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Comparison of neuroinvasive abilities of HSV-1 and HSV-2 in mice
1Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, México D.F., Mexico.
Abstract:
We compared neuroinvasive properties of HSV-1 MacIntyre strain and HSV-2 G strain, after inoculation of mice by intraperitoneal, intranasal and intracaudal route, by scoring for encephalitis and death. HSV-2 was more neuroinvasive than HSV-1 by any route, since mice inoculated intranasally or intracaudally with HSV-2 required 100 fold lower dose than HSV-1 to induce encephalitis and death, which occurred earlier than in HSV-1 infected mice. HSV-2 was found in brain tissues at a lower concentration (10(1.8) to 10(2.7) PFU per 0.1 g of brain) than HSV-1. Mice inoculated with HSV-2 developed a more aggressive behavior than those inoculated with HSV-1, although they showed a lower virus concentration per gram of brain. These results showed that HSV-2 G strain was more neuroinvasive than HSV-1 MacIntyre strain and its ability to produce damage of CNS was not directly related to the amount of virus in it, and suggests that neuroinvasiveness is a complex phenomenon, which could involve viral genomic expression and evasion of the immune system.
Insights
Herpes simplex virus type 2 (HSV-2) is more neuroinvasive than herpes simplex virus type 1 (HSV-1). HSV-2 causes earlier encephalitis and death in mice, independent of viral brain concentration.
Area of Science:
- Neurovirology
- Infectious Diseases
- Immunology
Background:
- Herpes simplex virus (HSV) infections can cause central nervous system (CNS) disease.
- Understanding the neuroinvasive properties of different HSV strains is crucial for predicting disease severity and developing treatments.
Purpose of the Study:
- To compare the neuroinvasive properties of HSV-1 MacIntyre strain and HSV-2 G strain in a mouse model.
- To investigate the relationship between viral load in the brain and disease severity.
Main Methods:
- Mice were inoculated via intraperitoneal, intranasal, and intracaudal routes with HSV-1 or HSV-2.
- Neuroinvasiveness was assessed by scoring for encephalitis and death.
- Viral concentration in brain tissue was quantified.
Main Results:
- HSV-2 was significantly more neuroinvasive than HSV-1 across all inoculation routes.
- Lower doses of HSV-2 were required to induce encephalitis and death compared to HSV-1.
- HSV-2 infected mice exhibited earlier onset of symptoms and mortality.
- Despite higher neuroinvasiveness, HSV-2 showed lower viral concentrations in brain tissue than HSV-1.
- Mice infected with HSV-2 displayed more aggressive behavior.
Conclusions:
- HSV-2 G strain demonstrates greater neuroinvasiveness than HSV-1 MacIntyre strain.
- The neurotropic potential of HSV-2 is not directly correlated with viral load in the CNS.
- Neuroinvasiveness is a complex multifactorial process potentially involving viral gene expression and immune evasion mechanisms.