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SARS Coronavirus is an enveloped virus containing three outer structural proteins, namely the membrane (M), envelope (E), and spike (S) proteins. Spike (S)-glycoprotein of the virus interacts with a cellular receptor and mediates membrane fusion to allow viral entry into susceptible target cells. Accordingly, S-protein plays an important role in virus infection cycle and is the primary target of neutralizing antibodies.It has recently been shown that SARS is caused by a human coronavirus. Human coronaviruses are the major cause of upper respiratory tract illness in humans, such as the common cold. Coronaviruses are positive-stranded RNA viruses, featuring the largest viral RNA genomes known to date (27-31 kb). The first step in coronavirus infection is binding of the viral spike protein, a 139-kDa protein, to certain receptors on host cells. The spike protein is the main surface antigen of the coronavirus. The most prominent protein in the culture supernatants infected with SARS virus is a 46 kDa nucleocapsid protein. This suggests that the nucleocapsid protein is a major immunogen that may be useful for early diagnostics.

CD40 is part of the TNF-receptor superfamily. CD40 is a necessary mediator for vast range of immune and inflammatory responses together with T cell-dependent immunoglobulin class switching, memory B cell growth, and germinal center formation. The transcription factor AKNA regulates the expression of CD40 and its ligand, which is vital for homotypic cell interactions. Adaptor protein TNFR2 interacts with CD40 and serves as a mediator of the signal transduction. The interaction of CD40 and its ligand is crucial for amyloid-beta-induced microglial activation, and thus is thought to be an early event in Alzheimer disease pathogenesis. CD40 is the receptor for TNFSF5/CD40L.

Yersinia enterocolitica is a Gram-negative bacillus-shaped bacterium, which is a member of the Enterobacteriaceae family. Y.Enterocolitica is motile at temperatures between 22-29°C, however becomes non-motile at normal human body temperature. Y. Enterocolitica infection causes the yersiniosis disease, which is an animal-borne disease occurring in humans, as well as in a various groups of animals such as cattle, deer, pigs, and birds. Yersinia enterocolitica is a heterogeneous group of strains, which are conventionally classified by bio-typing into six bio-groups on the basis of phenotypic characteristics, and by serotyping into more than 57 “O” serogroups, on the basis of their O (lipopolysaccharide or LPS) surface antigen. Five of the six biogroups (1B and 2–5) are considered as pathogens. Nevertheless, only a few of these serogroups have been linked with disease in either humans or animals. Strains which belong to serogroups O:3 (biogroup 4), O:5,27 (biogroups 2 and 3), O:8 (biogroup 1B), and O:9 (biogroup 2) are most frequently isolated worldwide from human samples. Still, the main Y. enterocolitica serogroup in many European countries is serogroup O:3 followed by O:9, whereas the serogroup O:8 is mostly detected in the United States.

CD31 is a glycoprotein expressed on endothelial cells, platelets, macrophages and Kupffer cells, granulocytes, T / NK cells, lymphocytes, megakaryocytes, fibroblasts, osteoclasts, neutrophils. In humans, the gene encoding CD31 is found on chromosome 17.
CD31 is a cluster of differentiation molecule. It is also called PECAM-1 for platelet endothelial cell adhesion molecule. It plays a key role in removing aged neutrophils from the body. Both the neutrophil and the macrophage express CD31 on their membranes, and during the testing process, these CD31 molecules bind the two cells together. If the neutrophil is healthy, it will send a signal to the macrophage, and the CD31 molecules will detach.
CD31 is also expressed in certain tumors, including epithelioid hemangioendothelioma, epithelioid sarcoma-like hemangioendothelioma, other vascular tumors, histiocytic malignancies, and plasmacytomas. It is rarely found in some sarcomas and carcinomas.

Melanotan and Melanotan-II are both analogs of the peptide hormone alpha melanocyte stimulating hormone (a-MSH) that tend to induce skin tanning. Unlike Melanotan, Melanotan-II has the additional effect of increasing libido. Melanotan II has aphrodisiac properties.

Type 1 cystatins are also called stefins which function as intracellular thiol protease inhibitors. Cystatin-B protein is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins l, h and b. CSTB protein protects proteases leakage from lysosomes. Mutations in Stefin-B gene cause primary defects in patients with progressive myoclonic epilepsy (EPM1), a degenerative disease of the central nervous system. CSTB is overexpressed & elevated in the serum of HCC patients. Cystatin-B in vivo has a polymeric structure which is sensitive to the redox environment. Cystatin-B inhibits bone resorption by down-regulating intracellular cathepsin K activity despite increased osteoclast survival. Protein and mRNA levels of stefin B are significantly lower in atypical benign meningiomas. Stefins-A & Stefin-B which belong to the type-1 Cystatins, are up-regulated in lung tumours and thus able to counteract harmful tumour-associated proteolytic activity. Human stefin-A & Stef

HBsAg is the surface antigenof the Hepatitis-B-Virus (HBV). The capsidof a virus has different surface proteins from the rest of the virus. The antigen is a protein that binds specifically on one of these surface proteins. It is commonly referred to as the Australian Antigen.

