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Viruses, chemotherapy and immunity
1Infectious Disease Unit, Massachusetts General Hospital, Boston.
Abstract:
An increasing number of antiviral agents are presently in various stages of development and testing, and an increasing number have recently been licensed for use in humans. These drugs have been used extensively to treat viral infections in immunocompromised individuals, and these studies indicate that for many antiviral agents the response to therapy is highly dependent on the integrity of the underlying host immune response. In particular, the response to zidovudine, acyclovir and ganciclovir in persons with HIV-1 infection is highly dependent upon CD4 number, which can be considered a surrogate marker for the state of host immune function in these subjects. Responses to interferons likewise can be shown to depend on the host immune response, with responses due to both direct antiviral effects of this agent as well as immunomodulatory effects mediated through interferon-induced upregulation of HLA molecule expression. The interdependence of host immunity with antiviral efficacy is underscored by the increased antiviral drug resistance in persons with advanced degrees of chronic immunosuppression, related to the higher level of viral replication and viraemia which occurs in the absence of an effective host immune response. Further definition of the precise mechanisms of these interactions should facilitate the rational design of antiviral agents and immunomodulatory therapies to improve treatment of viral infections.
Insights
The effectiveness of antiviral drugs relies heavily on the patient's immune system. Optimizing antiviral and immunomodulatory therapies requires understanding these complex interactions for better viral infection treatment.
Area of Science:
- Virology
- Immunology
- Pharmacology
Background:
- Numerous antiviral agents are in development and clinical use.
- Antiviral drug efficacy is significantly influenced by the host immune response, particularly in immunocompromised individuals.
- Specific antiviral drugs like zidovudine, acyclovir, and ganciclovir show variable responses in HIV-1 patients based on CD4+ T-cell counts.
Purpose of the Study:
- To explore the interdependence between host immunity and antiviral agent efficacy.
- To highlight the role of immune status in determining treatment outcomes for viral infections.
- To underscore the mechanisms underlying antiviral drug resistance in immunosuppressed individuals.
Main Methods:
- Review of existing studies on antiviral therapy in various patient populations.
- Analysis of the impact of immune markers (e.g., CD4 count) on antiviral drug response.
- Examination of interferon's dual role (direct antiviral and immunomodulatory effects).
Main Results:
- Antiviral therapy response is strongly correlated with the integrity of the host immune system.
- CD4+ T-cell counts serve as a crucial indicator for predicting zidovudine, acyclovir, and ganciclovir efficacy in HIV-1 patients.
- Interferon response involves both direct antiviral actions and immune modulation via HLA molecule expression.
- Increased viral replication and drug resistance are observed in individuals with advanced immunosuppression due to weakened immune responses.
Conclusions:
- The host immune response is a critical determinant of antiviral treatment success.
- Understanding the interplay between immunity and antiviral drugs is essential for developing effective therapies.
- Further research into these mechanisms will aid in designing improved antiviral and immunomodulatory treatments for viral infections.