Hepatitis C Genotypes and Subtypes Quiz
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Questions and Answers

What is the meaning of the term quasi-species in the context of viral infections?

  • A virus that has become less virulent over time
  • A swarm of genetically different viral variants in the same infected individual (correct)
  • A species of virus that is resistant to all known drugs
  • A virus that has mutated to infect a different host species

    • What is the most error-prone viral replicative enzyme?

  • Protease of HIV
  • Reverse transcriptase of HBV and retroviruses (correct)
  • RNA polymerase of influenza virus
  • DNA polymerase of herpesviruses

    • What can stabilize a genetic change in a viral population?

  • Vaccination
  • Environmental factors
  • Random fluctuations or a selective advantage (correct)
  • Antibiotics

    • What is the unique strategy used by HBV for replication?

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

    Which HIV genome region is the most prone to variation?

    <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 drug can work as monotherapy against HBV but not against HIV?

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

    What is the rate of mutations introduced in HBV genome by Reverse Transcriptase?

    <p>1 mutation / 105 nucleotide</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

    What is the effect of deletions and stop codons in the S antigen?

    <p>They induce an oxidative stress favoring the neoplastic transformation of hepatocytes.</p> Signup and view all the answers

    What is the correlation between deletions in pre-S regions and liver cancer risk?

    <p>The detection of deletions in pre-S regions correlates with increased risk of liver cancer.</p> Signup and view all the answers

    What is the effect of the lamivudine resistance mutations M204V+L180M+V173L in RT on HBsAg?

    <p>They strongly reduce the binding affinity with neutralizing antibodies including those induced by the vaccine.</p> Signup and view all the answers

    What is the efficacy of antivirals and vaccine against HBV?

    <p>High efficacy of antivirals, excellent vaccine.</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 important baseline predictor for response to Peg-IFN + Ribavirin Combination Therapy for Hepatitis C Virus?

    <p>HCV genotype</p> Signup and view all the answers

    What is the immediate precursor of HIV-1?

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

    What is the mechanism responsible for the great genetic diversity of HIV?

    <p>High error rate of transcription by RT enzyme, recombination during viral DNA synthesis, high daily rate of viral production, rapid selection of species under immune and pharmacological pressure</p> Signup and view all the answers

    What is viral recombination?

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

    What is the unique feature of recombination between the host cell genome and the genome of retroviruses?

    <p>The acquisition of cellular genes by viral genomes</p> Signup and view all the answers

    Why is HCV characterized by a high degree of genetic variability?

    <p>Its polymerase lacks the proofreading-function</p> Signup and view all the answers

    What is the concept of quasispecies in the context of viral infections?

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

    How does recombination occur in RNA viruses?

    <p>During replication, when the viral enzyme can jump from one template strand to another, dragging the chain of newly synthesized one and with the generation of an hybrid polynucleotide strand</p> Signup and view all the answers

    What is the estimated percentage of HIV isolates that represent recombinants between different subtypes?

    <p>Over 20%</p> Signup and view all the answers

    Which genotype of Hepatitis C Virus is the most efficient 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 for Hepatitis C Virus?

    <p>HCV 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 the immediate precursor of HIV-1?

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

    What is the unique feature of HBV genome organization?

    <p>It contains all the information necessary for its life cycle</p> Signup and view all the answers

    Which type of mutations in HIV-1 RT make the virus resistant to almost all NNRTIs?

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

    What is the rate of mutations introduced in HBV genome by Reverse Transcriptase?

    <p>1 mutation / 105 nucleotide</p> Signup and view all the answers

    Which HIV genome region is the most prone to variation?

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

    What is the most error-prone viral replicative enzyme?

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

    What is the term used to describe the presence of genetically different viral variants in the same infected individual for some viruses like HIV and HCV?

    <p>Quasi-species</p> Signup and view all the answers

    What is the most error-prone viral replicative enzyme?

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

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

    <p>Point mutations and recombination</p> Signup and view all the answers

    What is the concept derived from the observation that, in an individual infected for a long time, there is a continued evolution of the virus, as a result of spontaneous mutations and selective pressures exerted by host’s immunity and drug therapy?

    <p>Quasi-species</p> Signup and view all the answers

    What is the frequency of spontaneous mutations introduced in HBV genome by Reverse Transcriptase per nucleotide per replication cycle?

    <p>10000</p> Signup and view all the answers

    What is antigenic drift?

    <p>A gradual and continuous antigenic variation</p> Signup and view all the answers

    What is antigenic shift?

    <p>A sudden change in antigenic properties due to genetic reassortment</p> Signup and view all the answers

    Which viruses are subject to antigenic drift?

