

His tag peptide also called polyhistidine-tag is chain of amino acids that are attached to proteins and consist of at least six histidine (6xHis, Hexa Histidine) residues, often at the N- or C-terminus of the protein. Polyhistidine-tags are used for affinity purification of genetically engineered proteins.

Phosphomevalonate kinase (PMVK) is a cytosolic enzyme. PMVK is expressed highly in the heart, liver, skeletal muscle, kidney and pancreas and slightly lower in the brain, placenta, and lung. PMVK catalyzes the conversion of mevalonate 5-phosphate into mevalonate 5-diphosphate in the fifth reaction of the cholesterol biosynthetic pathway. Induced by sterol, PMVK participates in isopentenyl diphosphate biosynthesis via the mevalonate pathway.

CD3-epsilonpolypeptide (CD3E) along with CD3-gamma, -delta and -zeta, and the T-cell receptor alpha/beta and gamma/delta heterodimers, creates the T-cell receptor-CD3 complex. This complex has an imperative role in coupling antigen recognition to a number of intracellular signal-transduction pathways. The genes encoding the epsilon, gamma delta polypeptides are found in the same cluster on chromosome 11. The epsilon polypeptide plays a vital role in T-cell development. CD3E gene defects cause immunodeficiency. CD3E is also linked to a susceptibility to type I diabetes in women.

Asialoglycoprotein Receptor 2 (ASGR2) is a hetero-oligomeric protein comprised of major and minor subunits, encoded by different genes. ASGR2 is a subunit of the asialoglycoprotein receptor; it is the less abundant minor subunit. The ASGR2 receptor is a transmembrane protein, which has a crucial role in serum glycoprotein homeostasis by mediating the endocytosis and lysosomal degradation of glycoproteins with exposed terminal galactose or N-acetylgalactosamine residues.

A 16-kDa peptide hormone secreted from white adipocytes and implicated in the regulation of food intake and energy balance. Leptin provides the key afferent signal from fat cells in the feedback system that controls body fat stores.

GSTO1 belongs to the theta class glutathione S-transferase-like (GSTTL) protein family. GSTO1 is expressed in a broad array of human tissues and exhibits glutathione-dependent thiol transferase and dehydroascorbate reductase activities as well as catalyzing the reduction of monomethylarsonate which is an intermediate in the pathway of arsenic biotransformation. Furthermore, GSTO1 shields from oxidative stress which is a risk factor for Alzheimer disease, vascular dementia and stroke. GSTO1 is abundant in alveolar macrophages and airway secretions, with the levels reduced in chronic obstructive pulmonary disease patients. In mouse, the GSTO1 protein acts as a small stress response protein, probably involved in cellular redox homeostasis.

Cyclophilin B (also known as PPIB, peptidylpropyl isomerase B) is a cyclosporine-binding protein and is mainly located within the endoplasmic reticulum. It is associated with the secretory pathway and released in biological fluids. This protein can bind to cells derived from T- and B-lymphocytes, and may regulate cyclosporine A-mediated immunosuppression.

NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 5 (NDUFA5) is a member of the complex I NDUFA5 subunit family. The human NDUFA5 gene codes for the B13 subunit of complex I of the respiratory chain that transfers electrons from NADH to ubiquinone. The NDUFA5 protein localizes to the inner mitochondrial membrane as part of the seven component-containing, water soluble 'iron-sulfur protein' (IP) fraction of complex I, even though its exact role is undetermined.

ERCC1 polypeptide is essential for nucleotide excision repair (NER) of damaged DNA and is homologous to Saccharomyces cerevisiae RAD10, which takes part in repair and mitotic intra-chromosomal recombination. NER mechanism includes dual incisions on both sides of the damage catalyzed by two nucleases. In mammalian cells XPG cleaves 3' of the DNA lesion while the ERCC1-XPF complex makes the 5' incision.

PDE6H belongs to the rod/cone cGMP-PDE gamma subunit family, which selectively catalyze the hydrolysis of 3 cyclic phosphate bonds in adenosine and/or guanine 3,5 cyclic monophosphate (cAMP and/or cGMP). This family regulates the cellular levels, localization and duration of action of these second messengers by controlling the rate of their degradation. PDE6H is the inhibitory (or gamma) subunit of the cone-specific cGMP phosphodiesterase, which is atetramer composed of two catalytic chains (alpha and beta), and two inhibitory chains (gamma). PDE6H is particularly expressed in the retina, and is implicated in the transmission and amplification of the visual signal. Mutations in PDE6H have been associated with retinal cone dystrophy type 3A.

MAGE belongs to the MAGE gene family, that comprises 12 known genes, of which 6 are expressed in tumors. The Melanoma-associated antigen 3 genes were originally isolated from different kinds of tumors, and based on their virtually limited tumor-specific expression in adult tissues, they were used as targets for cancer immunotherapy. MAGEA3 is a tumor-specific antigen extensively expressed in solid and hematologic malignancies, but not in normal tissues, with the exclusion of testis and placenta. Consequently, MAGEA3 is an outstanding candidate tumor antigen.