CD4 is a cell-surface glycoprotein found on the mature helper T cells and immature thymocytes, as well as on monocytes and macrophages. (Some cytotoxic T cells have CD4 protein as well.) Normally, about 65% of T cells in the blood are CD4+ (have CD4 protein protruding from their membrane). A mature T cell with either have CD4 or CD8, but not both. During one stage of development T cells develop CD4 and CD8 receptors, but they eventually are differentiated in the thymus and become more specialized.

Fractalkine soluble form is chemotactic for t-cells and monocytes, but not for neutrophils. Fractalkine membrane-bound form promotes adhesion of those leukocytes to endothelial cells. Fractalkine regulates leukocyte adhesion and migration processes at the endothelium and binds to CX3CR1. Natural Human Fractalkine is produced as a long protein (373-amino acid) with an extended mucin-like stalk and a chemokine domain on top. The mucin-like stalk permits it to bind to the cell surface. Fractalkine gene is located on human chromosome 16 along with some CC chemokines known as CCL17 and CCL22.

KRT18 encodes the type I intermediate filament chain keratin 18. Keratin 18, together with its filament partner keratin 8, are perhaps the most commonly found members of the intermediate filament gene family. They are expressed in single layer epithelial tissues of the body. Mutations in this gene have been linked to cryptogenic cirrhosis. Two transcript variants encoding the same protein have been found for this gene.

Chemokine (C motif) ligand (XCL1) is a small cytokine belonging to the XC chemokine family that is also known as lymphotactin. It is found in high levels in spleen, thymus, intestine and peripheral blood leukocytes, and at lower levels in lung, prostate gland and ovary. Cellular sources for XCL1 include activated thymic and peripheral blood CD8+ T cells. This chemokine attracts T cells. In humans, XCL1 is closely related to another chemokine called XCL2, whose geneis found at the same locus on chromosome 1. XCL1 induces it chemotactic function by binding to a chemokine receptor called XCR1.

HCV is a small 50nm, enveloped, single-stranded, positive sense RNAvirus in the family Flaviviridae.
HCV has a high rate of replication with approximately one trillion particles produced each day in an infected individual. Due to lack of proofreading by the HCV RNA polymerase, the HCV has an exceptionally high mutation rate, a factor that may help it elude the host's immune response. Hepatitis C virus is classified into six genotypes(1-6) with several subtypes within each genotype. The preponderance and distribution of HCV genotypes varies globally. Genotype is clinically important in determining potential response to interferon-based therapy and the required duration of such therapy. Genotypes 1 and 4 are less responsive to interferon-based treatment than are the other genotypes (2, 3, 5 and 6).

Inhibins are dimeric peptide hormones produced by female ovarian granulose cells and male Sertoli cells as well as a variety of other tissues. Inhibins have two isoforms, A and B, with the same alpha subunit but different beta subunits. Inhibin A is a dimer of alpha and beta A subunits, inhibin B is a dimer of alpha and beta B subunits.
Inhibins are thought to inhibit the production of follicle-stimulating hormone (FSH) by the pituitary gland. In addition, Inhibins are also thought to play a role in the control of gametogenesis, and embryonic and fetal development.

Calumenin is a calcium-binding protein located in the endoplasmic reticulum (ER) and sarcoplasmic reticulum (SR) of mammalian tissues which plays a role in ER functions as protein folding and sorting. Calumenin belongs to a family of multiple EF-hand proteins (CERC) that include reticulocalbin, ERC-55, and Cab45 and the product of this gene. Calumenin binds 7 calcium ions having low affinity and takes part in such ER functions as protein folding and sorting.

Atosiban is the first oxytocin antagonist to be specifically developed for the treatment of preterm labor. Atosiban has a specific mode of action, inhibiting oxytocin-induced uterine contractions by blocking oxytocin receptors in the uterus. Extensive clinical investigations have shown Atosiban to be at least as effective as current tocolytic agents. In addition, due to its novel and specific mode of action, Atosiban has a markedly improved maternal side effects profile compared with conventional therapies.

