Decode the Science of DNA Virus Replication
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Questions and Answers

What is the main function of viral capsids?

  • To cause mutations in nucleic acids
  • To protect nucleic acids from physical and enzymatic damages (correct)
  • To mediate the binding and penetration of virus inside the host cell
  • To secrete cellular defense against infections

    • What is the pericapsid and which families of viruses have it?

  • It is composed of phospholipids and is present only in some families of viruses like orthomyxovirus and herpesvirus (correct)
  • It is composed of viral glycoproteins and all families of viruses have it
  • It is a viral protein and all families of viruses have it
  • It is a type of viral genome packaging found in all families of viruses

    • What is the role of capsid proteins of naked viruses?

  • To stimulate the host immune system
  • To protect nucleic acids from physical damages
  • To protect nucleic acids from enzymatic damages
  • To mediate the binding and penetration of virus inside the host cell (correct)

    • What is the function of RNA-dependent RNA polymerase in viral replication?

    <p>To synthesize mRNAs for translation</p> Signup and view all the answers

    What is the role of retroviral reverse transcriptase in viral replication?

    <p>To synthesize DNA from an RNA template</p> Signup and view all the answers

    Which type of RNA is used for the synthesis of new molecules of viral genome in riboviruses with double-stranded RNA?

    <p>(-) RNA strand</p> Signup and view all the answers

    What is the function of integrase in retroviral replication?

    <p>To catalyze the integration of viral DNA into host genome</p> Signup and view all the answers

    What is the only function of the genomic RNA in riboviruses with diploid genome?

    <p>To be used for the synthesis of double-stranded DNA</p> Signup and view all the answers

    What is the role of pericapsid in viral sensitivity to organic disinfectants?

    <p>Pericapsid dissolves lipids in the virus</p> Signup and view all the answers

    What is the difference between productive and abortive viral infection?

    <p>Productive infection leads to the production of viral particles, while abortive infection does not</p> Signup and view all the answers

    What is viral tropism?

    <p>The ability of the virus to recognize specific receptors and infect specific cell types</p> Signup and view all the answers

    What is the period between viral penetration and maturation called?

    <p>Period of eclipse</p> Signup and view all the answers

    What is the function of M2 protein in influenza virus?

    <p>Acts as an ion channel and causes acidification of endocytic vesicle containing the virus</p> Signup and view all the answers

    What is the replication strategy of Picornaviridae and Flaviviridae?

    <p>Their complete linear RNA genomes act as mRNA and is translated into a viral polyprotein which is subsequently cleaved into individual proteins by the viral protease.</p> Signup and view all the answers

    What is the function of RNA polymerase in + RNA viruses?

    <p>Synthesis of viral genome and mRNAs for structural proteins.</p> Signup and view all the answers

    Which virus group has only the translation of the 5' portion of viral genome?

    <p>Togaviruses, coronaviruses and caliciviruses (hepatitis E virus).</p> Signup and view all the answers

    What is the difference between the replication strategy of Parvovirus and Papovavirus?

    <p>Parvovirus can replicate only in cells that are in active proliferation, while Papovaviruses induce the progression of the cell cycle from the G1 to the S phase.</p> Signup and view all the answers

    What is the function of (-) RNA in riboviruses with negative RNA genome?

    <p>It cannot serve as mRNA.</p> Signup and view all the answers

    What is the replicative strategy for DNA viruses in the 1st group?

    <p>Viral gene expression occurs in the nucleus through RNA polymerase II</p> Signup and view all the answers

    What is the replicative strategy for DNA viruses in the 2nd group?

    <p>The entire replication cycle is completed in the cytoplasm</p> Signup and view all the answers

    What is the replicative strategy for DNA viruses in the 3rd group?

    <p>Viral gene expression requires synthesis of a complementary DNA strand</p> Signup and view all the answers

    What is the replicative strategy for DNA viruses in the 4th group?

    <p>Viral gene expression occurs in the nucleus through RNA polymerase II</p> Signup and view all the answers

    What do DNA viruses require to replicate their genome?

    <p>Their own DNA polymerase encoded in their genome</p> Signup and view all the answers

    What is the function of capsid proteins in naked viruses?

    <p>To mediate the binding and penetration of the virus inside the host cell</p> Signup and view all the answers

    What is the function of pericapsid in some families of viruses?

    <p>To act as virus receptor to target cells</p> Signup and view all the answers

    What is the role of nucleases and esterase in viral infections?

    <p>To cause enzymatic damages to nucleic acids</p> Signup and view all the answers

    What is the main function of viral capsids?

    <p>To protect nucleic acids from physical damages and enzymatic damages</p> Signup and view all the answers

    Which viral component is often the major antigen of naked viruses?

    <p>Capsid proteins</p> Signup and view all the answers

    What is the replicative strategy for DNA viruses in the 2nd group?

    <p>They complete the replication cycle in the cytoplasm</p> Signup and view all the answers

    What is the replicative strategy for DNA viruses in the 3rd group?

    <p>Their genome encodes for a DNA polymerase</p> Signup and view all the answers

    Which enzyme is used by HBV to synthesize its genome?

