Immunization against smallpox was always considered successful if a skin lesion formed at the site of vaccination. As researchers are looking to use vaccinia virus, the virus in the smallpox vaccine, in other therapeutics and preventative vaccines, it is important to characterize more extensively the mechanisms by which the immune system controls vaccinia virus and thereby protects against smallpox.
In this regard, Behazine Combadière and colleagues, at INSERM U945, France, have now determined that immune cells known as CD4+ T cells have an important role in controlling skin lesion size at sites of revaccination.
In the study, the number of effector CD4+ T cells targeting vaccinia virus that a person who was immunized against smallpox many years previously had in their blood prior to revaccination was the only immune correlate that determined the size of their skin lesion upon revaccination. Specifically, high numbers of these cells correlated with small skin lesion size upon revaccination.
These data provide new insight into the mechanisms of immune control of vaccinia virus, highlighting a role for an immune cell not previously thought to be centrally involved in the process.
The research appears in the Journal of Clinical Investigation.
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