Maximus Peto’s Commentary
These researchers report on the effectiveness of a vaccine for mouse CMV that looks to be effective. Deciding whether this epitope can be used in human CMV, and whether it would be effective in humans, including for people already infected with CMV, presumably needs further research.
Immune Protection by a Cytomegalovirus Vaccine Vector Expressing a Single Low-Avidity Epitope.
J Immunol. 2017 Sep 1;199(5):1737-1747.
Borkner L, Sitnik KM, Dekhtiarenko I, Pulm AK, Tao R, Drexler I, Cicin-Sain L
PubMed publication date (edat): 8/5/2017
Experimental CMV-based vaccine vectors expressing a single MHC class I-restricted high-avidity epitope provided strong, T cell-dependent protection against viruses or tumors. In this study we tested the low-avidity epitope KCSRNRQYL, and show that a mouse CMV (MCMV) vector provides complete immune control of recombinant vaccinia virus expressing the same epitope if KCSRNRQYL is expressed within the immediate-early MCMV gene ie2 The same epitope expressed within the early M45 gene provided no protection, although MCMV vectors expressing the high-avidity epitope SSIEFARL induced protective immunity irrespective of gene expression context. Immune protection was matched by Ag-induced, long-term expansion of effector memory CD8 T cells, regardless of epitope avidity. We explained this pattern by observing regularities in Ag competition, where responses to high-avidity epitopes outcompeted weaker ones expressed later in the replicative cycle of the virus. Conversely, robust and early expression of a low-avidity epitope compensated its weak intrinsic antigenicity, resulting in strong and sustained immunity and immune protection.