IFIH1 is a DEAD box protein which is upregulated in response to treatment with beta-interferon and a protein kinase C-activating compound, mezerein. Irreversible reprogramming of melanomas can be attained by therapy with both these agents; treatment with either agent alone only achieves reversible differentiation. DEAD box proteins are implicated in several cellular processes involving alteration of RNA secondary structure such as translation initiation, nuclear and mitochondrial splicing, and ribosome and spliceosome assembly.

Dynactin 6, also known as DCTN6 is a member of the dynactin subunits 5/6 family. DCTN6 includes an RGD (Arg-Gly-Asp) motif in the N-terminal region, which confers adhesive properties to macromolecular proteins such as fibronectin. DCTN6 has a high degree of sequence resemblance with the mouse homolog, which has been found to participate in mitochondrial biogenesis. Moreover, the precise biological function of DCTN6 is unknown.

C17ORF49 is a component of chromatin complexes such as the MLL1/MLL and NURF complexes.

GDP-fucose protein O-fucosyltransferase 1 (POUFUT1), belongs to the glycosyltransferase O-Fuc family. POUFUT1 encodes a member of the glycosyltransferase O-Fuc family and Expressed mainly in pancreas, kidney, lung, heart, brain, liver, placenta and skeletal muscle.POUFUT1 adds O-fucose through an O-glycosidic linkage to Preserve serine or threonine residues in the epidermal growth factor-like repeats of a number of cell surface and emitted proteins. POUFUT1 is involved in ligand-induced receptor signaling. Alternative splicing of this gene results in 2 transcript variants encoding different isoforms.POFUT1 participates in Notch signaling, as Notch ligands can use as POFUT1 substrates.

Vitronectin (VTN) which is a part of the pexin family is a cell adhesion and spreading factor found in serum and tissues. VTN interacts with glycosaminoglycans and proteoglycans. VTN inhibits the membrane-damaging effect of the terminal cytolytic complement pathway and binds to numerous serpin serine protease inhibitors. Scientists have been noticed an over expression of VTN, integrins and plasminogen in migrating cells during wound healing.

Filamin binding LIM protein 1 (FBLIM1) plays a role as an anchoring site for cell-ECM adhesion proteins and filamin-containing actin filaments. FBLIM1 is involved in cell shape spreading and motility. FBLIM1 participates in the regulation of filamin-mediated cross-linking and stabilization of actin filaments. FBLIM1 promotes stimulation of integrins and regulates integrin-mediated cell-cell adhesion.

The La protein is a 47 kDa polypeptide that frequently acts as an autoantigen in systemic lupus erythematosus and Sjogren's syndrome patients. La is involved in various aspects of RNA metabolism, including binding and protecting 3-prime UUU(OH) elements of newly RNA polymerase III - transcribed RNA, processing 5-prime and 3-prime ends of pre-tRNA precursors, acting as an RNA chaperone, and binding viral RNAs linked to hepatitis C virus. It occurs in both the nucleus and the cytoplasm, where it assumes different roles. In the nucleus, La protein facilitates the production of tRNAs, acting as an RNA polymerase III (RNAP III) transcription factor by attaching to the U-rich 3'UTR of nascent transcripts, aiding in their folding and maturation. In the cytoplasm, La protein facilitates the translation of specific mRNAs, acting as a translation factor. As an RNA binding protein (RBP), La protein associates with subsets of mRNAs which contain a 5'-terminal oligopyrimidine (5'TOP) motif known to direct protein synthesis. The binding of La protein to particular classes of RNA molecules regulates their downstream processing, guards them from endonuclease digestion, and organizes their export from the nucleus. La/SS-B appears to be readily disposed to proteolysis, which results in many smaller (42kD, 320, and 270) nevertheless still immunoreactive polypeptides. La/SS-B antigen is strongly conserved across species. Anti-La/SS-B autoantibodies were originally found as precipitating autoantibodies in sera of Sjogren's Syndrome patients and referred to as SjT. Anti-La/SS-B precipitins are most frequently found in Sjogren's Syndrome, Systemic Lupus Erythematosus (SLE) and Subacute Cutaneous Lupus. Also, there seems to be a correlation between anti-La/SS-B and the absence of nephritis in SLE patients.

KRT18 encodes the type I intermediate filament chain keratin 18. Keratin 18, together with its filament partner keratin 8, are perhaps the most commonly found members of the intermediate filament gene family. They are expressed in single layer epithelial tissues of the body. Mutations in this gene have been linked to cryptogenic cirrhosis. Two transcript variants encoding the same protein have been found for this gene.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and subsequently, the atherosclerosis and abdominal aortic aneurysm.