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The life cycle of Toxoplasma gondii has two 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.

Giardia intestinalis trophozoite known as Giardia lamblia is a flagellated parasite that found and replicates in the small intestine, resulting in giardiasis. Giardia lamblia parasite binds to the epithelium via a ventral adhesive disc, and replicates using binary fission. Giardia intestinalis trophozoite is bound to the lumen of the small intestine. Giardia lamblia are anaerobes while captivating the nutrients from the lumen of the small intestine. Among the major pathways in human infection are ingestion of untreated sewage, which is predominantly found in numerous developing countries, furthermore, infection of water is found in watersheds where massive grazing occurs.

Chlamydia is a common term for infection with any bacterium belonging to the phylum Chlamydiae. This term derives from the name of the bacterial genusChlamydiain the family Chlamydiaceae, order Chlamydiales, class and phylum Chlamydiae. There are two genera in Chlamydiaceae: Chlamydia and Chlamydophila. The genus Chlamydia includes three species: C. trachomatis, C. muridarum, and C. suis.

MV belongs to the Beta herpesvirinae subfamily of Herpesviridae which includes herpes simplex virustypes 1 and 2, varicella-zoster virus, and Epstein-Barrvirus. The herpesviruses share a characteristic ability to remain latentover long periods.CMV is a double-stranded linear DNA virus with 162 hexagonal protein capsomeres surrounded by a lipid membrane. CMV has the largest genome of the herpes viruses, ranging from 230-240 kilobase pairs. Human CMV is composed of unique and inverted repeats that include the existence of 4 genome isomers caused by inversion of L-S genome components (class E). Replication may be divided into immediate early, delayed early, and late gene expression based on time of synthesis after infection. The DNA is replicated by rolling circles. In vitro, CMV replicates in human fibroblasts.

Human immunodeficiency virus (HIV) is a retrovirusthat can lead to a condition in which the immune systembegins to fail, leading to opportunistic infections. HIV primarily infects vital cells in the humanimmune systemsuch as helper T cells(specifically CD4+ T cells), macrophagesand dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: firstly, direct viral killing of infected cells; secondly, increased rates of apoptosisin infected cells; and thirdly, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytesthat recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunityis lost, and the body becomes progressively more susceptible to opportunistic infections. HIV was classified as a member of the genus Lentivirus, part of the family of Retroviridae. Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period. Lentiviruses are transmitted as single-stranded, positive-sense, enveloped RNA viruses. Upon entry of the target cell, the viral RNA genomeis converted to double-stranded DNAby a virally encoded reverse transcriptasethat is present in the virus particle. This viral DNA is then integrated into the cellular DNA by a virally encoded integraseso that the genome can be transcribed. Once the virus has infected the cell, two pathways are possible: either the virus becomes latentand the infected cell continues to function, or the virus becomes active and replicates, and a large number of virus particles are liberated that can then infect other cells.

Flagellar calcium-binding protein (Protein FcaBP) is a protein which may be involved in swift motility of Trypanosoma, having an imperative role in flagellar structure and calcium metabolism, as it exhibits 4 EF-hand type (helix-loop-helix) structural domains, of which 3 may contain calcium-binding sites. Calcium has a vital role in the motility of Trypanosoma. The subcellular localization of Protein FcaBP is in the flagella of T. cruzi.

IL19 is a cytokine that belongs to the IL10 cytokine subfamily. IL-19 is found to be preferentially expressed in monocytes. It can bind the IL20 receptor complex and lead to the activation of the signal transducer and activator of transcription 3 (STAT3). A similar cytokine in mouse is reported to up-regulate the expression of IL6 and TNF-alpha and induce apoptosis, which suggests a role of this cytokine in inflammatory responses. Alternatively spliced transcript variants encoding the distinct isoforms have been described.

IL10 is a cytokine produced primarily by monocytes and to a lesser extent by lymphocytes. This cytokine has pleiotropic effects in immunoregulation and inflammation. It down-regulates the expression of Th1 cytokines, MHC class II Ags, and costimulatory molecules on macrophages. It also enhances B cell survival, proliferation, and antibody production. This cytokine can block NF-kappa B activity, and is involved in the regulation of the JAK-STAT signaling pathway. Knockout studies in mice suggested the function of this cytokine as an essential immunoregulator in the intestinal tract.

The protein encoded by this gene is a cytokine that acts as a growth and differentiation factor for both B cells and eosinophils. IL5is a main regulator of eosinopoiesis, eosinophil maturation and activation. The elevated production of IL5is reported to be related to asthma or hypereosinophilic syndromes. The receptor of IL5is a heterodimer, whose beta subunit is shared with the receptors for interleukine 3 (IL3) and colony stimulating factor 2 (CSF2/GM-CSF). IL5, together with those for interleukin 4 (IL4), interleukin 13 (IL13), and CSF2, form a cytokine gene cluster on chromosome 5. IL5, IL4, and IL13 are found to be regulated coordinately by long-range regulatory elements spread over 120 kilobases on chromosome 5q31.

TNFAIP8 which is a part of the TNFAIP8 family acts as a negative mediator of apoptosis and takes part in tumor progression. TNFAIP8 suppresses the TNF-mediated apoptosis by inhibiting caspase-8 activity but not the processing of procaspase-8, resulting in inhibition of BID cleavage and activation of caspase-3.

Hepatitis A Virus Cellular Receptor 2 (HAVCR2) is a member of the immunoglobulin superfamily. HACVR2 controls macrophage activation. HACVR2 inhibits T-helper type 1 lymphocyte (Th1)-mediated auto- and alloimmune responses and stimulates immunological tolerance.

