Seneca Valley virus (SVV) is an oncolytic picornavirus with selective tropism for neuroendocrine cancers. It has shown promise as a cancer therapeutic in preclinical studies and early-phase clinical trials. Here, we have identified anthrax toxin receptor 1 (ANTXR1) as the receptor for SVV using genome-wide loss-of-function screens. ANTXR1 is necessary for permissivity in vitro and in vivo. However, robust SVV replication requires an additional innate immune defect. We found that SVV interacts directly and specifically with ANTXR1, that this interaction is required for SVV binding to permissive cells, and that ANTXR1 expression is necessary and sufficient for infection in cell lines with decreased expression of antiviral IFN genes at baseline. Finally, we identified the region of the SVV capsid that is responsible for receptor recognition using cryoelectron microscopy of the SVV-ANTXR1-Fc complex. These studies identify ANTXR1, a class of receptor that is shared by a mammalian virus and a bacterial toxin, as the cellular receptor for SVV.
Linde A. Miles, Laura N. Burga, Eric E. Gardner, Mihnea Bostina, John T. Poirier, Charles M. Rudin
Chronic viral infections are difficult to treat, and new approaches are needed, particularly those aimed at reducing reactivation by enhancing immune responses. Herpes simplex virus (HSV) establishes latency and reactivates frequently, and breakthrough reactivation can occur despite suppressive antiviral therapy. Virus-specific T cells are important to control HSV, and proliferation of activated T cells requires increased metabolism of glutamine. Here, we found that supplementation with oral glutamine reduced virus reactivation in latently HSV-1–infected mice and HSV-2–infected guinea pigs. Transcriptome analysis of trigeminal ganglia from latently HSV-1–infected, glutamine-treated WT mice showed upregulation of several IFN-γ–inducible genes. In contrast to WT mice, supplemental glutamine was ineffective in reducing the rate of HSV-1 reactivation in latently HSV-1–infected IFN-γ–KO mice. Mice treated with glutamine also had higher numbers of HSV-specific IFN-γ–producing CD8 T cells in latently infected ganglia. Thus, glutamine may enhance the IFN-γ–associated immune response and reduce the rate of reactivation of latent virus infection.
Kening Wang, Yo Hoshino, Kennichi Dowdell, Marta Bosch-Marce, Timothy G. Myers, Mayra Sarmiento, Lesley Pesnicak, Philip R. Krause, Jeffrey I. Cohen
The antiviral restriction factor IFN-induced transmembrane protein 3 (IFITM3) inhibits cell entry of a number of viruses, and genetic diversity within
Maria A. Stacey, Simon Clare, Mathew Clement, Morgan Marsden, Juneid Abdul-Karim, Leanne Kane, Katherine Harcourt, Cordelia Brandt, Ceri A. Fielding, Sarah E. Smith, Rachael S. Wash, Silvia Gimeno Brias, Gabrielle Stack, George Notley, Emma L. Cambridge, Christopher Isherwood, Anneliese O. Speak, Zoë Johnson, Walter Ferlin, Simon A. Jones, Paul Kellam, Ian R. Humphreys
Global health is threatened by emerging viral infections, which largely lack effective vaccines or therapies. Targeting host pathways that are exploited by multiple viruses could offer broad-spectrum solutions. We previously reported that AAK1 and GAK, kinase regulators of the host adaptor proteins AP1 and AP2, are essential for hepatitis C virus (HCV) infection, but the underlying mechanism and relevance to other viruses or in vivo infections remained unknown. Here, we have discovered that AP1 and AP2 cotraffic with HCV particles in live cells. Moreover, we found that multiple viruses, including dengue and Ebola, exploit AAK1 and GAK during entry and infectious virus production. In cultured cells, treatment with sunitinib and erlotinib, approved anticancer drugs that inhibit AAK1 or GAK activity, or with more selective compounds inhibited intracellular trafficking of HCV and multiple unrelated RNA viruses with a high barrier to resistance. In murine models of dengue and Ebola infection, sunitinib/erlotinib combination protected against morbidity and mortality. We validated sunitinib- and erlotinib-mediated inhibition of AAK1 and GAK activity as an important mechanism of antiviral action. Additionally, we revealed potential roles for additional kinase targets. These findings advance our understanding of virus-host interactions and establish a proof of principle for a repurposed, host-targeted approach to combat emerging viruses.
