Genomas Virales

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Questions and Answers

Qual es le principale differente inter antigenic shift e mutation?

Mutation es un alterazione major del sequencia antigenic.

Antigenic shift es un mutation minore in le sequencia antigenic.

Antigenic shift involve re-assortimento del genome o recombination inter stratos. (correct)

Antigenic shift non affetta le proteinas viral.

Como recombination pote influir le diversitate genetic del virus?

Per stabilir un genome constant sin alteration.

Per eliminar le mutaciones negative.

Per acquisser novas proteinas functionale alterate. (correct)

Per limitar le numero de proteinas available.

Qualcuno ha differenti caracteristicas de RNA e DNA in termino de structura de genoma?

RNA es tipicamente semplice e DNA es tipicamente doppio. (correct)

RNA ha un OH in 2’ ribose e DNA ha un H in 2’ ribose. (correct)

RNA usa thymine e DNA usa uracil.

RNA ha nucleos in principalement nucleare e DNA in cytoplasmatic.

In le context de virus RNA, quando es recombination plus frequente?

Quando le mechanism de replicar es discontinue. Signup and view all the answers

Quale de le sequente afirma le foi un impacte primari del vaccination in le evolution virale?

Le selection positiva es influentiate per le vaccinos. Signup and view all the answers

Quo significa quasispecies in le contexto de heterogeneitate genetic virale?

Multiple variantes genetic es presente in le population virale. Signup and view all the answers

Qual pote representar un obiettivo de viral mimicry?

Immuno-modulation per interager con receptores hospi. Signup and view all the answers

Qual es le resultado final del uso de decoys per disabilitar le sistema immune?

Inhibition del recognition immune del virus. Signup and view all the answers

Quale statement describe le relation inter le rati de mutation e le pression de selection in virus?

Le fitness viral determina le selection de mutations. Signup and view all the answers

Quale es un caracteriza distintiva del drift antigenic?

Drift antigenic es un processo stochastic. Signup and view all the answers

Qual es un exemplo de recombination non-homologous?

Incorporation de sequencias from un altere virus. Signup and view all the answers

Quale statement es correct concerning le estabilidad intrinseca de RNA e DNA?

Le stabilitate de RNA es inferior a DNA pro sua struttura. Signup and view all the answers

Qual es le vantaggio del grande size del genome viral double-stranded DNA?

Permitter le utilizo de decoys immune. Signup and view all the answers

Como le mutation rates pote influentiar le selection pressure super virus?

Mutation rates alte define le success de survival viral. Signup and view all the answers

Quale ha un effecto importante in le mutation rate de un virus?

Le selection positiva. Signup and view all the answers

Quale statement describe correcte le differente interġumente de RNA e DNA in contexto de polimerase fidelitate?

DNA presenta un error correction plus efficace. Signup and view all the answers

Quale de le sequente affirmationes se refera a mutationes de escape in SARS-CoV-2?

Mutation E484K emerge durante exposition a mAbs. Signup and view all the answers

Quid describe le structura del genoma de virus segmentate?

Distributo across duce o plus moleculas de RNA/DNA. Signup and view all the answers

Qual es le effecto del vaccination sur le evolution viral?

Vaccination crea pressiones selettive pro mutationes. Signup and view all the answers

Quo es un resultato de mutations in le spike protein del SARS-CoV-2?

Increased binding affinity pro le receptor ACE2. Signup and view all the answers

Qual mutation es associata con un aumento del infectivitate?

Δ69–70. Signup and view all the answers

Qual mutation conferisce resistencia contra mAbs?

S477G. Signup and view all the answers

Le quale de le sequente mutationes non es un mutation de escape identificat?

N148S. Signup and view all the answers

Qual es le consequence de insertions in le gene del NTD?

Abolishment of neutralization. Signup and view all the answers

Study Notes

Viral Genomes

Viruses can have either DNA or RNA genomes.
Different types of viruses have different genomic structures (single-stranded or double-stranded).
RNA viruses have faster evolution capacity, leading to rapid adaptation.
RNA viruses have plastic genomes that can increase coding capacity through segmentation and polyproteins.
dsDNA viruses have greater storage capacity which results in a broader protein arsenal.
dsDNA viruses are more stable and harder to detect in the nucleus, leading to persistent infections through latency.

