viral

(noun)

A video, image or text spread by "word of mouth" on the internet or by e-mail for humorous, political or marketing purposes.

Related Terms

Examples of viral in the following topics:

  • Attachment and Entry of Herpes Simplex

    • Herpes simplex virus attaches to a host's cells with viral envelope glycoproteins, which then allows entry of the viral capsid into the host cell.
    • Finally, a stable entry pore is formed through which the viral envelope contents are introduced to the host cell .
    • The genome encodes for 11 different glycoproteins, four of which, gB, gC, gD and gH, are involved in viral attachment.
    • Afterward, gB interaction with the gH/gL complex creates an entry pore for the viral capsid.
    • Following attachment, the viral envelope fuses with the host cell membrane and the viral capsid gains entry into the cell.

  • Vaccines and Anti-Viral Drugs for Treatment

    • Vaccines and anti-viral drugs can be used to inhibit the virus and reduce symptoms in individuals suffering from viral infections.
    • In some cases, vaccines can be used to treat an active viral infection.
    • (a) Tamiflu inhibits a viral enzyme called neuraminidase (NA) found in the influenza viral envelope.
    • (b) Neuraminidase cleaves the connection between viral hemagglutinin (HA), also found in the viral envelope, and glycoproteins on the host cell surface.
    • Viral contents are released into the cell where viral enzymes convert the single-stranded RNA genome into DNA and incorporate it into the host genome.

  • Replication of Herpes Simplex Virus

    • On entering the cell, an α-TIF protein joins the viral particle and aids in immediate-early transcription.
    • The virion host shutoff protein (VHS or UL41) is very important to viral replication.
    • This enzyme shuts off protein synthesis in the host, degrades host mRNA, helps in viral replication, and regulates gene expression of viral proteins.
    • The viral genome immediately travels to the nucleus but the VHS protein remains in the cytoplasm.
    • An enzyme shuts off protein synthesis in the host, degrades host mRNA, helps in viral replication, and regulates gene expression of viral proteins.

  • Viral Replication and Gene Expression

    • Replication of viruses primarily involves the multiplication of the viral genome.
    • Replication also involves synthesis of viral messenger RNA (mRNA) from "early" genes (with exceptions for positive sense RNA viruses), viral protein synthesis, possible assembly of viral proteins, then viral genome replication mediated by early or regulatory protein expression.
    • Viral replication usually takes place in the cytoplasm .
    • Uncoating of the viral RNA is mediated by receptor-dependent destabilization of the virus capsid (2).
    • Cleavage of the viral protein VPg is performed by a cellular phosphodiesterase, and translation of the viral RNA occurs by a cap-independent (IRES-mediated) mechanism (3).

  • General Features of Virus Replication

    • Viruses must first penetrate and enter the cell before viral replication can occur.
    • This is often called viral entry.
    • Uncoating is a process in which the viral capsid is removed: This may be by degradation by viral or host enzymes or by simple dissociation.
    • This is accomplished through synthesis of viral messenger RNA (mRNA) from "early" genes (with exceptions for positive sense RNA viruses), viral protein synthesis, possible assembly of viral proteins, then viral genome replication mediated by early or regulatory protein expression.
    • Whenever the host divides, the viral genome is also replicated.

  • Steps of Virus Infections

    • Viral infection involves the incorporation of viral DNA into a host cell, replication of that material, and the release of the new viruses.
    • Once inside the cell, the viral capsid is degraded and the viral nucleic acid is released, which then becomes available for replication and transcription.
    • The replication mechanism depends on the viral genome.
    • The viral mRNA directs the host cell to synthesize viral enzymes and capsid proteins, and to assemble new virions.
    • If a host cell does not provide the enzymes necessary for viral replication, viral genes supply the information to direct synthesis of the missing proteins.

  • Virus Attachment and Genome Entry

    • Attachment is a specific binding between viral capsid proteins and specific receptors on the host cellular surface.
    • Viral populations do not grow through cell division, because they are acellular.
    • Attachment is a specific binding between viral capsid proteins and specific receptors on the host cellular surface.
    • Attachment to the receptor can induce the viral envelope protein to undergo changes that results in the fusion of viral and cellular membranes, or changes of non-enveloped virus surface proteins that allow the virus to enter.
    • This is often called "viral entry. " The infection of plant and fungal cells is different from that of animal cells.

  • Viral Genomes

    • The viral genome is the complete genetic complement contained in a DNA or RNA molecule in a virus.
    • Viral diseases have an enormous impact on human health worldwide.
    • An enormous variety of genomic structures can be seen among viral species; as a group, they contain more structural genomic diversity than plants, animals, archaea, or bacteria.
    • Viral genomes are circular, as in the polyomaviruses, or linear, as in the adenoviruses .
    • A viral genome, irrespective of nucleic acid type, is almost always either single-stranded or double-stranded.

  • Replicative Cycle of Influenza A

    • Delivering the genome to a site where it can produce new copies of viral proteins and RNA
    • The hemagglutinin protein fuses the viral envelope with the vacuole's membrane.
    • The M2 ion channel allows protons to move through the viral envelope and acidify the core of the virus, which causes the core to dissemble and release the viral RNA and core proteins.
    • Newly synthesized viral proteins are either secreted through the Golgi apparatus onto the cell surface (in the case of neuraminidase and hemagglutinin, Step 5b) or transported back into the nucleus to bind vRNA and form new viral genome particles (Step 5a).
    • The vRNA and viral core proteins leave the nucleus and enter this membrane protrusion (Step 6).

  • Classic Viral Hemorrhagic Fevers

    • Viral hemorrhagic fevers (VHFs) are a group of illnesses that are caused by several distinct families of RNA viruses.
    • The viral hemorrhagic (or haemorrhagic) fevers (VHFs) are a diverse group of animal and human illnesses that may be caused by five distinct families of RNA viruses: the families Arenaviridae, Filoviridae, Bunyaviridae, Flaviviridae, and Rhabdoviridae.
    • Ebola has five viral subtypes including Zaire, Sudan, Bundibugyo, Tai Forest (formerly Ivory Coast), and Reston.
    • For most viral hemorrhagic fevers, there is no effective treatment other than supportive care.
    • List the types, symptoms and routes of transmission for viral hemorrhagic fevers