Herpes simplex encephalitis in the temporal cortex and limbic system after trigeminal nerve inoculation

Area of Science:

• Neurovirology
• Infectious Diseases

Background:

• Herpes simplex virus type 1 (HSV-1) causes human encephalitis, typically affecting the temporal lobe and limbic system.
• The pattern of lesions suggests transneuronal spread from a single entry point, with olfactory and trigeminal nerves as likely candidates.
• Previous experimental trigeminal nerve infections did not replicate the human disease pattern.

Purpose of the Study:

• To investigate the role of the trigeminal nerve, specifically its mandibular division, in the pathogenesis of HSV-1 encephalitis.
• To determine if selective trigeminal nerve infection can reproduce the characteristic lesion distribution observed in human cases.

Main Methods:

• Direct inoculation of HSV-1 into the murine tooth pulp to selectively infect the mandibular division of the trigeminal nerve.
• Observation and analysis of the resulting encephalitis pattern in the infected mice.

Main Results:

• Selective infection of the mandibular trigeminal nerve via tooth pulp inoculation.
• Development of encephalitis primarily affecting the temporal cortex and limbic system in the inoculated mice.
• This pattern mirrors the distribution of lesions seen in human HSV-1 encephalitis.

Conclusions:

• Spread of HSV-1 via the trigeminal nerve, particularly its mandibular division, provides a plausible explanation for the characteristic temporal lobe and limbic system involvement in human encephalitis.
• This finding clarifies the neuroanatomical pathway of HSV-1 entry and spread in the central nervous system.