Quantitative analysis of magnetic resonance images for characterization of blood-brain barrier dysfunction in dogs with brain tumors.

BACKGROUND: Blood-brain barrier (BBB) permeability can be assessed quantitatively using advanced imaging analysis. HYPOTHESIS/OBJECTIVES: Quantification and characterization of blood-brain barrier dysfunction (BBBD) patterns in dogs with brain tumors can provide useful information about tumor biology and assist in distinguishing between gliomas and meningiomas. ANIMALS: Seventy-eight hospitalized dogs with brain tumors and 12 control dogs without brain tumors. METHODS: In a 2-arm study, images from a prospective dynamic contrast-enhanced (DCE; n = 15) and a retrospective archived magnetic resonance imaging study (n = 63) were analyzed by DCE and subtraction enhancement analysis (SEA) to quantify BBB permeability in affected dogs relative to control dogs (n = 6 in each arm). For the SEA method, 2 ranges of postcontrast intensity differences, that is, high (HR) and low (LR), were evaluated as possible representations of 2 classes of BBB leakage. BBB score was calculated for each dog and was associated with clinical characteristics and tumor location and class. Permeability maps were generated, using the slope values (DCE) or intensity difference (SEA) of each voxel, and analyzed. RESULTS: Distinctive patterns and distributions of BBBD were identified for intra- and extra-axial tumors. At a cutoff of 0.1, LR/HR BBB score ratio yielded a sensitivity of 80% and specificity of 100% in differentiating gliomas from meningiomas. CONCLUSIONS AND CLINICAL IMPORTANCE: Blood-brain barrier dysfunction quantification using advanced imaging analyses has the potential to be used for assessment of brain tumor characteristics and behavior and, particularly, to help differentiating gliomas from meningiomas.

Virus detection in high-throughput sequencing data without a reference genome of the host.

Discovery of novel viruses in host samples is a multidisciplinary process which relies increasingly on next-generation sequencing (NGS) followed by computational analysis. A crucial step in this analysis is to separate host sequence reads from the sequence reads of the virus to be discovered. This becomes especially difficult if no reference genome of the host is available. Furthermore, if the total number of viral reads in a sample is low, de novo assembly of a virus which is a requirement for most existing pipelines is hard to realize. We present a new modular, computational pipeline for discovery of novel viruses in host samples. While existing pipelines rely on the availability of the hosts reference genome for filtering sequence reads, our new pipeline can also cope with cases for which no reference genome is available. As a further novelty of our method a decoy module is used to assess false classification rates in the discovery process. Additionally, viruses with a low read coverage can be identified and visually reviewed. We validate our pipeline on simulated data as well as two experimental samples with known virus content. For the experimental samples, we were able to reproduce the laboratory findings. Our newly developed pipeline is applicable for virus detection in a wide range of host species. The three modules we present can either be incorporated individually in other pipelines or be used as a stand-alone pipeline. We are the first to present a decoy approach within a virus detection pipeline that can be used to assess error rates so that the quality of the final result can be judged. We provide an implementation of our modules via Github. However, the principle of the modules can easily be re-implemented by other researchers.

Vertical transmission of hepatitis C virus-like non-primate hepacivirus in horses.

Non-primate hepacivirus (NPHV), a recently discovered hepatotropic virus infecting horses, is phylogenetically the closest known homologue of hepatitis C virus (HCV). The main route for acquiring HCV infection in childhood is vertical transmission. However, nothing is known about the natural mode of transmission for NPHV. To investigate the possibility of vertically transmitted NPHV infection in horses, 20 Thoroughbred broodmares and their foals were monitored during foaling season 2015 until 6 months post-partum. Prepartal serum was taken from the mares, and during foaling umbilical cord blood and colostrum samples were collected. Postnatal serum samples were taken from the foals after delivery. In addition, serum was taken at 3 and 6 months after foaling from all mares and foals. Samples were analysed for the presence of NPHV RNA by quantitative real-time PCR and for the presence of anti-NPHV NS3 antibodies by luciferase immunoprecipitation system. Identified NPHV isolates were sequenced and phylogenetic analysis of the viral glycoproteins was used to track the course of naturally occurring infections and the circulation of distinct isolates within the herd. At parturition, 16 mares were seropositive, including four viraemic mares. Vertical transmission occurred in one of these four mare-foal pairs. Interestingly, NPHV isolates of newly infected foals and mares after 3 and 6 months cluster in their respective pasture herds suggesting another horizontal route of transmission.