    <p>Influenza virus, HIV, HBV, and HCV</p> Signup and view all the answers

    What is the difference between antigenic drift and antigenic shift?

    <p>Antigenic drift is due to extended changes in antigenic properties, while antigenic shift refers to a gradual and continuous antigenic variation</p> Signup and view all the answers

    What is the significance of antigenic shift in the epidemiology of influenza viruses?

    <p>It can infect hosts already infected with the parental virus, leading to pandemic infections</p> Signup and view all the answers

    What is the practical implication of viral evolution?

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

    What is the effect of deletions and stop codons in the S antigen?

    <p>They can induce an oxidative stress thus favoring the neoplastic transformation of the hepatocytes.</p> Signup and view all the answers

    What is the correlation between deletions in pre-S regions and liver cancer risk?

    <p>The detection of deletions in pre-S regions correlates with increased risk of liver cancer.</p> Signup and view all the answers

    What is the efficacy of antivirals and vaccine against HBV?

    <p>High efficacy of antivirals, excellent vaccine.</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 effect of the lamivudine resistance mutations M204V+L180M+V173L in RT on HBsAg?

    <p>They strongly reduce the binding affinity with neutralizing antibodies including those induced by the vaccine.</p> Signup and view all the answers

    What is the unique feature of recombination between the host cell genome and the genome of retroviruses?

    <p>Acquisition of cellular genes by viral genomes</p> Signup and view all the answers

    What is the concept of quasispecies in the context of viral infections?

    <p>A population of viruses with a high degree of variability</p> Signup and view all the answers

    Why is HCV characterized by a high degree of genetic variability?

    <p>Its polymerase lacks the proofreading-function</p> Signup and view all the answers

    What is the frequency of recombination in those viruses in which the exchange of the template strand is a normal event in the process of synthesis of the viral genome?

    <blockquote> <p>20% of isolates</p> </blockquote> Signup and view all the answers

    What is the difference between antigenic drift and antigenic shift?

    <p>Antigenic drift is a continuous, slight seasonal variation of the external glycoproteins, while antigenic shift is due to extended changes in antigenic properties.</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 the significance of antigenic shift in the epidemiology of influenza viruses type A?

    <p>It can lead to pandemic infections.</p> Signup and view all the answers

    Which viruses have a relatively low mutation rate similar to that observed in cellular organisms?

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

    What is the reason for the genetic stability of DNA viruses?

    <p>They are not subject to antigenic shift.</p> Signup and view all the answers

    What is the term used to describe the presence of genetically different viral variants in the same infected individual for some viruses like HIV and HCV?

    <p>Viral quasispecies</p> Signup and view all the answers

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

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

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

    <p>HCV genotype</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 is the estimated percentage of HIV isolates that represent recombinants between different subtypes?

    <blockquote> <p>20%</p> </blockquote> Signup and view all the answers

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

    <p>Recombination and acquiring mutations</p> Signup and view all the answers

    What is the immediate precursor of HIV-1?

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

    What is the concept derived from the observation that, in an individual infected for a long time, there is a continued evolution of the virus, as a result of spontaneous mutations and selective pressures exerted by host’s immunity and drug therapy?

    <p>Viral quasispecies</p> Signup and view all the answers

    What is the unique feature of recombination between the host cell genome and the genome of retroviruses?

    <p>It is responsible for the great genetic diversity of HIV</p> Signup and view all the answers

    What is the unique mechanism responsible for the genetic diversity of HIV?

    <p>High error rate of transcription and lack of proofreading function by RT enzyme</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

    Why is HCV characterized by a high degree of genetic variability?

    <p>Its polymerase lacks the proofreading-function</p> Signup and view all the answers

    What is the term used to describe the high degree of variability of HCV at the patient level?

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

    What is the unique feature of recombination between the host cell genome and the genome of retroviruses?

    <p>Acquisition of cellular genes by viral genomes</p> Signup and view all the answers

    What is the effect of HCV polymerase lacking the proofreading-function?

    <p>High rate of mutations during replication</p> Signup and view all the answers

    What is the effect of lamivudine resistance mutations M204V+L180M+V173L in RT and I195M+E164D in HBsAg?

    <p>They strongly reduce the binding affinity with neutralizing antibodies</p> Signup and view all the answers

    What is the practical implication of genetic variability in S gene of HBV?

    <p>It can modulate HBV oncogenic potential</p> Signup and view all the answers

    What is the correlation between deletions in pre-S regions and liver cancer risk?

