Low-Level MHC Class II Expression Leads to Suboptimal Th Cell Response, Increased Autoaggression, and Heightened Cytokine Inducibility.

The development and activation of MHC class II (MHC-II)-restricted CD4 T cells are distinct immunological processes that are strictly MHC-II-dependent. To address their relative dependence on MHC-II, we established a novel ENU-induced mutant mouse on the C57BL/6 background, named I-A, with ∼8-fold reduced I-A expression on the surface of B cells, dendritic cells, cortical thymic epithelial cells, and medullary thymic epithelial cells. I-A and I-A mice are highly similar with respect to the numbers of double-positive thymocytes, CD4CD8 T cells, regulatory T cells, CD4 T cell marker expression, lifespan, and Th/regulatory T cell function.

Mycoviruses in Monilinia fructicola.

DsRNAs were detected in 36 of 49 Monilinia fructicola isolates from stone fruit orchards in New Zealand. The dsRNA profiles were highly variable, even between isolates from a single tree. Comparison of pathogenicity on detached fruit, in vitro growth rate, and sporulation of 14 isolates showed no obvious correlation with presence of dsRNAs.