Elena Bekerman, Gregory Neveu, Ana Shulla, Jennifer Brannan, Szu-Yuan Pu, Stanley Wang, Fei Xiao, Rina Barouch-Bentov, Russell R. Bakken, Roberto Mateo, Jennifer Govero, Claude M. Nagamine, Michael S. Diamond, Steven De Jonghe, Piet Herdewijn, John M. Dye, Glenn Randall, Shirit Einav
Persistent hepatitis B virus (HBV) infection is established by the formation of an intranuclear pool of covalently closed circular DNA (cccDNA) in the liver. Very little is known about the intrahepatic distribution of HBV cccDNA in infected patients, particularly at the single-cell level. Here, we established a highly sensitive and specific ISH assay for the detection of HBV RNA, DNA, and cccDNA. The specificity of our cccDNA probe set was confirmed by its strict intranuclear signal and by a series of Southern blot analyses. Use of our in situ assay in conjunction with IHC or immunofluorescence uncovered a surprisingly mosaic distribution of viral antigens and nucleic acids. Most strikingly, a mutually exclusive pattern was found between HBV surface antigen–positive (HBsA-positive) and HBV DNA– and cccDNA-positive cells. A longitudinal observation of patients over a 1-year period of adeforvir therapy confirmed the persistence of a nuclear reservoir of viral DNA, although cytoplasmic DNA was effectively depleted in these individuals. In conclusion, our method for detecting viral nucleic acids, including cccDNA, with single-cell resolution provides a means for monitoring intrahepatic virological events in chronic HBV infection. More important, our observations unravel the complexity of the HBV life cycle in vivo.
Xiaonan Zhang, Wei Lu, Ye Zheng, Weixia Wang, Lu Bai, Liang Chen, Yanling Feng, Zhanqing Zhang, Zhenghong Yuan
Simone Lanini, Gina Portella, Francesco Vairo, Gary P Kobinger, Antonio Pesenti, Martin Langer, Soccoh Kabia, Giorgio Brogiato, Jackson Amone, Concetta Castilletti, Rossella Miccio, Alimuddin Zumla, Maria Rosaria Capobianchi, Antonino Di Caro, Gino Strada, Giuseppe Ippolito, INMI-EMERGENCY EBOV Sierra Leone Study group
BACKGROUND. Ebola virus (EBOV) causes periodic outbreaks of life-threatening EBOV disease in Africa. Historically, these outbreaks have been relatively small and geographically contained; however, the magnitude of the EBOV outbreak that began in 2014 in West Africa has been unprecedented. The aim of this study was to describe the viral kinetics of EBOV during this outbreak and identify factors that contribute to outbreak progression.
METHODS. From July to December 2014, one laboratory in Sierra Leone processed over 2,700 patient samples for EBOV detection by quantitative PCR (qPCR). Viremia was measured following patient admission. Age, sex, and approximate time of symptom onset were also recorded for each patient. The data was analyzed using various mathematical models to find trends of potential interest.
RESULTS. The analysis revealed a significant difference (
CONCLUSIONS. Our results indicate that initial viremia is associated with outcome of the individual and outbreak duration; therefore, care must be taken in planning clinical trials and interventions. Additional research in virus adaptation and the impacts of host factors on EBOV transmission and pathogenesis is needed.
