In Vivo Interaction of the Hepatitis Delta Virus Small Antigen with the ELAV-Like Protein HuR

Abstract

The small and large delta antigens (S-HDAg and L-HDAg, respectively) represent two forms of the only protein encoded by the hepatitis delta virus (HDV) RNA genome. Consequently, HDV relies, at a large extent, on the host cell machinery for replication and transcription. Until now, only a limited number of cellular proteins were identified as S-HDAg or L-HDAg partners being involved in the modulation of the virus life cycle. In an attempt to identify cellular S-HDAg-binding proteins we made use of a yeast two-hybrid approach to screen a human liver cDNA library. We were able to identify HuR, a ubiquitously expressed protein involved in RNA stabilization, as an S-HDAg partner both in vitro and in vivo. HuR was found to be overexpressed and colocalize with HDAg in human hepatoma cells. siRNA knockdown of HuR mRNA resulted in inhibition of S-HDAg and L-HDAg expression.

A Rapid Point-of-Care Test for the Serodiagnosis of Hepatitis Delta Virus Infection

“…Interestingly, antigen-antibody binding on the rapid test was possible despite using denatured rL-HDAg. This is in agreement with previous studies which found that large segments of the HDAg protein sequence are intrinsically disordered but maintain the ability to form protein-protein interactions [33][34][35][36].…”

Identification of a Novel Human LAP1 Isoform That Is Regulated by Protein Phosphorylation

“…Myc-LAP1B and pET-LAP1B constructs have been previously described [15] . The pSIREN-RetroQ vector (Clontech) was kindly provided by Dr. Celso Cunha from the Instituto de Higiene e Medicina Tropical , Lisbon [17] . LAP1C was prepared by PCR amplification using the following primers: 5′-GAATTCATATGAAGACGCGAAGGAC-3′ and 5′-CTCGAGTTATAAGCAGATGCCCCT-3.…”