Inhibition of STAT 1 Phosphorylation by Human Parainfluenza Virus Type 3 C Protein

The P mRNA of the viruses belonging to the subfamily Paramyxovirinae possesses a unique property of giving rise to several accessory proteins by a process that involves the utilization of overlapping open reading frames (the C proteins) and by an “RNA-editing” mechanism (the V proteins). Although these proteins are considered accessory, numerous studies have highlighted the importance of these proteins in virus transcription and interferon signaling, including our previous observation on the role of human parainfluenza virus type 3 (HPIV 3) C protein in the transcription of viral genome (Malur et al., Virus Res. 99:199-204, 2004). In this report, we have addressed its role in interferon signaling by generating a stable cell line, L-C6, by using the lentiviral expression system which expresses HPIV 3 C protein. The L-C6 cells were efficient in abrogating both alpha and gamma interferon-induced antiviral states and demonstrated a drastic reduction in the formation of gamma-activated factor complexes in the cell extracts. Western blot analysis subsequently revealed a defect in the phosphorylation of STAT 1 in these cells. Taken together, our results indicate that HPIV 3 C protein is capable of counteracting the interferon signaling pathway by specifically inhibiting the activation of STAT 1

Regulated release of L13a from the 60S ribosomal subunit as a mechanism of transcript-specific translational control

Transcript-specific translational control is generally directed by binding of trans-acting proteins to struc-tural elements in the untranslated region (UTR) of the target mRNA. Here, we elucidate a translational silenc-ing mechanism involving regulated release of an inte-gral ribosomal protein and subsequent binding to its target mRNA. Human ribosomal protein L13a was identified as a candidate interferon-Gamma-Activated Inhibitor of Translation (GAIT) of ceruloplasmin (Cp) mRNA by a genetic screen for Cp 3�-UTR binding proteins. In vitro activity of L13a was shown by inhibition of target mRNA translation by recombinant protein. In response to interferon- � in vivo, the entire cellular pool of L13a was phosphorylated and released from the 60S ribosomal subunit. Released L13a specifically bound the 3�-UTR GAIT element of Cp mRNA and si-lenced translation. We propose a model in which the ribosome functions not only as a protein synthesis machine, but also as a depot for regulatory proteins that modulate translation

The Toll-Like Receptor 5 Agonist Entolimod Mitigates Lethal Acute Radiation Syndrome in Non-Human Primates.

There are currently no approved medical radiation countermeasures (MRC) to reduce the lethality of high-dose total body ionizing irradiation expected in nuclear emergencies. An ideal MRC would be effective even when administered well after radiation exposure and would counteract the effects of irradiation on the hematopoietic system and gastrointestinal tract that contribute to its lethality. Entolimod is a Toll-like receptor 5 agonist with demonstrated radioprotective/mitigative activity in rodents and radioprotective activity in non-human primates. Here, we report data from several exploratory studies conducted in lethally irradiated non-human primates (rhesus macaques) treated with a single intramuscular injection of entolimod (in the absence of intensive individualized supportive care) administered in a mitigative regimen, 1-48 hours after irradiation. Following exposure to LD50-70/40 of radiation, injection of efficacious doses of entolimod administered as late as 25 hours thereafter reduced the risk of mortality 2-3-fold, providing a statistically significant (P<0.01) absolute survival advantage of 40-60% compared to vehicle treatment. Similar magnitude of survival improvement was also achieved with drug delivered 48 hours after irradiation. Improved survival was accompanied by predominantly significant (P<0.05) effects of entolimod administration on accelerated morphological recovery of hematopoietic and immune system organs, decreased severity and duration of thrombocytopenia, anemia and neutropenia, and increased clonogenic potential of the bone marrow compared to control irradiated animals. Entolimod treatment also led to reduced apoptosis and accelerated crypt regeneration in the gastrointestinal tract. Together, these data indicate that entolimod is a highly promising potential life-saving treatment for victims of radiation disasters

Enhanced morphological recovery of hematopoietic and lymphoid organs in NHPs treated with entolimod post-irradiation.

<p>NHPs were treated with a single injection of 40 μg/kg entolimod 16, 25 or 48 hours after LD_75/40 total body irradiation (TBI). Tissue morphology was assessed 40 days post-irradiation and compared to that in control NHPs treated with vehicle 16 hours after LD_75/40 TBI. Representative histological images (hematoxylin-eosin staining) of sternum bone marrow sections, thymuses, spleens and mesenteric lymph nodes of animals that survived to study termination on Day 40 post-TBI (study Rs-06) are shown. Scale bars: 100 μm for bone marrow, 200 μm for thymus, spleen, and lymph node.</p

Histological evaluation of hematopoietic/lymphoid organs from NHPs that survived to day 40 after 6.5 Gy TBI and vehicle or entolimod treatment (study Rs-06)

<p>^A Scoring was performed based on a 5-grade scale developed for each organ: 0 –total aplasia; 1 –pronounced atrophy, 2 –moderate atrophy, 3 –slight atrophy, close to normal morphology; 4 –normal morphology. Scoring criteria for individual organs are described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135388#pone.0135388.s008" target="_blank">S1 Methods</a>.</p><p>^B Student’s t-test vs. vehicle, 2-tailed.</p><p>Histological evaluation of hematopoietic/lymphoid organs from NHPs that survived to day 40 after 6.5 Gy TBI and vehicle or entolimod treatment (study Rs-06)</p