Slow Viruses

Definition

Slow viruses are a class of viruses that cause chronic, progressive diseases in the nervous system. Unlike acute viral infections, slow viruses have an extremely long incubation period, often taking years or even decades to produce symptoms and cause significant damage to the brain and other nervous system structures.

5 Must Know Facts For Your Next Test

1. Slow viruses are distinguished by their extremely long incubation periods, often taking years or even decades to cause symptoms and significant neurological damage.
2. The slow, progressive nature of these viral infections is due to their ability to persist in the host's cells, evading the immune system and gradually accumulating damage over time.
3. Slow viruses primarily target the central nervous system, leading to a range of neurological symptoms, including cognitive decline, motor impairment, and ultimately, death.
4. Subacute sclerosing panencephalitis (SSPE) is a rare, fatal neurological disorder caused by a persistent measles virus infection, typically developing years after the initial measles infection.
5. Prion diseases, such as Creutzfeldt-Jakob disease (CJD) and Kuru, are a group of rare, neurodegenerative disorders caused by abnormally folded proteins called prions, which can induce other normal proteins to misfold and aggregate, leading to progressive neuronal damage.

Review Questions

• Explain the key features that distinguish slow viruses from other types of viral infections.
  • The defining features of slow viruses are their extremely long incubation periods and their ability to persist in the host's cells, often for years or even decades, before causing significant neurological damage. Unlike acute viral infections that produce rapid and severe symptoms, slow viruses gradually accumulate damage over time, leading to a slow, progressive course of disease. This persistent nature allows slow viruses to evade the host's immune system and continue to replicate and spread within the central nervous system, ultimately resulting in the development of debilitating neurological symptoms.
• Describe the primary targets and effects of slow viruses on the nervous system.
  • Slow viruses primarily target the central nervous system, including the brain and spinal cord. As these viruses persist and replicate within the host's cells, they gradually cause neuronal damage and dysfunction, leading to a range of neurological symptoms. These can include cognitive decline, such as memory loss and dementia, motor impairment, such as tremors and loss of coordination, and other neurological deficits. The progressive nature of slow viral infections often results in the eventual deterioration of the affected individual's neurological functions, ultimately leading to death in many cases.
• Analyze the role of prions in the development of certain slow viral diseases, and explain how they contribute to the pathogenesis of these disorders.
  • Prion diseases, such as Creutzfeldt-Jakob disease (CJD) and Kuru, are a unique group of slow viral diseases that are caused by abnormally folded proteins called prions, rather than traditional viral particles. These misfolded prion proteins can induce other normal proteins to misfold and aggregate, leading to a cascade of neuronal damage and degeneration. The self-propagating nature of prion diseases allows them to spread and persist within the nervous system, causing progressive neurological symptoms over an extended period of time. The ability of prions to evade the host's immune system and continue to induce protein misfolding contributes to the slow, relentless progression of these fatal neurodegenerative disorders, which are classified as a type of slow viral disease.

Related terms

Prion Diseases:

Prion diseases are a group of rare, fatal neurodegenerative disorders caused by abnormally folded proteins called prions, which can induce other normal proteins to misfold and aggregate, leading to progressive neuronal damage.

Subacute Sclerosing Panencephalitis (SSPE): SSPE is a rare, progressive neurological disorder caused by a persistent measles virus infection, typically developing years after the initial measles infection, and characterized by cognitive decline, seizures, and eventually death.

Kuru:

Kuru is a rare, neurodegenerative prion disease that was once prevalent among the Fore people of Papua New Guinea, who practiced ritual cannibalism, and is characterized by tremors, loss of coordination, and dementia.