Human foamy virus infection activates class I major histocompatibility complex antigen expression

Abstract

We examined the effect of human foamy virus (HFV) infection on the expression of human major histocompatibility complex molecules. Our data show that in vitro HFV infection of U373-MG glioblastoma cells results in increased expression of class I human leukocyte antigen (HLA) and transcripts. Transient transfection assays of plasmids containing the reporter gene chloramphenicol acetyl transferase driven by different 5' deletions of the HLA-All class ! promoter allowed identification of eis-acting elements involved in this regulation. HFV infection has two opposite effects on the HLA class I promoter: transactivation of the HLAAll promoter through a positive regulatory element located in the -525 to -335 region upstream of exon 1 and down-regulation of transcriptional activity driven by the -335 to -205 class I promoter region. Additional experimental data indicate that the effect of HFV on HLA class I expression is not mediated by the interferon pathway.

Innate Sensing of Foamy Viruses by Human Hematopoietic Cells

“…In particular, the interaction of FV with the human immune system remains poorly characterized. It has been suggested that FV does not activate an innate response (10,62). Previous experiments were performed mostly with human or simian epithelial cell lines, and the response of human hematopoietic cells to the virus is not known.…”

“…Very little is known about the sensing of FV. A few reports, published almost 2 decades ago, described an absence of type I IFN production by human and primate cell lines (such as U373-MG glioblastoma cells and AV3 embryonic amniotic cells) upon FV infection (10,60,62). However, how pDCs and other hematopoietic cells react when they encounter FV has not been investigated thus far.…”

Early Events in Foamy Virus—Host Interaction and Intracellular Trafficking

“…Innate immune system sensing of FV infections is poorly characterized. A failure of FVs to induce type I interferon (IFN-I) was suggested by early studies using primate or human cell lines [73,74,75]. A very recent study by Rua and colleagues, however, demonstrates that FVs are efficiently sensed by primary human hematopoietic cells [76].…”

A new sensitive indicator cell line reveals cross-transactivation of the viral LTR by gorilla and chimpanzee simian foamy viruses

“…Our results underline the importance of extending current knowledge beyond the most studied prototype strain. Indeed, Tas interacts with promoters from host genes (Colas et al, 1995;Kido et al, 2002;Wagner et al, 2000;Wang et al, 2010), may be involved in clinically relevant interactions with lentiviruses (Choudhary et al, 2013), and is a potential (but still controversial) target of the immune system (Meiering and Linial, 2003;Regad et al, 2001).…”