Increased constitutive interferon-β levels and altered CD4 T cell homeostasis induced by expression of a viral glycoprotein

Constitutive IFN-I production is often regulated by resident microbiota and is essential for induction of efficient immune responses. Here, we demonstrate in transgenic (tg) mice that expression of a single viral envelope gene, the glycoprotein (GP) of lymphocytic choriomeningitis virus (LCMV), increased constitutive IFN-β levels and induced numerous IFN-stimulated genes (ISGs).

In addition, self-antigen-driven CD44highCD62Llow memory-phenotype and regulatory CD4 T cell populations were enlarged in these LCMV GP-tg mice but bona fide antigen-specific memory CD4 T cells were unchanged. In conclusion, our study shows that increased constitutive IFN-β levels induced by expression of a single viral envelope gene and accompanied by upregulated ISGs significantly altered CD4 T cell homeostasis. Furthermore, our data imply that a pathway capable of upregulating constitutive IFN-β levels can sense LCMV GP expression in vivo.