Virus Life Cycle and PCR for Integrated DNA
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Questions and Answers

Qual es le prime passo del ciclo de vita del virus?

  • Fusione e entrata del virus
  • Binding (correct)
  • Assemblage e gemmazione
  • Transcription

    • La transcription viral occurre post le integrazione del DNA viral.

    True (A)

    Que es le resultato de la trascriptio et integration del DNA viral in un cellula?

    Produzione de DNA proviral.

    Le DNA viral es inserite in le genome del catto per le processo de ______.

    <p>integrazione</p> Signup and view all the answers

    Associa le seguenti partes del ciclo del vita del virus con le describtiones apropriatas:

    <p>Binding = Adhesione del virus a un cellula Fusion = Combinazione del membrane del virus e del cellula Translation = Produzione de proteinas viral Assembly = Formazione del virus completato</p> Signup and view all the answers

    Qual es le consequence de la activitation de un proto-oncogene per le virus?

    <p>Activitation aberrante de oncogene (D)</p> Signup and view all the answers

    Le integration de DNA viral nemo resulta in cancer automaticamente.

    <p>False (B)</p> Signup and view all the answers

    Quales son le dois mechanismos oncogenic que il es mentionate?

    <p>Activitation de proto-oncogene e inactivatie de gene suppressor de tumores.</p> Signup and view all the answers

    Quale protein es responsabile pro l'entrata del virus FeLV?

    <p>SU protein (C)</p> Signup and view all the answers

    FeLV-B es principalmente associato con l'immunosuppression.

    <p>False (B)</p> Signup and view all the answers

    Quale receptor es utilizzato da FeLV-C?

    <p>FLVCR1</p> Signup and view all the answers

    Infection con FeLV-C causa __________.

    <p>anemia</p> Signup and view all the answers

    Associa le sequentes varietates de FeLV con le lor descriptiones:

    <p>FeLV-A = Associato con immunosuppression FeLV-B = Associato con neoplasia FeLV-C = Associato con anemia</p> Signup and view all the answers

    Quale delle sequentes afferma un factore implicato in l'entrata de FeLV?

    <p>Co-Factor expressato in cellules lymphoide (D)</p> Signup and view all the answers

    Le polymerase virale es altamente precise durante le replication.

    <p>False (B)</p> Signup and view all the answers

    Quale es un effecto del FeLV-T-cell tropic?

    <p>Induce immunodeficiencia</p> Signup and view all the answers

    Qual virus necesita un 'helper' virus para infectar novas cellulas?

    <p>Oncogenic virus (C)</p> Signup and view all the answers

    Le polymerase viral (reverse transcriptase) es accurato durante le replication.

    <p>False (B)</p> Signup and view all the answers

    Quid significa LTR in le context de virus?

    <p>Long Terminal Repeat</p> Signup and view all the answers

    Le ____ virus forniresse proteins viral in trans pro rescatar le virus defective.

    <p>helper</p> Signup and view all the answers

    Que effecto ha le duplications interne LTR sur le patogenese?

    <p>Activation by alternate transcription factors (A)</p> Signup and view all the answers

    Le oncogenes pote esser inserite solmente in specific locations del genome retroviral.

    <p>False (B)</p> Signup and view all the answers

    Quas son le proteinas structural in le virus oncogenic?

    <p>SU &amp; TM</p> Signup and view all the answers

    Le ____ virus es associate con lymphomas thymic, un tipo de tumor T cell.

    <p>defective</p> Signup and view all the answers

    Associa le virus con su categorisation:

    <p>FeLV = Viral helper virus FeSV = Defective virus Oncogenic virus = Cancer related Asymptomatic cats = Normal condition</p> Signup and view all the answers

    Qual es le consequence de frequent mutations in le LTR e SU envelope protein?

    <p>Altered pathogenesis (D)</p> Signup and view all the answers

    Flashcards

    Virus Life Cycle (General)

    Le succession de stadias durante le evolution de un virus.

