viral latency

Examples of viral latency in the following topics:

• Disease Development

  • During clinical latency, an infection is subclinical.
  • With respect to viral infections, in clinical latency the virus is actively replicating.
  • This is in contrast to viral latency, a form of dormancy in which the virus does not replicate.
  • Viral infections present with systemic symptoms.
  • Only a few viral infections are painful, like herpes.

• The Vocabulary Epidemiology

  • The latency period is the time between infection and the ability of the disease to spread to another person, which may precede, follow, or be simultaneous with the appearance of symptoms.
  • Some viruses also exhibit a dormant phase, called viral latency, in which the virus hides in the body in an inactive state.
  • Compare and contrast the following concepts: epidemic, endemic, pandemic; incidence vs prevalence; morbidity vs mortality; incubation, latency, acute, decline and convalescent periods

• Disease Severity and Duration

  • The latency period is the time between infection and the ability of the disease to spread to another person, which may precede, follow, or be simultaneous with the appearance of symptoms.
  • Some viruses also exhibit a dormant phase, called viral latency, in which the virus hides in the body in an inactive state.

• Double-Stranded DNA Viruses: Herpesviruses

  • Viral DNA then migrates to the cell nucleus where replication of viral DNA and transcription of viral genes occurs.
  • During symptomatic infection, infected cells transcribe lytic viral genes.
  • In some host cells, a small number of viral genes termed latency-associated transcripts accumulate instead.
  • While primary infection is often accompanied by a self-limited period of clinical illness, long-term latency is symptom-free.
  • Following activation, transcription of viral genes transitions from latency-associated transcripts to multiple lytic genes; these lead to enhanced replication and virus production.

• Treatment of Animal Viral Infections

  • In depth knowledge of the molecular basis of the viral cycle is needed to control viral pathogenesis and disease spreading.
  • Both viral and cellular proteins are required for replication and transcription.
  • Antiviral drugs are a class of medication used specifically for treating viral infections.
  • In addition to targeting viral infections directly, some therapeutics work by enhancing the immune responses necessary for viral clearance.
  • Elucidating the molecular and cellular biology of the virus-interferon interaction is key to understanding issues such as viral pathogenesis, latency, and the development of novel antivirals.

• Other Diseases and Epstein-Barr Virus

  • The viral envelope is embedded with glycoproteins essential to viral entry into the cell.
  • Once EBV enters the cell, the viral capsid dissolves and the viral genome is transported to the cell nucleus.
  • During lytic replication, viral DNA polymerase is responsible for copying the viral genome.
  • EBV can exhibit one of three latency programs: Latency I, Latency II, or Latency III.
  • Each latency program leads to the production of a limited, distinct set of viral proteins and viral RNAs.

• Replication of Herpes Simplex Virus

  • These stages of lytic infection, particularly late lytic, are distinct from the latency stage.
  • In the case of HSV-1, no protein products are detected during latency, whereas they are detected during the lytic cycle.
  • 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.
  • An enzyme shuts off protein synthesis in the host, degrades host mRNA, helps in viral replication, and regulates gene expression of viral proteins.

• Plant Virus Life Cycles

  • Attachment, or adsorption, occurs between the viral particle and the host cell membrane.
  • A hole forms in the cell membrane, then the virus particle or its genetic contents are released into the host cell, where viral reproduction may commence.
  • This is the final stage in the viral life cycle.
  • This hiding is deemed latency.

• 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.

• 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).