MMAB protein catalyzes the last step in the conversion of vitamin B(12) into adenosylcobalamin (AdoCbl), a vitamin B12 containing coenzyme for methylmalonyl-CoA mutase(MCM). Decreased MMAB activity leads to the inherited disorder vitamin B12 dependent methylmalonic aciduria linked to the cblB complementation group.

Adenosine deaminase-like protein (ADAL) is a putative nucleoside deaminase. ADAL catalyzes the hydrolytic deamination of adenosine or some similar substrate and has a role in purine metabolism.

Major Histocompatibility Complex Class II DO Beta (HLA-DOB) is a part of the HLA class II beta chain paralogues. This class II beta chain is a heterodimer which is located in intracellular vesicles and consists of an alpha (DOA) and a beta chain (DOB), both anchored in the membrane. HLA-DOB which interacts with the HLA-DM molecule in B-cells is a significant modulator in the HLA class II restricted antigen presentation pathway. Class II molecules are expressed in antigen presenting cells such as B lymphocytes, dendritic cells and macrophages.

UBE2D4 is a member of the ubiquitin-conjugating enzyme family. Ubiquitin-conjugating enzymes (E2 enzymes or ubiquitin-carrier enzymes) execute the second step in the ubiquitination reaction which marks a protein for degradation using the proteasome. UBE2D4 receives ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. In vitro UBE2D4 can promote polyubiquitination using all 7 ubiquitin Lys residues, but usually selects 'Lys-11' and 'Lys-48'-linked polyubiquitination.

HCV is a small 50nm, enveloped, single-stranded, positive sense RNA virus 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).

Native human C8 is a glycosylated protein consist of 3 polypeptide chains: The alpha chain and the gamma chain are disulfide linkedwhereas, The beta chain is non-covalently bound to the a-g complex. C8 is necessary for formation of the membrane attack complex and is activated by binding on the cell membrane newly-formed C5b,C6,C7 complexes. Each pathway of complement activation generates proteolytic enzyme complexes which bind the target surface. These enzymes cleave a peptide bond in the larger alpha chain of C5 releasing C5a and activating C5b. Although C5b is unstable it remains bound to the activating complex for a few minutes during which it binds a single C6 from the surrounding fluid or it decays and is no longer capable of forming MAC.The C5b,6 complex may also remain connected to the C3/C5 convertase where the binding of a single C7 exposes a membrane-binding region and C5b,6,7 can enter into the bilipid layer of the target cell. Each C5b-7 complex can bind 1 molecule of C8 causing the complex to enter more firmly into the membrane.

IFN-alpha is produced by macrophages and has antiviral activities. Interferon stimulates the production of two enzymes: protein kinase and an oligoadenylate synthetase.

Human immunodeficiency virus (HIV) is a retrovirus that can lead to a condition in which the immune system begins to fail, leading to opportunistic infections. HIV primarily infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages and dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: firstly, direct viral killing of infected cells; secondly, increased rates of apoptosis in infected cells; and thirdly, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections. HIV was classified as a member of the genus Lentivirus, part of the family of Retroviridae. Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period. Lentiviruses are transmitted as single-stranded, positive-sense, enveloped RNA viruses. Upon entry of the target cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase that is present in the virus particle. This viral DNA is then integrated into the cellular DNA by a virally encoded integrase so that the genome can be transcribed. Once the virus has infected the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function, or the virus becomes active and replicates, and a large number of virus particles are liberated that can then infect other cells.

Leukemia Inhibitory Factor also called LIF is a lymphoid factor that promotes long-term maintenance of embryonic stem cells by suppressing spontaneous differentiation. Leukemia Inhibitory Factor has several functions such as cholinergic neuron differentiation, control of stem cell pluripotency, bone & fat metabolism, mitogenesis of factor dependent cell lines & promotion of megakaryocyte production in vivo. Human and mouse LIF exhibit a 78% identity in its amino acid sequence.

IFN-gamma produced by lymphocytes activated by specific antigens or mitogens.
IFN-gamma, in addition to having antiviral activity, has important immunoregulatory functions, it is a potent activator of macrophages, and has antiproliferative effects on transformed cells and it can potentiate the antiviral and antitumor effects of the type I IFNs.

Epidermal growth factor has a profound effect on the differentiation of specific cells in vivo and is a potent mitogenic factor for a variety of cultured cells of both ectodermal and mesodermal origin. The EGF precursor is believed to exist as a membrane-bound molecule which is proteolytically cleaved to generate the 53-amino acid peptide hormone that stimulates cells to divide. EGF stimulates the growth of various epidermal and epithelial tissues in vivo and in vitro and of some fibroblasts in cell culture. Long EGF is a recombinant analog of Human EGF developed as a replacement for use in therapeutic cell culture applications as a like-for-like supplement for Recombinant Human or native EGF. It includes the Human EGF amino acid sequence plus a 53 amino acid N-terminal extension peptide.

IL-7 is a cytokine important for B and T cell development. This cytokine and the hepatocyte growth factor (HGF) form a heterodimer that functions as a pre-pro-B cell growth-stimulating factor. This cytokine is found to be a cofactor for V(D)J rearrangement of the T cell receptor beta (TCRB) during early T cell development. This cytokine can be produced locally by intestinal epithelial and epithelial goblet cells, and may serve as a regulatory factor for intestinal mucosal lymphocytes. Knockout studies in mice suggested that this cytokine plays an essential role in lymphoid cell survival.

Interleukin-1b is produced by activated macrophages, IL-1B stimulates thymocyte proliferation by inducing il-2 release, b-cell maturation and proliferation, and fibroblast growth factor activity. IL1B proteins are involved in the inflammatory response, being identified as endogenous pyrogens, and are reported to stimulate the release of prostaglandin and collagenase from synovial cells.