    Binding

    Le prime stadio in le ciclo vital de un virus, ubi le virus se liga a le cellula hospite.

    Reverse Transcription

    Le processo ubi le information genetic viral RNA es convertite in DNA.

    Integration

    Le insertion del DNA viral in le genome del cellula hospite.

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    Proviral DNA

    Le forma de DNA viral integrate in le genome del cellula hospite.

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    Oncogenic Mechanism 1 (Insertional Activation)

    Le activation de un gene cellular proto-oncogene per le insertion viral.

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    Oncogenic Mechanism 2 (Insertional Inactivation)

    Le inactivation de un gene suppressore de tumor per le insertion viral.

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    PCR Test

    Un methodo pro detectar le DNA viral integrate in le genome del animal.

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    Retroviral Oncogenes

    Retroviruses that can cause cancer by carrying oncogenes into new cells.

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    Viral Acquisition

    Retroviruses get oncogenes from cells, leading to rapid tumor development.

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    Helper Virus

    A virus that provides viral proteins to a defective virus.

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    Defective Virus

    A virus lacking complete viral genes for replication.

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    Viral Polymerase (Reverse Transcriptase)

    Enzyme that copies viral RNA into DNA. It is error prone.

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    LTR Duplication

    Repeated copies of LTR sequences in the viral genome.

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    Internal LTR Duplication

    Duplication of LTR regions within the same viral genome affecting the disease.

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    21 bp LTR Region

    A specific 21 base pair region in the LTR sequence.

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    Viral Pathogenesis

    Process by which a virus causes disease.

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    Viral Genome Change

    Changes induced in the virus genome, often resulting from errors in replication, duplication, or mutations

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    Viral Genomes Mutate During Replication

    Viral genomes frequently change during replication, often due to errors in their viral polymerase.

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    SU Protein and Entry

    The SU protein is vital for a virus's entry into cells by binding to cellular receptors, which is virus-specific.

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    FeLV Subgroup Viruses

    Different FeLV (Feline Leukemia Virus) subgroups utilize different cellular receptors for entering cells.

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    FeLV-C and Anemia

    FeLV-C infection disrupts the normal function of the FLVCR1 receptor (involved in heme export), causing depletion of erythrocyte precursors and leading to fatal anemia.

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    T-Cell-Tropic FeLV

    Certain FeLV types (T-cell-tropic) are characterized by unique entry requirements, needing a cofactor for cell entry and binding to similar receptors as FeLV-B.

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    Causes of FeLV Subgroups

    FeLV subgroups arise from recombination (e.g., FeLV-B) or mutations (e.g., FeLV-C) in the SU protein.

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    FeLV-A and Immunosuppression

    FeLV-A, the "street" virus, is predominantly associated with immunosuppression.

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    FeLV-B and Neoplasia

    FeLV-B is associated with neoplasia (cancer development).

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    Study Notes

    Virus Life Cycle

    • The virus initially binds to the host cell.
    • Fusion and virus entry occur subsequently.
    • Reverse transcription of viral RNA into viral DNA occurs.
    • Viral DNA integrates into the feline DNA.
    • Transcription and viral genome production follow integration.
    • The viral genome is translated then.
    • Assembly and budding of progeny viruses conclude the cycle.

    PCR Test for Integrated Viral DNA

    • Proviral DNA is viral DNA integrated into the cat's genome.
    • PCR can detect proviral DNA.
    • Primers 1 and 2 target specific regions (LTR, gag, pol, env) within the proviral DNA.
    • Amplifying the specific region confirms proviral DNA presence.

    Viral LTR Drives Expression of Viral Genes

    • Proviral DNA contains LTR sequences (long terminal repeats).
    • LTR acts as a promoter for viral genes.
    • Viral promoter activates transcription of various viral genes.
    • Viral genes encode proteins important for viral replication (capsid, replication enzymes, envelope).

