Related Experiment Video
Updated: Jul 10, 2026
Vaccinia Virus Infection & Temporal Analysis of Virus Gene Expression: Part 1
Published on: April 8, 2009
Immunogenicity of a highly attenuated MVA smallpox vaccine and protection against monkeypox
Patricia L Earl1, Jeffrey L Americo, Linda S Wyatt
1National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0445, USA.
Abstract:
The potential use of smallpox as a biological weapon has led to the production and stockpiling of smallpox vaccine and the immunization of some healthcare workers. Another public health goal is the licensing of a safer vaccine that could benefit the millions of people advised not to take the current one because they or their contacts have increased susceptibility to severe vaccine side effects. As vaccines can no longer be tested for their ability to prevent smallpox, licensing will necessarily include comparative immunogenicity and protection studies in non-human primates. Here we compare the highly attenuated modified vaccinia virus Ankara (MVA) with the licensed Dryvax vaccine in a monkey model. After two doses of MVA or one dose of MVA followed by Dryvax, antibody binding and neutralizing titres and T-cell responses were equivalent or higher than those induced by Dryvax alone. After challenge with monkeypox virus, unimmunized animals developed more than 500 pustular skin lesions and became gravely ill or died, whereas vaccinated animals were healthy and asymptomatic, except for a small number of transient skin lesions in animals immunized only with MVA.
Insights
A new modified vaccinia virus Ankara (MVA) vaccine shows promising results for smallpox prevention. This safer vaccine candidate demonstrated strong immune responses and protection against monkeypox virus in a primate model.
Area of Science:
- Virology
- Immunology
- Vaccinology
Background:
- Smallpox biodefense necessitates vaccine production and stockpiling.
- A safer smallpox vaccine is needed for individuals advised against current vaccines due to side effect risks.
Purpose of the Study:
- To compare the immunogenicity and protective efficacy of modified vaccinia virus Ankara (MVA) against the licensed Dryvax vaccine.
- To evaluate MVA as a potential safer alternative for smallpox immunization.
Main Methods:
- Comparative study of MVA and Dryvax in a non-human primate model.
- Assessment of antibody binding, neutralizing titers, and T-cell responses.
- Challenge study using monkeypox virus to evaluate vaccine protection.
Main Results:
- MVA vaccination induced equivalent or higher antibody and T-cell responses compared to Dryvax.
- All vaccinated animals were protected against severe illness and death from monkeypox virus challenge.
- Animals receiving MVA showed minimal, transient skin lesions, unlike unvaccinated controls.
Conclusions:
- Modified vaccinia virus Ankara (MVA) is a viable candidate for a safer smallpox vaccine.
- MVA demonstrates robust immunogenicity and protective efficacy in a non-human primate model.
- Further studies support MVA's potential for public health use in smallpox preparedness.
Related Concept Videos
00:42Cross-reactivity
01:51Vaccinations
01:23Immunological Memory
What is Immunological Memory?
Immunological memory is an integral function of the immune system that allows it to recognize and react more rapidly and effectively to pathogens previously encountered. This feature is...
01:21Vaccines
01:24Smallpox
01:17Poliomyelitis