Viral Origins

Early virology studies were linked to observations of plant diseases.
The infectious agent of tobacco mosaic disease was characterized by Martinus Beijerinck in 1899.
The pathogen was recognized as a virus, distinct from bacteria.
Viruses were also initially studied through observations of animal disorders.

The Puzzle of Virus Structure

Early research struggled with understanding the structural nature of viruses.
Stanley (1935) concluded that a virus was essentially protein in nature.
Bawden (1936) proposed the concept that viruses are ribonucleoprotein.

Peter Medawar on Viruses

Medawar described a simplistic but insightful quote expressing that a virus is malicious news wrapped up in a protein.

Viral Lifecycle

The fundamental aim of a virus is reproduction.
A general virus lifecycle includes attachment, entry, replication and expression of copies of the genome, assembly, and release.

Genomic Flavors of Viruses

Viruses exhibit diversity in their genomic configurations, categorized as single-stranded RNA, double-stranded RNA, single-stranded DNA, and double-stranded DNA.
This includes examples of various known viruses such as SARS-CoV-2, HIV, influenza, rabies, reovirus, rotavirus, parvovirus, hepatitis C, measles, Zika virus, poliovirus and the rift valley fever virus.

Viral Molecular Differences

RNA viruses typically use uracil.
RNA viruses typically consist of single-stranded genetic material.
RNA usually resides in the nucleus and/or cytoplasm.
RNA has an OH at the 2' ribose position.
DNA viruses typically use thymine
DNA viruses typically consist of double-stranded genetic material
DNA mainly resides in the nucleus.
DNA has an H at the 2' ribose position.

Biological Implications of Viruses

DNA is considered more stable than RNA.
RNA viruses have a higher mutation rate and are more susceptible to mutations, while DNA viruses have a lower mutation rate
RNA viruses have a much smaller genome size compared to DNA viruses
Different genome sizes confer varying mutation rates across numerous virus families.

Viral Heterogeneity

Viruses can exhibit genetic variability termed quasispecies.
Viral heterogenicity depends on mutation rate.
Viral fitness drives selection, with only beneficial mutations being retained.

Mutation Incidence and Antigenic Drift

Mutations may cause significant changes or antigenic drift in virus structure.
Antigenic drift is a stochastic process of accumulated small mutations, where significant advantages arise through selective pressure.
Prominent changes can occur in various parts of the virus such as the antibody scape and MHC scape.

Evolution of SARS-CoV-2 Spike

The N439K mutation enhances binding affinity for the ACE2 receptor.
The Y453F mutation increases ACE2 binding affinity.
Mutations can contribute to increased viral infectivity.
Key amino acid mutations can impact the receptor-binding domain (RBD), leading to decreased antibody effectiveness.

Segmented Viruses

Segmented viruses have genomes with genes distributed across multiple RNA or DNA molecules .
All segments must be incorporated into the viral particle for infectivity.
Examples include influenza virus and Rift Valley fever virus.

Genome Reassortment and Antigenic Shift

Genome reassortment is the mixing of genomic segments across different viral strains.
Antigenic shift is a significant change in viral antigen due to reassortment or inter-strain recombination.

Recombination

Recombination is the genetic exchange of material between viruses or with the host.
This process contributes to significant alterations in viral genes.
Recombination can cause significant changes, especially in RNA viruses where replication is discontinuous.

Genetic Storage Capacity

Genetic storage capacity is correlated with mutation rates in viruses.
Viruses that store genetic information in RNA have a higher mutation rate, while viruses with DNA have a lower mutation rate relative to genome size.

Viral Mimicry

Viruses employ strategies to mimic host cell receptors or inducers, manipulating the immune response by mimicking host factors.
Viruses may mimic or employ immuno-modulators to interfere with the host immune response

LIR1 Inhibitors

CMV UL18 interacts with natural killer receptors, blocking their activation, resulting in the loss of MHCs in infected cells preventing immune recognition.

Disabling the Immune System

DNA viruses frequently feature large genomes, enabling them to deploy various mechanisms designed to disable the host’s immune response. These may include decoys and disabling parts of the immune cell signaling pathways.

Absence of Antigens/Latency

DNA viruses can employ a latency mechanism, where the virus remains dormant and quiescent within the host cell.
Lack of viral antigens for a prolonged period can evade the host’s immune response.

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Description

Este quiz explora la struktur e origines de virus. Discurre sobre genomas viral e lor capacitate evolutive, como tamque lor storages de information. Preparea te pro un examen de virologia e apprende sobre virus RNA e DNA.