    Oncogenic Mechanism 1: Viral Insertional Activation of a Cellular Proto-Oncogene

    • Normal gene expression, cellular promoter is off.
    • Provirus insertion can activate proto-oncogenes.
    • Aberrant expression of oncogene occurs.
    • Insertion may cause cellular promoter turning on.
    • Oncogenes contribute to unregulated cell growth.
    • Cancer formation is the result of this.

    Oncogenic Mechanism 2: Viral Insertional Inactivation of a Tumor Suppressor Gene

    • Normal gene expression, cellular promoter is off.
    • Tumor suppressors are inactivated by proviral insertion.
    • Inactivation causes loss of tumor suppressor function.
    • Insertion may cause cellular promoter turning on.
    • This deregulation of function can lead to cancer.

    Oncogenic Mechanism 3: Viral Acquisition of Cellular Oncogenes (Transduction)

    • Viruses can carry oncogenes from other sources.
    • Oncogenes can be inserted at random points in retroviral genomes.
    • Involves interaction of defective virus (FeSV) with helper virus (FeLV).
    • Helper virus provides viral proteins needed for the defective virus to replicate properly.

    Viral Genomes Also Change During Replication

    • Viral polymerase (reverse transcriptase) is prone to errors.
    • Frequent duplications and mutations in LTR and SU envelope proteins occur.
    • Errors result in altered pathogenesis.

    Internal LTR Duplications Impact Pathogenesis

    • Internal LTR (long terminal repeat) duplication patterns vary.
    • Duplication patterns associated with different pathologies.
    • Duplicated LTR region's associated with different cell types and diseases.
    • Variations are linked to altered pathogenesis.

    Viral Genomes Also Mutate During Replication

    • Viral polymerase (reverse transcriptase) has errors during replication.
    • Frequent mutations in LTR and SU protein.
    • Mutation consequences result in altered pathogenesis.

    SU Protein Responsible for Entry

    • Viruses utilize host cell proteins for entry.
    • Receptor use is virus-specific.
    • FeLV uses SU protein to bind host cell receptors specifically.

    Subgroup Viruses Use Different Cellular Receptors

    • FeLV subgroups arise from recombination and mutations.
    • Different FeLV subgroups, use distinct host receptors.
    • Receptor use influences pathogenesis.
    • Only some cells express the receptors.

    FeLV Types

    • FeLV-A: Associated with immunosuppression.
    • FeLV-B: Associated with neoplasia.
    • FeLV-C: Associated with anemia, linked to heme export receptor issues and depletion of erythroid precursors.

    Chronic FeLV-C Infection Causes Fatal Anemia

    • The receptor for FeLV-C is FLVCR1.
    • Normal function is heme export.
    • FeLV-C infection disrupts receptor function.
    • Results in erythrocyte precursor depletion.

    Infection with T-Cell-Tropic FeLV Induces Immunodeficiency (FeLV-FAIDS)

    • T-cell-tropic FeLV (mutation/recombination in SU protein)
    • Binds to receptors similar to FeLV-B but necessitates a co-factor for entry.
    • Co-factor expression is restricted to lymphoid cells.
    • T-cells perish after infection.

    FeLV Vaccines

    • Vaccines lessen progressive infections.
    • Available in whole killed, subunit, and recombinant canary pox vector formats.
    • Potential fibrosarcoma side effects are reduced by peripheral administration.
    • High-risk cats are vaccinated.

    Key Concepts

    • FeLV causes proliferative and degenerative illnesses.
    • FeLV molecular biology is relevant in pathogenesis.
    • Transmission happens through contact or biting.
    • Infected cats can have abortive, regressive, or progressive infections.
    • Vaccines reduce the probability of progressive diseases.
    • FeLV test types depend on the time period following infection.

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    Related Documents

    Feline Leukemia Virus (FeLV) PDF

    Description

    This quiz covers the life cycle of viruses, from binding to host cells to the assembly of progeny viruses. It also explores the detection of integrated viral DNA through PCR testing and the role of LTRs in driving the expression of viral genes. Test your understanding of these crucial concepts in virology.

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