    <p>Reverse transcriptase</p> Signup and view all the answers

    How many replicative strategies do DNA viruses in the 1st group follow for the synthesis of mRNAs?

    <p>3</p> Signup and view all the answers

    Which virus group has a partially double-stranded DNA genome?

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

    What is the function of RNA-dependent RNA polymerase in viral replication?

    <p>To synthesize new molecules of viral genome from template RNAs</p> Signup and view all the answers

    Which type of RNA is used for the synthesis of new molecules of viral genome in retroviruses?

    <p>Genomic RNA</p> Signup and view all the answers

    What is the function of integrase in retroviral replication?

    <p>To integrate viral DNA into host genome</p> Signup and view all the answers

    What is the only function of the genomic RNA in riboviruses with diploid genome?

    <p>To be used for the double-stranded DNA synthesis</p> Signup and view all the answers

    What is the role of (+) RNA in retroviruses?

    <p>To serve as mRNAs for translation</p> Signup and view all the answers

    What is the period between viral penetration and maturation of viral progeny called?

    <p>Period of eclipse</p> Signup and view all the answers

    What is the function of M2 protein in influenza virus?

    <p>It acts as an ion channel and causes the acidification of endocytic vesicle containing the virus</p> Signup and view all the answers

    What is viral tropism?

    <p>The ability of the virus to recognize specific receptors and thus to infect specific cell types</p> Signup and view all the answers

    What is the role of pericapsid in viral sensitivity to organic disinfectants?

    <p>It accounts for the sensitivity of certain viruses to organic disinfectants</p> Signup and view all the answers

    What is the difference between productive and abortive viral infection?

    <p>Productive infection leads to the production of viral particles, while abortive infection does not</p> Signup and view all the answers

    What is the replicative strategy for riboviruses with negative RNA genome?

    <p>They synthesize new molecules of RNA with negative polarity</p> Signup and view all the answers

    Which virus group has complete linear RNA genomes that act as mRNA?

    <p>Picornaviridae and Flaviviridae</p> Signup and view all the answers

    What is the function of RNA-dependent RNA polymerase in + RNA viruses?

    <p>It synthesizes new molecules of RNA with positive polarity</p> Signup and view all the answers

    Which cells can Parvovirus replicate in?

    <p>Cells that are in active proliferation</p> Signup and view all the answers

    Which viruses have only the translation of the 5' portion of viral genome?

    <p>Togaviruses, Coronaviruses and Caliciviruses</p> Signup and view all the answers

    What is the main function of viral capsids?

    <p>To protect nucleic acids from physical and enzymatic damages</p> Signup and view all the answers

    What is the function of pericapsid in some families of viruses?

    <p>It is composed of phospholipids derived from cytoplasmic or intracellular membranes</p> Signup and view all the answers

    What is the role of capsid proteins of naked viruses?

    <p>To mediate the binding and penetration of the virus inside the host cell</p> Signup and view all the answers

    What can cause mutations in nucleic acids?

    <p>UV radiation</p> Signup and view all the answers

    What is the composition of pericapsid in some families of viruses?

    <p>Viral glycoproteins and phospholipids</p> Signup and view all the answers

    What is the period between viral penetration and maturation of viral progeny called?

    <p>Period of eclipse</p> Signup and view all the answers

    What is the function of M2 protein in influenza virus?

    <p>It acts as an ion channel and causes the acidification of endocytic vesicle containing the virus</p> Signup and view all the answers

    What is viral tropism?

    <p>The ability of the virus to recognize specific receptors and infect specific cell types</p> Signup and view all the answers

    What is the role of pericapsid in viral sensitivity to organic disinfectants?

    <p>It accounts for the sensitivity of certain viruses to organic disinfectants that can dissolve lipids</p> Signup and view all the answers

    What is the difference between productive and abortive viral infection?

    <p>Productive infection leads to the production of viral particles while abortive infection does not result in the production of viral particles</p> Signup and view all the answers

    What is the replicative strategy for DNA viruses in the 2nd group?

    <p>The entire replication cycle is completed in the cytoplasm</p> Signup and view all the answers

    Which group of DNA viruses requires the completion of the + strand by cellular enzymes before viral gene expression?

    <p>4th group</p> Signup and view all the answers

    What is the difference in the number of phases of viral gene expression between Herpesviruses/Adenoviruses and Papovaviruses?

    <p>Herpesviruses/Adenoviruses have 3 phases, Papovaviruses have 2 phases</p> Signup and view all the answers

    Which group of DNA viruses requires synthesis of the complementary DNA strand before gene expression by the cellular RNA polymerase II?

    <p>3rd group</p> Signup and view all the answers

    Which DNA virus group uses a RNA-dependent DNA polymerase to synthesize its genome?

    <p>4th group</p> Signup and view all the answers

    What type of cells can Parvovirus replicate in?

    <p>Cells in active proliferation</p> Signup and view all the answers

    Which group of viruses includes Picornaviridae and Flaviviridae?

    <p>Viruses with (+) sense RNA genomes</p> Signup and view all the answers

    What is the function of RNA-dependent RNA polymerase in (+) RNA viruses?