    <p>Deletions in pre-S regions increase the risk of liver cancer</p> Signup and view all the answers

    What is the implication of viral evolution?

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

    What is the implication of high variability of viruses?

    <p>It requires drug combinations to be controlled</p> Signup and view all the answers

    What is the smallest known animal DNA virus?

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

    What is the unique replication strategy used by HBV?

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

    What is the mutation rate introduced by the Reverse Transcriptase in HBV genome?

    <p>1 mutation / 105 nucleotide</p> Signup and view all the answers

    What is the most error-prone viral replicative enzyme?

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

    What is the class of drugs that target the attachment of HIV to host cells?

    <p>Entry inhibitors</p> Signup and view all the answers

    What is the class of drugs that target the fusion of HIV with host cells?

    <p>Fusion inhibitors</p> Signup and view all the answers

    What is the class of drugs that target the integration of HIV DNA into host cell DNA?

    <p>Integrase inhibitors</p> Signup and view all the answers

    What is the class of drugs that target the reverse transcription of HIV RNA into DNA?

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

    What is the unique feature of HBV genome organization?

    <p>It contains all the information necessary for its life cycle</p> Signup and view all the answers

    What is the most error-prone viral replicative enzyme?

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

    Which class of drugs targets the fusion of HIV with host cells?

    <p>Entry inhibitors</p> Signup and view all the answers

    What is the correlation between deletions in pre-S regions and liver cancer risk?

    <p>There is a higher risk of liver cancer with pre-S deletions</p> Signup and view all the answers

    Which region of the HIV genome is the most prone to variation?

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

    What is the most prevalent genotype of Hepatitis C Virus in chronically infected patients worldwide?

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

    Which HCV genotype is significantly more prevalent among patients with liver cirrhosis and those with decompensated liver disease requiring liver transplantation?

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

    What is the estimated percentage of HIV isolates that represent recombinants between different subtypes?

    <p>20%</p> Signup and view all the answers

    What is the mechanism responsible for the great genetic diversity of HIV?

    <p>Recombination during viral DNA synthesis</p> Signup and view all the answers

    Which HCV genotype is the most efficient in driving steatosis?

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

    What is the concept of quasi-species in virology?

    <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 a viral population?

    <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 term used to describe the high degree of variability of HCV at the patient level?

    <p>Quasi-species</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

    What is the effect of deletions and stop codons in the S antigen?

    <p>They induce an oxidative stress favoring neoplastic transformation of hepatocytes.</p> Signup and view all the answers

    What is the relationship between lamivudine resistance mutations in RT and HBsAg?

    <p>The mutations strongly reduce the binding affinity with neutralizing antibodies including those induced by the vaccine.</p> Signup and view all the answers

    What is the correlation between deletions in pre-S regions and liver cancer risk?

    <p>The detection of deletions in pre-S regions correlates with increased risk of liver cancer.</p> Signup and view all the answers

    What is the effect of genetic variability in S gene of HBV?

    <p>It can modulate HBV oncogenic potential.</p> Signup and view all the answers

    What is antigenic drift?

    <p>A process of gradual antigenic variation in viruses, both spontaneous or induced by the host immune system</p> Signup and view all the answers

    What is antigenic shift?

    <p>A process of extended changes in antigenic properties following a genetic reassortment</p> Signup and view all the answers

    Which viruses are subject to antigenic drift?

    <p>Influenza virus, HIV, HBV, and HCV</p> Signup and view all the answers

    Which viruses are prone to antigenic shift?

    <p>Influenza viruses type A, that can infect both human and animal hosts</p> Signup and view all the answers

    What is the difference between antigenic drift and antigenic shift?

    <p>Antigenic drift is a continuous and gradual antigenic variation in viruses, both spontaneous or induced by the host immune system, while antigenic shift is a process of extended changes in antigenic properties following a genetic reassortment</p> Signup and view all the answers

    What is viral recombination?

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

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

    <p>Double passage by viral HCV polymerase to create a (+)RNA template for protein synthesis.</p> Signup and view all the answers

    What is the mechanism of recombination in RNA viruses?

    <p>Break and rejoin of homologous nucleic acid strands already synthesized.</p> Signup and view all the answers

    What is the concept of quasispecies in viral infections?

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

    What is the frequency of recombination in retroviruses?

    <blockquote> <p>20% of HIV isolates are recombinants between different subtypes, CRFs.</p> </blockquote> Signup and view all the answers

    What is the unique feature of HBV replication compared to other DNA viruses?

    <p>HBV uses Reverse Transcriptase for replication</p> Signup and view all the answers

    Which HIV genome region is the most prone to variation?

