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Chitodextrinase is a unique membrane-bound endoenzyme. The chitodextrinase enzyme cleaves soluble oligomers, but not chitin, to the di- and trisaccharides. Chitodextrinase is unable to solubilize chitin, but it can catalyze the hydrolysis of high to low molecular weight soluble chitin oligosaccharides.

HIV-1 and HIV-2 appear to package their RNA differently. HIV-1 binds to any appropriate RNA whereas HIV-2 preferentially binds to mRNA which creates the Gag protein itself. This means that HIV-1 is better able to mutate. HIV-2 is transmitted in the same ways as HIV-1: Through exposure to bodily fluids such as blood, semen, tears and vaginal fluids.
Immunodeficiency develops more slowly with HIV-2.
HIV-2 is less infectious in the early stages of the virus than with HIV-1.
The infectiousness of HIV-2 increases as the virus progresses.
Major differences include reduced pathogenicity of HIV-2 relative to HIV-1, enhanced immune control of HIV-2 infection and often some degree of CD4-independence. Despite considerable sequence and phenotypic differences between HIV-1 and 2 envelopes, structurally they are quite similar. Both membrane-anchored proteins eventually form the 6-helix bundles from the N-terminal and C-terminal regions of the ectodomain, which is common to many viral and cellular fusion proteins and which seems to drive fusion.
HIV-1 gp41 helical regions can form more stable 6-helix bundles than HIV-2 gp41 helical regions however HIV-2 fusion occurs at a lower threshold temperature (25°C), does not require Ca2+ in the medium, is insensitive to treatment of target cells with cytochalasin B, and is not affected by target membrane glycosphingolipid composition.

Shiga-like toxin (verotoxin) is a toxin produced by some strains of Escherichia coli. Shiga-like toxin is named for its similarity to the AB5-type Shiga toxin produced by the bacteria Shigella dysenteriae. There are two known types-SLT1 and SLT2. The Shiga-like toxin is linked with hemolytic-uremic syndrome. Shiga-like toxin requires highly specific receptors on the cells' surface in order to attach and enter the cell. Species such as cattle, swine, and deer which do not carry these receptors may harbor toxigenic bacteria without any ill effect, dropping them in their feces, from where they may be distributed to humans. Shiga Like Toxin-1 Subunit B has nontoxic action, it is the functional region which binds to the receptor. The Shiga Like Toxin-1 Subunit B can be useful in vaccine study, antibody test and other functional research.

HBsAg is the surface antigen of the Hepatitis-B-Virus (HBV). The capsid of 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. HBsAg is an important parameter to establish a diagnosis of hepatitis B disease in the clinic and to monitor antiviral treatment.

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.

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 (severe acute respiratory syndrome) is caused by a human coronavirus. Human coronaviruses are the major cause of upper respiratory tract illness, such as the common cold, in humans. 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 glycosilated spike protein (as well as the nucleocapsid protein) can be detected in infected cell culture supernatants with antisera from SARS patients.

Simian immunodeficiency virus, SIV, is a retrovirusthat is found in strains, having the HIV-1and HIV-2specific strains that infect humans. SIV strains may cause an AIDS-like immune deficiency known as SAIDS (simian acquired immunodeficiency syndrome) if they cross species boundaries. HIV-2 is more similar to SIV strains than to HIV-1, suggesting for the first time the simian origin of HIV. HIV-2 is derived from the SIV strain found in sooty mangabeys whereas HIV-1, the predominant virus found in humans, is derived from SIV strains infecting chimpanzees.

H1N1 is a subtype specie of Influenza A virus. H1N1 Influenza Virus has mutated into various strains such as the Spanish Flustrain, mild humanflu strains, endemic pigstrains, and various strains found in birds. The Influenza A Virus is a globular particle about 100nm in diameter, sheathed in a lipid bilayer derived from the plasma membrane of its host. Studded in the lipid bilayer are two integral membrane proteins some 500 molecules of hemagglutinin ("H") and some 100 molecules of neuraminidase ("N"). Within the lipid bilayer are 3000 molecules of matrix protein and 8 pieces of RNA. Each of the 8 RNA molecules is associated with many copies of a nucleoprotein, several molecules of the three subunits of its RNA polymerase some "non-structural" protein molecules of uncertain function.

