Marburg and Ebola Virus Infections Elicit a Complex, Muted Inflammatory State in Bats

The Marburg and Ebola filoviruses cause a severe, often fatal, disease in humans and nonhuman primates but have only subclinical effects in bats, including Egyptian rousettes, which are a natural reservoir of Marburg virus. A fundamental question is why these viruses are highly pathogenic in humans but fail to cause disease in bats. To address this question, we infected one cohort of Egyptian rousette bats with Marburg virus and another cohort with Ebola virus and harvested multiple tissues for mRNA expression analysis. While virus transcripts were found primarily in the liver, principal component analysis (PCA) revealed coordinated changes across multiple tissues. Gene signatures in kidney and liver pointed at induction of vasodilation, reduction in coagulation, and changes in the regulation of iron metabolism. Signatures of immune response detected in spleen and liver indicated a robust anti-inflammatory state signified by macrophages in the M2 state and an active T cell response. The evolutionary divergence between bats and humans of many responsive genes might provide a framework for understanding the differing outcomes upon infection by filoviruses. In this study, we outline multiple interconnected pathways that respond to infection by MARV and EBOV, providing insights into the complexity of the mechanisms that enable bats to resist the disease caused by filoviral infections. The results have the potential to aid in the development of new strategies to effectively mitigate and treat the disease caused by these viruses in humans.

3D sub-nanometer analysis of glucose in an aqueous solution by cryo-atom probe tomography

Atom Probe Tomography (APT) is currently a well-established technique to analyse the composition of solid materials including metals, semiconductors and ceramics with up to near-atomic resolution. Using an aqueous glucose solution, we now extended the technique to frozen solutions. While the mass signals of the common glucose fragments C_xH_y and C_xO_yH_z overlap with (H₂O)_nH from water, we achieved stoichiometrically correct values via signal deconvolution. Density functional theory (DFT) calculations were performed to investigate the stability of the detected pyranose fragments. This paper demonstrates APT’s capabilities to achieve sub-nanometre resolution in tracing whole glucose molecules in a frozen solution by using cryogenic workflows. We use a solution of defined concentration to investigate the chemical resolution capabilities as a step toward the measurement of biological molecules. Due to the evaporation of nearly intact glucose molecules, their position within the measured 3D volume of the solution can be determined with sub-nanometre resolution. Our analyses take analytical techniques to a new level, since chemical characterization methods for cryogenically-frozen solutions or biological materials are limited.

Field evaporation and atom probe tomography of pure water tips

Measuring biological samples by atom probe tomography (APT) in their natural environment, i.e. aqueous solution, would take this analytical method, which is currently well established for metals, semi-conductive materials and non-metals, to a new level. It would give information about the 3D chemical structure of biological systems, which could enable unprecedented insights into biological systems and processes, such as virus protein interactions. For this future aim, we present as a first essential step the APT analysis of pure water (Milli-Q) which is the main component of biological systems. After Cryo-preparation, nanometric water tips are field evaporated with assistance by short laser pulses. The obtained data sets of several tens of millions of atoms reveal a complex evaporation behavior. Understanding the field evaporation process of water is fundamental for the measurement of more complex biological systems. For the identification of the individual signals in the mass spectrum, DFT calculations were performed to prove the stability of the detected molecules.

Protein Interaction Mapping Identifies RBBP6 as a Negative Regulator of Ebola Virus Replication

Ebola virus (EBOV) infection often results in fatal illness in humans, yet little is known about how EBOV usurps host pathways during infection. To address this, we used affinity tag-purification mass spectrometry (AP-MS) to generate an EBOV-host protein-protein interaction (PPI) map. We uncovered 194 high-confidence EBOV-human PPIs, including one between the viral transcription regulator VP30 and the host ubiquitin ligase RBBP6. Domain mapping identified a 23 amino acid region within RBBP6 that binds to VP30. A crystal structure of the VP30-RBBP6 peptide complex revealed that RBBP6 mimics the viral nucleoprotein (NP) binding to the same interface of VP30. Knockdown of endogenous RBBP6 stimulated viral transcription and increased EBOV replication, whereas overexpression of either RBBP6 or the peptide strongly inhibited both. These results demonstrate the therapeutic potential of biologics that target this interface and identify additional PPIs that may be leveraged for novel therapeutic strategies.

Abstract P3-13-02: Surcigal management of ipsilateral breast tumor recurrence

PURPOSE

Approximately 10-15% of breast cancer patients treated by breast conserving surgery (BCS) and adjuvant radiotherapy (RT) will develop ipsilateral breast tumor recurrence (IBTR).

