Beschreibung:
Abstract Memory CD8+ T cells play a significant role in mediating protective immunity from pathogens, particularly viruses and intracellular bacteria. Inducing the optimal response, from both a quantitative and qualitative perspective, has been a research priority for determining the effectiveness of new vaccines. Depending on the pathogen, central memory (TCM) or effector memory (TEM) may be more important in providing adequate protection. Therefore, when developing new vaccines, it is important to realize which memory CD8+ T cell subset is vital and potentially ‘drive’ the response to elicit a protective level ratio in favor of one subset. Here we describe the phenotype of vaccinia specific memory CD8+ T cells. TEMRA+ memory T cells produce the most IFN-γ of any memory subset and are present in individuals last vaccinated over 30 years ago. Concurrently, we address the development of memory CD8+ T cells upon administration of Dryvax, as well as new smallpox vaccines such as Modified Vaccinia Ankara (MVA) in a murine model. Previous studies have indicated that TEM appear to provide better secondary protection than TCM and the data presented here indicate that these cells are maintained long term (>30 years). Therefore, we propose that new smallpox vaccines, such as MVA, should elicit a memory cell population in favor of TEM similar to that induced by Dryvax or other traditional smallpox vaccines.