Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe disease in human with an overall case-fatality rate of >35%. Effective antivirals are crucial for improving the clinical outcome of MERS. Although a number of repurposed drugs, convalescent-phase plasma, antiviral peptides, and neutralizing antibodies exhibit anti-MERS-CoV activity in vitro, most are not readily available or have not been evaluated in nonhuman primates. We assessed 3 repurposed drugs with potent in vitro anti-MERS-CoV activity (mycophenolate mofetil [MMF], lopinavir/ritonavir, and interferon-β1b) in common marmosets with severe disease resembling MERS in humans. The lopinavir/ritonavir-treated and interferon-β1b-treated animals had better outcome than the untreated animals, with improved clinical (mean clinical scores ↓50.9%–95.0% and ↓weight loss than the untreated animals), radiological (minimal pulmonary infiltrates), and pathological (mild bronchointerstitial pneumonia) findings, and lower mean viral loads in necropsied lung (↓0.59–1.06 log₁₀ copies/glyceraldehyde 3-phosphate dehydrogenase [GAPDH]; P < .050) and extrapulmonary (↓0.11–1.29 log₁₀ copies/GAPDH; P < .050 in kidney) tissues. In contrast, all MMF-treated animals developed severe and/or fatal disease with higher mean viral loads (↑0.15–0.54 log₁₀ copies/GAPDH) than the untreated animals. The mortality rate at 36 hours postinoculation was 67% (untreated and MMF-treated) versus 0–33% (lopinavir/ritonavir-treated and interferon-β1b-treated). Lopinavir/ritonavir and interferon-β1b alone or in combination should be evaluated in clinical trials. MMF alone may worsen MERS and should not be used.

Pancreatic cancer is a disease with an extremely poor prognosis. Tumor protein 53-induced nuclear protein 1 ( TP53INP1 ) is a proapoptotic stress-induced p53 target gene. In this article, we show by immunohistochemical analysis that TP53INP1 expression is dramatically reduced in pancreatic ductal adenocarcinoma (PDAC) and this decrease occurs early during pancreatic cancer development. TP53INP1 reexpression in the pancreatic cancer-derived cell line MiaPaCa2 strongly reduced its capacity to form s.c., i.p., and intrapancreatic tumors in nude mice. This anti-tumoral capacity is, at least in part, due to the induction of caspase 3-mediated apoptosis. In addition, TP53INP1 ^−/− mouse embryonic fibroblasts (MEFs) transformed with a retrovirus expressing E1A/ras ^V12 oncoproteins developed bigger tumors than TP53INP1 ^+/+ transformed MEFs or TP53INP1 ^−/− transformed MEFs with restored TP53INP1 expression. Finally, TP53INP1 expression is repressed by the oncogenic micro RNA miR-155, which is overexpressed in PDAC cells. TP53INP1 is a previously unknown miR-155 target presenting anti-tumoral activity.

Middle East respiratory syndrome (MERS) is associated with a mortality rate of >35%. We previously showed that MERS coronavirus (MERS-CoV) could infect human macrophages and dendritic cells and induce cytokine dysregulation. Here, we further investigated the interplay between human primary T cells and MERS-CoV in disease pathogenesis. Importantly, our results suggested that MERS-CoV efficiently infected T cells from the peripheral blood and from human lymphoid organs, including the spleen and the tonsil. We further demonstrated that MERS-CoV infection induced apoptosis in T cells, which involved the activation of both the extrinsic and intrinsic apoptosis pathways. Remarkably, immunostaining of spleen sections from MERS-CoV–infected common marmosets demonstrated the presence of viral nucleoprotein in their CD3⁺ T cells. Overall, our results suggested that the unusual capacity of MERS-CoV to infect T cells and induce apoptosis might partly contribute to the high pathogenicity of the virus.

Short interfering RNAs (siRNAs) have been used to inhibit HIV-1 replication. The durable inhibition of HIV-1 replication by RNA interference has been impeded, however, by a high mutation rate when viral sequences are targeted and by cytotoxicity when cellular genes are knocked down. To identify cellular proteins that contribute to HIV-1 replication that can be chronically silenced without significant cytotoxicity, we employed a shRNA library that targets 54,509 human transcripts. We used this library to select a comprehensive population of Jurkat T-cell clones, each expressing a single discrete shRNA. The Jurkat clones were then infected with HIV-1. Clones that survived viral infection represent moieties silenced for a human mRNA needed for virus replication, but whose chronic knockdown did not cause cytotoxicity. Overall, 252 individual Jurkat mRNAs were identified. Twenty-two of these mRNAs were secondarily verified for their contributions to HIV-1 replication. Five mRNAs, NRF1, STXBP2, NCOA3, PRDM2, and EXOSC5, were studied for their effect on steps of the HIV-1 life cycle. We discuss the similarities and differences between our shRNA findings for HIV-1 using a spreading infection assay in human Jurkat T-cells and results from other investigators who used siRNA-based screenings in HeLa or 293T cells.

Small non-coding RNAs of 18–25 nt in length can regulate gene expression through the RNA interference (RNAi) pathway. To characterize small RNAs in HIV-1-infected cells, we performed linker-ligated cloning followed by high-throughput pyrosequencing. Here, we report the composition of small RNAs in HIV-1 productively infected MT4 T-cells. We identified several HIV-1 small RNA clones and a highly abundant small 18-nt RNA that is antisense to the HIV-1 primer-binding site (PBS). This 18-nt RNA apparently originated from the dsRNA hybrid formed by the HIV-1 PBS and the 3′ end of the human cellular tRNAlys3. It was found to associate with the Ago2 protein, suggesting its possible function in the cellular RNAi machinery for targeting HIV-1.