Marc-Antoine de La Vega, Grazia Caleo, Jonathan Audet, Xiangguo Qiu, Robert A. Kozak, James I. Brooks, Steven Kern, Anja Wolz, Armand Sprecher, Jane Greig, Kamalini Lokuge, David K. Kargbo, Brima Kargbo, Antonino Di Caro, Allen Grolla, Darwyn Kobasa, James E. Strong, Giuseppe Ippolito, Michel Van Herp, Gary P. Kobinger
For hepatitis C virus (HCV) and other highly variable viruses, broadly neutralizing mAbs are an important guide for vaccine development. The development of resistance to anti-HCV mAbs is poorly understood, in part due to a lack of neutralization testing against diverse, representative panels of HCV variants. Here, we developed a neutralization panel expressing diverse, naturally occurring HCV envelopes (E1E2s) and used this panel to characterize neutralizing breadth and resistance mechanisms of 18 previously described broadly neutralizing anti-HCV human mAbs. The observed mAb resistance could not be attributed to polymorphisms in E1E2 at known mAb-binding residues. Additionally, hierarchical clustering analysis of neutralization resistance patterns revealed relationships between mAbs that were not predicted by prior epitope mapping, identifying 3 distinct neutralization clusters. Using this clustering analysis and envelope sequence data, we identified polymorphisms in E2 that confer resistance to multiple broadly neutralizing mAbs. These polymorphisms, which are not at mAb contact residues, also conferred resistance to neutralization by plasma from HCV-infected subjects. Together, our method of neutralization clustering with sequence analysis reveals that polymorphisms at noncontact residues may be a major immune evasion mechanism for HCV, facilitating viral persistence and presenting a challenge for HCV vaccine development.
Justin R. Bailey, Lisa N. Wasilewski, Anna E. Snider, Ramy El-Diwany, William O. Osburn, Zhenyong Keck, Steven K.H. Foung, Stuart C. Ray
Unlike other picornaviruses, hepatitis A virus (HAV) is cloaked in host membranes when released from cells, providing protection from neutralizing antibodies and facilitating spread in the liver. Acute HAV infection is typified by minimal type I IFN responses; therefore, we questioned whether plasmacytoid dendritic cells (pDCs), which produce IFN when activated, are capable of sensing enveloped virions (eHAV). Although concentrated nonenveloped virus failed to activate freshly isolated human pDCs, these cells produced substantial amounts of IFN-α via TLR7 signaling when cocultured with infected cells. pDCs required either close contact with infected cells or exposure to concentrated culture supernatants for IFN-α production. In isopycnic and rate-zonal gradients, pDC-activating material cosedimented with eHAV but not membrane-bound acetylcholinesterase, suggesting that eHAV, and not viral RNA exosomes, is responsible for IFN-α induction. pDC activation did not require virus replication and was associated with efficient eHAV uptake, which was facilitated by phosphatidylserine receptors on pDCs. In chimpanzees, pDCs were transiently recruited to the liver early in infection, during or shortly before maximal intrahepatic IFN-stimulated gene expression, but disappeared prior to inflammation onset. Our data reveal that, while membrane envelopment protects HAV against neutralizing antibody, it also facilitates an early but limited detection of HAV infection by pDCs.
Zongdi Feng, You Li, Kevin L. McKnight, Lucinda Hensley, Robert E. Lanford, Christopher M. Walker, Stanley M. Lemon
Successful hepatitis C virus (HCV) treatment is defined as the absence of viremia 6 months after therapy cessation. We previously reported that trace amounts of HCV RNA, below the sensitivity of the standard clinical assay, can reappear sporadically in treatment responders. Here, we assessed the infectivity of this RNA and infused 3 chimpanzees sequentially at 9-week intervals with plasma or PBMCs from patients who tested positive for trace amounts of HCV RNA more than 6 months after completing pegylated IFN-α/ribavirin therapy. A fourth chimpanzee received HCV RNA–negative plasma and PBMCs from healthy blood donors. The 3 experimental chimpanzees, but not the control chimpanzee, generated HCV-specific T cell responses against nonstructural and structural HCV sequences 6–10 weeks after the first infusion of patient plasma and during subsequent infusions. In 1 chimpanzee, T cell responses declined, and this animal developed high-level viremia at week 27. Deep sequencing of HCV demonstrated transmission of a minor HCV variant from the first infusion donor that persisted in the chimpanzee for more than 6 months despite undetectable systemic viremia. Collectively, these results demonstrate that trace amounts of HCV RNA, which appear sporadically in successfully treated patients, can be infectious; furthermore, transmission can be masked in the recipient by an extended eclipse phase prior to establishing high-level viremia.
Naga Suresh Veerapu, Su-Hyung Park, Damien C. Tully, Todd M. Allen, Barbara Rehermann
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