MEDICAL MICROBIOLOGY, PAMB 650/720
Slow virus diseases of the central nervous system LECTURE: 79
Dr. Margaret Hunt
Murray et al., Microbiology, 5th Ed., Chapter 52 (polyomavirus section),
Chapter 59 (measles), Chapter 63 (rubella), Chapter 63 (prions)
Introduction to subacute/chronic diseases of the central nervous system due to viruses or
associated with prions. Properties of unconventional agents (prions) associated with subacute
diseases of the central nervous system and discussion of the diseases they cause.
Slow virus infections: term refers to the tempo of the DISEASE, not to the growth rate of the virus.
Such diseases have a prolonged incubation period (months or years), and a protracted,
progressive clinical course.
Slow virus diseases may be caused by conventional viruses or by the unconventional viruses
(also known as the unconventional agents or atypical viruses/agents or prions).
The symptoms associated with slow viral/prion diseases of the central nervous system tend to
have multiple neurological symptoms and different patients may present with different symptoms.
Progressive multifocal leukoencephalopathy (PML):
Rare, progressive, fatal, demyelinating disease of the CNS (kills oligodendrocytes). Non-
Get memory loss, loss of co-ordination, mentation problems, vision problems, etc.
Caused by certain members of the polyomavirus family, usually JC virus. Serology shows that
exposure to JC virus is common, but PML is rare. Patients who develop PML frequently have
some abnormality of the immune system. PML develops in up to 5% of patients with AIDS. If the
PML is associated with AIDS, HAART (highly active anti-retroviral therapy) treatment may be able
to stabilize some of these patients and their neuroradiological picture may even improve.
However, not all HIV+ve PML patients show an obvious res