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

    Which class of drugs targets the fusion of HIV with host cells?

    <p>Fusion inhibitors</p> Signup and view all the answers

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

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

    What is the estimated number of HIV-1 Circulating Recombinant Forms described till date?

    <blockquote> <p>100</p> </blockquote> 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

    Which virus is the immediate precursor of HIV-1?

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

    What is the estimated percentage of HIV isolates that represent recombinants between different subtypes?

    <p>20%</p> Signup and view all the answers

    Which genotype of Hepatitis C Virus is the most frequent worldwide in chronically infected patients?

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

    Which viral replicative enzyme lacks proofreading function?

    <p>RT enzyme</p> Signup and view all the answers

    What is the term used to describe the presence of genetically different viral variants in the same infected individual for some viruses like HIV and HCV?

    <p>Quasi-species</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 is the mechanism responsible for the great genetic diversity of HIV?

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

    What is the unique feature of HBV genome organization?

    <p>It has a circular partially double-stranded DNA genome</p> Signup and view all the answers

    What is the correlation between deletions in pre-S regions and liver cancer risk?

    <p>Deletions in pre-S regions increase liver cancer risk</p> Signup and view all the answers

    What is the practical implication of genetic variability in the S gene of HBV?

    <p>It can induce oxidative stress and favor neoplastic transformation of hepatocytes.</p> Signup and view all the answers

    What is the effect of the M204V+L180M+V173L mutations in RT of HBV?

    <p>They correspond to I195M+E164D in the HBsAg, which strongly reduces binding affinity with neutralizing antibodies.</p> Signup and view all the answers

    What is the correlation between deletions in pre-S regions and liver cancer risk?

    <p>Deletions in pre-S regions correlate with increased risk of liver cancer.</p> Signup and view all the answers

    What can explain seasonal outbreaks, host change, and pandemics?

    <p>Viral evolution.</p> Signup and view all the answers

    What is the implication of viruses with high propensity to variability?

    <p>They require drug combinations to be controlled.</p> Signup and view all the answers

    What is the mutation rate of DNA viruses during replication?

    <p>1 mutation every 10^7 - 10^10 base-pair per replication cycle</p> Signup and view all the answers

    Which type of viruses are generally more genetically stable than RNA viruses?

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

    What is antigenic drift?

    <p>Gradual antigenic variation due to spontaneous or induced changes</p> Signup and view all the answers

    Which viruses are subject to antigenic drift?

    <p>Influenza virus, HIV, HBV, and HCV</p> Signup and view all the answers

    What is antigenic shift?

    <p>Gradual antigenic variation due to genetic reassortment</p> Signup and view all the answers

    Which type of viruses are prone to antigenic shift?

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

    What is viral recombination?

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

    Why is HCV characterized by a high degree of genetic variability?

    <p>Its polymerase lacks the proofreading-function</p> Signup and view all the answers

    What is the concept of quasispecies?

    <p>The presence of genetically different viral variants in the same infected individual for some viruses like HIV and HCV</p> Signup and view all the answers

    What is the difference between viral recombination in DNA and RNA viruses?

    <p>Recombination in RNA viruses involves the exchange of homologous nucleic acid strands, while in DNA viruses it occurs during replication</p> Signup and view all the answers

    What is the frequency of recombination in viruses?

    <p>It is high in those viruses in which the exchange of the template strand is a normal event in the process of synthesis of the viral genome</p> Signup and view all the answers

    What is the unique feature of HBV replication compared to other DNA viruses?

    <p>HBV uses reverse transcriptase for replication</p> Signup and view all the answers

    Which HIV genome region is the most variable?

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

    What is the class of drugs that target the integration of HIV DNA into host cell DNA?

    <p>Integrase inhibitors</p> Signup and view all the answers

    What is the rate of mutations introduced in HBV genome by Reverse Transcriptase?

    <p>1 mutation per 105 nucleotides</p> Signup and view all the answers

    What is the most common NNRTI-resistant mutation in HIV-1?

    <p>K103N</p> Signup and view all the answers

    What is antigenic drift?

    <p>A gradual and continuous change in antigenic properties due to spontaneous or immune-induced variation</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 sudden change in antigenic properties due to genetic reassortment</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

    What is the significance of antigenic shift in the epidemiology of influenza viruses?

    <p>It leads to pandemic infections</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 HCV genotype is significantly more prevalent among patients with liver cirrhosis and those with decompensated liver disease requiring liver transplantation?

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

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

    <p>HCV genotype</p> Signup and view all the answers

    What is the immediate precursor of HIV-1?