International guidelines suggest total mastectomy as treatment of choice for IBTR following lumpectomy and RT. Nevertheless, there is evidence that second BCS might be equally sufficient.

PATIENTS AND METHODS

Patients with IBTR diagnosed between 1990 and 2014 after BCS and RT were included (n=170).

34.1% women underwent secondary BCS, whereas 65.9% were treated by mastectomy. We determined predictive factors for time to local progression (TTP), disease free survival (DFS), and overall survival (OS) comparing these two groups.

RESULTS

Median follow-up after primary IBTR was 49 months (59 months for patients still alive at time of analysis). Five-year IBTR-free rate after secondary BCS was 77.6% (SD±6.1%) and 75.0% (SD±4.5%) for patients after mastectomy. Five-year DFS was 57.3% (SD±8.2%), and 61.9% (SD±5.5%), five-year OS was 84.7% (SD±5.8%), and 72.6% (SD±5.1%), respectively.

Prior adjuvant systemic therapy, muscular invasion, and skin infiltration were independent significant risk factors for a shorter TTP.

Additionally, lymphovascular infiltration (LVI) in the IBTR increased the risk for a shorter DFS.

LVI, muscular invasion, and skin infiltration were identified as independent significant risk factors for a shorter OS.

CONCLUSION

No significant difference in local control, DFS, and OS was seen between IBTR patients treated either by secondary BCS or mastectomy. Our data suggest that secondary BCS for IBTR patients after initial BCS and RT is feasible in selected patients.

Citation Format: Kolben T, Schwarz TM, Goess C, Blume C, Degenhardt T, Engel J, Wuerstlein R, Ditsch N, Harbeck N, Kahlert S. Surcigal management of ipsilateral breast tumor recurrence. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-13-02.

Long ncRNAs expressed during human cytomegalovirus infections

ABSTRACT: 

Human cytomegalovirus (HCMV) has a tremendous coding capacity within its dsDNA genome that has allowed it to coevolve with its host. Transcription of the virus genome is not limited to protein-coding genes; in fact, most of the transcription from the HCMV genome during lytic replication generates viral ncRNAs that are not translated into protein. Four long ncRNAs (RNA5.0, RNA4.9, RNA1.2 and RNA2.7) account for the majority of HCMV transcription during lytic replication. Here, we review the expression and function of these long ncRNAs in the context of virus replication and pathogenesis. Long ncRNAs may contribute to HCMV evasion of the host response and manipulate cellular and viral programs to successfully persist throughout the lifetime of its host.

Molecular investigation of the 7.2 kb RNA of murine cytomegalovirus

Background

HCMV encodes a stable 5 kb RNA of unknown function that is conserved across cytomegalovirus species. In vivo studies of the MCMV orthologue, a 7.2 kb RNA, demonstrated that viruses that do not express the RNA fail to establish efficient persistent replication in the salivary glands of mice. To gain further insight into the function and properties of this conserved locus, we characterized the MCMV intron in finer detail.

Methods

We performed multiple analyses to evaluate transcript expression kinetics, identify transcript termini and promoter elements. The half-lives of intron locus RNAs were quantified by measuring RNA levels following actinomycin D treatment in a qRT-PCR-based assay. We also constructed a series of recombinant viruses to evaluate protein coding potential in the locus and test the role of putative promoter elements. These recombinant viruses were tested in both in vitro and in vivo assays.

Results

We show that the 7.2 kb RNA is expressed with late kinetics during productive infection of mouse fibroblasts. The termini of the precursor RNA that is processed to produce the intron were identified and we demonstrate that the m106 open reading frame, which resides on the spliced mRNA derived from precursor processing, can be translated during infection. Mapping the 5′ end of the primary transcript revealed minimal promoter elements located upstream that contribute to transcript expression. Analysis of recombinant viruses with deletions in the putative promoter elements, however, revealed these elements exert only minor effects on intron expression and viral persistence in vivo. Low transcriptional output by the putative promoter element(s) is compensated by the long half-life of the 7.2 kb RNA of approximately 28.8 hours. Detailed analysis of viral spread prior to the establishment of persistence also showed that the intron is not likely required for efficient spread to the salivary gland, but rather enhances persistent replication in this tissue site.

Conclusions

This data provides a comprehensive transcriptional analysis of the MCMV 7.2 kb intron locus. Our studies indicate that the 7.2 kb RNA is an extremely long-lived RNA, a feature which is likely to be important in its role promoting viral persistence in the salivary gland.