H1N1 is a subtype specie of Influenza A virus. H1N1 Influenza Virus has mutated into various strains such as the Spanish Flustrain, mild humanflu strains, endemic pigstrains, and various strains found in birds. The Influenza A Virus is a globular particle about 100nm in diameter, sheathed in a lipid bilayer derived from the plasma membrane of its host. Studded in the lipid bilayer are two integral membrane proteins some 500 molecules of hemagglutinin ("H") and some 100 molecules of neuraminidase ("N"). Within the lipid bilayer are 3000 molecules of matrix protein and 8 pieces of RNA. Each of the 8 RNA molecules is associated with many copies of a nucleoprotein, several molecules of the three subunits of its RNA polymerase some "non-structural" protein molecules of uncertain function.

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 probably 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.

UGDH is part of the UDP-glucose/GDP-mannose dehydrogenase family and is a widely expressed enzyme localized in the liver. UGDH transfers UDP-glucose to UDP-glucuronate and thus takes part in the biosynthesis of glycosaminoglycans such as hyaluronan, chondroitin sulfate, and heparan sulfate. These glycosylated products are ordinary molecules of the extracellular matrix and participate in signal transduction, cell migration, and cancer growth and metastasis.

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.

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.

DBI, also known as Acyl-CoA-binding protein isoform 2, is a diazepam binding inhibitor, which is regulated by hormones. DBI participates in lipid metabolism and in the displacement of beta-carbolines & benzodiazepines, which modulate signal transduction at type A gamma-aminobutyric acid receptors located in brain synapses. Moreover, during adipocyte differentiation the expression of DBI is significantly induced. DBI preforms as an acyl-CoA pool former and regulates LCFA (long-chain fatty acids) metabolism in peripheral tissues.

Deoxyribose-phosphate aldolase (DERA) is a member of the deoC/fbaB aldolase protein family involved in the carbohydrate degradation pathway. DERA catalyzes the conversion of 2-deoxy-D-ribose 5-phosphate to D-glyceraldehyde 3-phosphate and an acetyldehyde.

Ectonucleoside Triphosphate Diphosphohydrolase 6 or ENTPD6 is an enzyme, akin to E-type nucleotidases. E-type nucleotidases, for instance CD39, are responsible for extracellular nucleotides catabolism. ENTPD6 has four apyrase-conserved areas like all to E-type nucleotidases. Rather spliced transcript agents that codes various isoforms were discovered for the DNA segment.

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.

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.

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.

Since April 2012, cases of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) have been identified in various countries. Coronaviruses are the cause of the common cold, SARS (severe acute respiratory syndrome) and other severe illnesses with high mortality rates, all are classified into coronavirus family. MERS-CoV is a new type of SARS found in the coronavirus family causing severe pneumonia with sudden and serious respiratory illness with high mortality rates as well. Since January 27th 2015, the WHO has reported 956 human cases, including 351 deaths. More cases of the new coronavirus strain are expected. Like in other coronaviruses, large surface spike glycoprotein is a central structural protein of this virus; it is located above the virion surface to bind and enter into the target cell. Spike protein has 2 domains- S1 and S2. The S1 domain is responsible for cellular tropism and interaction with target cell, while the S2 domain is responsible for membrane fusion. The C-terminal of S1 domain contains a receptor binding domain, and is also a potential target for vaccine development and an antigen for diagnosis.

Shiga-like toxin (verotoxin) is a toxin produced by some strains of Escherichia coli. Shiga-like toxin is named for its similarity to the AB5-type Shiga toxin produced by the bacteria Shigella dysenteriae. There are two known types-SLT1 and SLT2. The Shiga-like toxin is linked with hemolytic-uremic syndrome. Shiga-like toxin requires highly specific receptors on the cells'' surface in order to attach and enter the cell. Species such as cattle, swine, and deer which do not carry these receptors may harbor toxigenic bacteria without any ill effect, dropping them in their feces, from where they may be distributed to humans. Shiga Like Toxin-1 Subunit B has nontoxic action, it is the functional region which binds to the receptor. The Shiga Like Toxin-1 Subunit B can be useful in vaccine study, antibody test and other functional research.

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.

Noroviruses are categorized into two groups - group 1 and group 2. Norovirus is a widespread virus which can cause human gastroenteritis, an illness characterized with symptoms such as abdominal pain, diarrhea, vomiting and sickness. In America there are about 20 million causes of infection by Nororvirus, 800 ending in deaths. Worldwide, this virus infects around 267 million people and causes over 200,000 deaths per year. Even though having norovirus is unpleasant, it is seldom dangerous and typically ends in full recovery after few days. The cases resulting in deaths are primarily very young, elderly and immuno-suppressed individuals and people from less developed countries. Norovirus is extremely contagious and is spread from person to person, by infected food or water or polluted surfaces. Outbreaks usually happen from November to April, peaking in January.