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

    What is the reason for the great genetic diversity of HIV?

    <p>Recombination during viral DNA synthesis</p> Signup and view all the answers

    What is the practical implication of genetic variability in the S gene of HBV?

    <p>It can modulate the oncogenic potential of HBV</p> Signup and view all the answers

    What can explain seasonal outbreaks, host change, and pandemics of viruses?

    <p>Viral evolution</p> Signup and view all the answers

    What is the implication of viruses with high propensity to variability?

    <p>They require drug combinations to be controlled</p> Signup and view all the answers

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

    <p>Increased risk of liver cancer</p> Signup and view all the answers

    What is the implication of the variability of viruses?

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

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

    <p>A group of genetically different viral variants in an 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

    How can viruses be genetically modified?

    <p>By acquiring mutations during the replication of viral genome</p> Signup and view all the answers

    What is the term used to describe the high degree of variability of some viruses at the patient level?

    <p>Quasi-species</p> Signup and view all the answers

    What is the effect of reverse transcriptase lacking proofreading function?

    <p>Increased frequency of spontaneous mutations</p> Signup and view all the answers

    What is viral recombination?

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

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

    <p>Daily generation of a huge number of mutations.</p> Signup and view all the answers

    In which type of viruses is the frequency of recombination high?

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

    What is the concept of quasispecies in relation to HCV?

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

    What is the mechanism of recombination in DNA viruses?

    <p>The break and rejoin of homologous nucleic acid strands already synthesized.</p> Signup and view all the answers

    What is the unique feature of HBV replication compared to other DNA viruses?

    <p>It uses the Reverse Transcriptase for replication</p> Signup and view all the answers

    Which class of drugs targets the attachment of HIV to host cells?

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

    What is the most error-prone viral replicative enzyme?

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

    Which genome region of HIV is the most prone to variation?

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

    Which virus has a DNA genome characterized by a high genetic variability, second only to RNA viruses like HIV and HCV?

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

    What is the most efficient genotype 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?

    <p>HCV genotype</p> Signup and view all the answers

    What is the estimated percentage of HIV isolates that represent recombinants between different subtypes?

    <p>20-25%</p> Signup and view all the answers

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

    <p>A group of viruses that are all different in their genetic makeup</p> Signup and view all the answers

    What is the most error-prone viral replicative enzyme?

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

    How can viruses be genetically modified?

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

    What is the term for the continued evolution of the virus in an individual infected for a long time?

    <p>Quasi-species</p> Signup and view all the answers

    Which viruses have the concept of quasi-species been developed for?

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

    What is the difference between antigenic drift and antigenic shift in viruses?

    <p>Antigenic drift is due to gradual antigenic variation, while antigenic shift is due to genetic reassortment.</p> Signup and view all the answers

    Which viruses are subject to antigenic drift?

    <p>Influenza virus, HIV, HBV, and HCV</p> Signup and view all the answers

    What is the role of genetic reassortment in antigenic shift?

    <p>Genetic reassortment leads to completely different antigenic properties in the resulting virus.</p> Signup and view all the answers

    Which viruses are prone to antigenic shift?

    <p>Influenza viruses type A</p> Signup and view all the answers

    What is the effect of antigenic drift on influenza viruses?

    <p>It causes the virus to remain genetically stable.</p> Signup and view all the answers

    What is the effect of deletions and stop codons in the S antigen of HBV?

    <p>They induce oxidative stress and favor neoplastic transformation of hepatocytes</p> Signup and view all the answers

    What is the correlation between deletions in pre-S regions and liver cancer risk?

    <p>Deletions in pre-S regions increase the risk of liver cancer</p> Signup and view all the answers

    What is the practical implication of genetic variability in viruses?

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

    What is the effect of lamivudine resistance mutations M204V+L180M+V173L in RT on HBsAg?

    <p>They increase the binding affinity with neutralizing antibodies</p> Signup and view all the answers

    What is the implication of viral evolution?

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

    What is the unique feature of HBV genome organization?

    <p>It has a circular DNA genome</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 mechanism of recombination in DNA viruses?

    <p>Break and rejoin of homologous nucleic acid strands already synthesized</p> Signup and view all the answers

    What is the term used to describe the presence of genetically different viral variants in the same infected individual for some viruses like HIV and HCV?

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

    What is the mechanism responsible for the great genetic diversity of HIV?

    <p>Viral recombination</p> Signup and view all the answers

    Why is HCV characterized by a degree of genetic variability?

    <p>Its polymerase lacks the proofreading-function</p> Signup and view all the answers

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