Related Experiment Videos
Spontaneous molecular reactivation of herpes simplex virus type 1 latency in mice
Lawrence T Feldman1, Aaron R Ellison, Cynthia C Voytek
1Department of Microbiology and Immunology, University of California Medical Center, Los Angeles, CA 90024, USA.
Abstract:
Infection of the mouse trigeminal ganglia (TG) is the most commonly used model for the study of herpes simplex virus type 1 (HSV-1) latency. Its popularity is caused, at least in part, by the perception that latent infection can be studied in this system in the absence of spontaneous viral reactivation. However, this perception has never been rigorously tested. To carefully study this issue, the eyes of Swiss-Webster mice were inoculated with HSV-1 (KOS), and 37-47 days later the TG were dissected, serial-sectioned, and probed for HSV-1 ICP4, thymidine kinase, glycoprotein C, and latency-associated transcript RNA by in situ hybridization. Serial sections of additional latently infected TG were probed with HSV-1-specific polyclonal antisera. Analysis of thousands of probed sections revealed abundant expression of viral transcripts, viral protein, and viral DNA replication in about 1 neuron per 10 TG tested. These same neurons were surrounded by a focal white cell infiltrate, indicating the presence of an antigenic stimulus. We conclude that productive cycle viral genes are abundantly expressed in rare neurons of latently infected murine TG and that these events are promptly recognized by an active local immune response. In the absence of detectable infectious virus in these ganglia, we propose the term "spontaneous molecular reactivation" to describe this ongoing process.
Insights
Herpes simplex virus type 1 (HSV-1) latency in mouse trigeminal ganglia (TG) involves spontaneous molecular reactivation. Rare neurons show viral gene expression and immune response, challenging the absence of reactivation theory.
Area of Science:
- Neurovirology
- Immunology
Background:
- The mouse trigeminal ganglia (TG) model is widely used for studying herpes simplex virus type 1 (HSV-1) latency.
- This model is perceived to allow study of latent HSV-1 infection without spontaneous viral reactivation.
Purpose of the Study:
- To rigorously test the perception that spontaneous viral reactivation does not occur in the murine TG model of HSV-1 latency.
- To investigate the presence and nature of viral activity during latency in TG.
Main Methods:
- Swiss-Webster mice were inoculated with HSV-1 (KOS) in the eyes.
- TG were dissected 37-47 days post-inoculation and analyzed using in situ hybridization for viral transcripts (ICP4, thymidine kinase, glycoprotein C, latency-associated transcript RNA).
- Serial sections were probed for viral proteins using HSV-1-specific antisera.
Main Results:
- Abundant expression of viral transcripts, viral protein, and viral DNA replication was detected in approximately 1 in 10 TG tested.
- These rare neurons exhibiting viral activity were surrounded by a focal white cell infiltrate, indicating an immune response.
- No infectious virus was detectable in the ganglia.
Conclusions:
- Productive cycle viral genes are abundantly expressed in rare neurons of latently infected murine TG.
- These events trigger a prompt and active local immune response.
- The term "spontaneous molecular reactivation" is proposed to describe this ongoing process in the absence of detectable infectious virus.