Detection of herpes simplex virus type 1 latency-associated transcript expression in trigeminal ganglia by in situ...

Area of Science:

• Virology
• Neuroscience
• Infectious Diseases

Background:

• Herpes simplex virus type 1 (HSV-1) establishes lifelong latency in neurons.
• Previous studies using in situ PCR showed more neurons harbor HSV-1 genomes than express latency-associated transcripts (LATs).

Purpose of the Study:

• To determine if all neurons containing HSV-1 genomes express LATs.
• To investigate LAT expression levels at different time points post-infection.

Main Methods:

• Corneal scarification of trigeminal ganglia in mice with a ribonucleotide reductase-deficient HSV-1 strain.
• In situ reverse transcriptase PCR was used to detect LAT expression.
• Comparison with in situ hybridization for LATs and in situ PCR for viral genomes.

Main Results:

• A significantly greater number of LAT-positive cells were detected by in situ reverse transcriptase PCR compared to in situ hybridization.
• The number of LAT-expressing neurons closely matched the number of neurons containing HSV-1 genomes.
• LAT expression was observed in many neurons harboring HSV-1 genomes, 1 and 8 weeks post-infection.

Conclusions:

• HSV-1 LAT expression is more widespread in latently infected neurons than previously thought.
• This finding suggests a broader role for LATs in the HSV-1 lifecycle during latency.
• More neurons harbor HSV-1 genomes and express LATs than detected by traditional methods.