Virus-like interference in the latency and prevention of Creutzfeldt-Jakob disease

Area of Science:

• Neuroscience
• Immunology
• Infectious Diseases

Background:

• Previous studies demonstrated that intracerebral inoculation with an attenuated Creutzfeldt-Jakob disease (CJD) strain (SY) delays clinical signs and neuropathology from a subsequent virulent strain (FU).
• The underlying mechanisms of this protective effect require further investigation.

Purpose of the Study:

• To investigate the protective effects of attenuated CJD strain SY against virulent strain FU challenge in mice.
• To explore the role of innate immunity and potential inhibitory factors in this protective response.

Main Methods:

• Mice were intracerebrally inoculated with attenuated SY strain and/or virulent FU strain at lower doses.
• Brain and serum samples were collected to assess inhibitory factors.
• FU infectivity was tested after mixing with SY brain homogenates or serum.
• Protection was evaluated based on survival, neuropathology, and presence of PrP-res.

Main Results:

• Mice inoculated with lower doses of SY and FU were protected into old age without neuropathology or PrP-res, unlike FU-only controls which succumbed a year earlier.
• SY brain homogenates, but not serum, significantly reduced FU infectivity, suggesting labile inhibitory factors from brain cells.
• Intravenous inoculation of SY provided strong protection against high-dose FU challenge.
• Innate immunity, particularly myeloid microglia, is implicated in the observed protection.

Conclusions:

• Attenuated CJD strain SY confers long-term protection against virulent FU strain, likely mediated by innate immune responses.
• Labile inhibitory factors produced by brain cells contribute to this protective effect.
• Targeting myeloid pathways presents a potential strategy for preventing or delaying CJD progression.