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Herpes simplex virus type 2 vaccines: new ground for optimism?
1Virology and Immunology Laboratories, Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. laurelia@umaryland.edu
Clinical and Diagnostic Laboratory Immunology
|May 13, 2004
Summary
Developing genital herpes vaccines is challenging due to the virus's complex life cycle. Effective vaccines require inducing T helper 1 (Th1) immunity while limiting Th2 cytokines like interleukin-10 (IL-10).
Area of Science:
- Virology
- Immunology
- Vaccinology
Background:
- Genital herpes vaccine development faces challenges due to the herpes simplex virus (HSV) life cycle, including latency.
- Understanding immune control mechanisms for primary and recurrent HSV disease is crucial for vaccine design.
- T helper 1 (Th1) cytokines and innate immunity prevent recurrent disease, while Th2 cytokines and regulatory T cells promote it.
Purpose of the Study:
- To explore the immunological basis for effective prophylactic and therapeutic vaccines against genital herpes.
- To identify key immune responses, specifically T helper 1 (Th1) and T helper 2 (Th2) cytokines, influencing HSV disease control.
- To evaluate the potential of novel vaccine strategies targeting immune modulation for therapeutic benefit.
Main Methods:
- Review of studies on immune responses to HSV, focusing on effector cells and cytokine profiles (Th1 vs. Th2).
- Analysis of clinical trial data for vaccines targeting HSV-2 glycoprotein D (gD-2) with Th1-inducing adjuvants.
- Evaluation of a growth-defective HSV-2 mutant (ICP10DeltaPK) vaccine lacking the Th2-polarizing gene ICP10PK.
Main Results:
- Recurrent genital herpes is prevented by virus-specific Th1 cytokines (e.g., gamma interferon) and activated innate immunity.
- Th2 cytokines, such as interleukin-10 (IL-10), and regulatory T cells suppress protective immunity, allowing viral replication.
- A gD-2 vaccine with a Th1 adjuvant showed prophylactic activity in seronegative females.
- The ICP10DeltaPK vaccine demonstrated therapeutic activity, preventing recurrences in 44% and reducing frequency/severity in others.
Conclusions:
- Effective therapeutic vaccines for genital herpes must induce Th1 immunity and limit Th2 cytokine production, particularly IL-10.
- Recent clinical trials support the strategy of modulating immune responses to combat HSV-2.
- Further evaluation of Th1-inducing and growth-defective viral vaccines is warranted for genital herpes treatment.