    <p>Synthesis of new molecules of RNA with positive polarity for viral genome and mRNAs</p> Signup and view all the answers

    Which type of RNA cannot serve as mRNA in riboviruses?

    <p>Single-stranded RNA with negative polarity</p> Signup and view all the answers

    What is the difference between the replication strategy of Parvovirus and Papovavirus?

    <p>Parvovirus induces the progression of the cell cycle from the G1 to the S phase, while Papovavirus can replicate only in cells that are in active proliferation</p> Signup and view all the answers

    What is the role of RNA-dependent RNA polymerase in viral replication?

    <p>It synthesizes both (+) and (-) RNA strands in riboviruses with double-stranded RNA</p> Signup and view all the answers

    Which enzyme is responsible for the synthesis of DNA from an RNA template in retroviruses?

    <p>Reverse transcriptase</p> Signup and view all the answers

    What is the only function of the genomic RNA in riboviruses with diploid genome?

    <p>To be used for the double stranded DNA synthesis</p> Signup and view all the answers

    What is the function of retroviral integrase?

    <p>It catalyzes the integration of viral DNA into the host genome</p> Signup and view all the answers

    Which viruses have a segmented double-stranded RNA?

    <p>Reoviruses and Rotaviruses</p> Signup and view all the answers

    What is the concept of quasi-species in viral populations?

    <p>The presence of genetically different viral variants in the same infected individual</p> Signup and view all the answers

    What is the most error-prone viral replicative enzyme?

    <p>Reverse transcriptase of HBV and retroviruses</p> Signup and view all the answers

    What can cause a genetic change to be stabilized in viral populations?

    <p>Both random fluctuations and selective advantage</p> Signup and view all the answers

    What are the ways in which viruses can be genetically modified?

    <p>Both acquiring mutations and re-assortment/recombination</p> Signup and view all the answers

    What is the most variable region of the HIV genome?

    <p>Env gene</p> Signup and view all the answers

    Which HIV-1 mutations make the virus resistant to almost all NNRTIs?

    <p>Y181C and Y181I</p> Signup and view all the answers

    Which virus has the smallest known animal DNA genome?

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

    Which group of drugs target almost every step of HIV replication?

    <p>Nucleos(t)ide reverse transcriptase inhibitors</p> Signup and view all the answers

    Which virus uses Reverse Transcriptase for its genome replication?

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

    What is the most frequent genotype of Hepatitis C Virus worldwide and in Europe?

    <p>Genotype 1</p> Signup and view all the answers

    Which genotype of Hepatitis C Virus is significantly more prevalent among patients with liver cirrhosis and those with decompensated liver disease requiring liver transplantation?

    <p>Genotype 1</p> Signup and view all the answers

    What is the most efficient genotype of Hepatitis C Virus in driving steatosis?

    <p>Genotype 3</p> Signup and view all the answers

    What is the most important baseline predictor for response to Peg-IFN + Ribavirin Combination Therapy in Hepatitis C Virus?

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

    What is the error rate of RT enzyme during transcription of HIV genome?

    <p>1:2,000-10,000 bases</p> Signup and view all the answers

    What is antigenic drift?

    <p>A gradual and continuous change in antigenic properties of a virus</p> Signup and view all the answers

    Which viruses are subject to antigenic drift?

    <p>RNA viruses</p> Signup and view all the answers

    What is antigenic shift?

    <p>A genetic reassortment that leads to new antigenic properties</p> Signup and view all the answers

    Which virus is a classic example of a virus subjected to antigenic drift?

    <p>Influenza virus</p> Signup and view all the answers

    Why is influenza virus prone to antigenic shift?

    <p>Because of its segmented genome</p> Signup and view all the answers

    What is the practical implication of viral evolution?

    <p>It can explain seasonal outbreaks, host change and pandemics</p> Signup and view all the answers

    How does genetic variability in S gene affect HBV oncogenic potential?

    <p>Deletions and stop codons can induce oxidative stress and favor neoplastic transformation of hepatocytes</p> Signup and view all the answers

    What is the implication of deletions in pre-S regions in HBV?

    <p>It correlates with increased risk of liver cancer</p> Signup and view all the answers

    What is the implication of viral variability in the efficacy of immunity?

    <p>It regulates the efficacy of natural and artificial immunity</p> Signup and view all the answers

    What is the implication of viral variability in the development of a vaccine?

    <p>It can be relatively easy in some cases, and very difficult (nearly impossible) in others</p> Signup and view all the answers

    What is viral recombination?

    <p>The exchange of homologous stretches of genetic material between two virus strains co-infecting the same cell</p> Signup and view all the answers

    What is the reason for HCV's high degree of genetic variability?

    <p>It lacks a proofreading function in its polymerase</p> Signup and view all the answers

    How do RNA viruses undergo recombination during replication?

    <p>By breaking and rejoining homologous nucleic acid strands already synthesized</p> Signup and view all the answers

    What is the concept of quasispecies?

    <p>The high degree of variability of a virus at the patient level</p> Signup and view all the answers

    What is the difference in recombination frequency between retroviruses and other viruses?

    <p>Retroviruses have a higher frequency of recombination</p> Signup and view all the answers

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