Prevalence of Hepatitis E virus-specific antibodies in sera of German domestic pigs estimated by using different assays.

Hepatitis E virus is the causative agent of an acute hepatitis in humans. In industrialized countries, autochthonous hepatitis E cases in the past were mainly of undetermined origin, whereupon nowadays some cases may be linked to zoonotic transmission of HEV from pigs and wild boars. In contrast to several European countries the HEV status of German domestic pigs and a possible risk of transmission are unknown so far. Here, a novel peptide-based ELISA was used to detect HEV-specific antibodies in 1072 sera from German domestic pigs resulting in an average seroprevalence of 49.8% indicating widespread HEV infections in these animals. A comparative testing of 321 randomly selected sera revealed a seroprevalence of 64.8% when using a commercially available ELISA and 43.9% for the novel peptide-based ELISA but concordant results were obtained in both tests only for 56.1% of the sera. Additional re-testing of 23 randomly selected sera with a modified commercially available immunoblot revealed discordant results also. The use of different antigens and the measurement of different immunoglobulin classes are considered to be responsible for the observed variations of the results. Though the present study revealed a high seroprevalence of HEV in the German domestic pig population and a potential risk of transmission to humans, the differing results of the tests highlight the necessity of a standardization of serological assays for comparative seroprevalence and longitudinal studies.

Hepatitis E virus infection as a cause of graft hepatitis in liver transplant recipients.

Hepatitis E virus (HEV) infection induces self-limiting liver disease in immunocompetent individuals. Cases of chronic hepatitis E have recently been identified in organ transplant recipients. We questioned if chronic hepatitis E plays a role in graft hepatitis after liver transplantation in a low endemic area. Two hundred twenty-six liver transplant recipients, 129 nontransplanted patients with chronic liver disease, and 108 healthy controls were tested for HEV antibodies. HEV RNA was investigated in all sera from transplanted patients. HEV antibodies were detected in 1 healthy control (1%), 4 patients with chronic liver disease (3%), and 10 liver transplant recipients (4%). Three liver transplant patients also tested positive for HEV RNA. Two of them developed persistent viremia with HEV genotype 3. The patients were anti-HEV immunoglobulin G-negative and HEV RNA-negative before transplantation and had an episode of acute hepatitis 5 or 7 months after transplantation, which led to advanced liver fibrosis after 22 months in 1 patient. Seroconversion to anti-HEV occurred not before 4 months after the first detection of HEV RNA. The possibility of reverse zoonotic transmission was experimentally confirmed by the infection of 5 pigs with a patient's serum. The pigs showed histological inflammation in the liver, and HEV RNA was detectable in different organs, including muscle. In conclusion, the prevalence of HEV infection in Central European liver transplant recipients is low; however, chronic hepatitis E may occur and needs to be considered in the differential diagnosis of graft hepatitis. The diagnosis of HEV infection should be based on HEV RNA determination in immunosuppressed patients. We suggest that immunocompromised individuals should avoid eating uncooked meat and contact with possibly HEV-infected animals.

Retrospective study on the occurrence of porcine circovirus 2 infection and associated entities in Northern Germany.

Porcine circovirus type 2 (PCV 2) represents a widespread, globally occurring pathogen with an increasing number of associated entities. To further elucidate the origin, spread and pathogenesis of PCV2 and associated changes archived material of pigs originating from Northern Germany and submitted for necropsy between 1961 and 1998 were investigated by using in situ hybridisation and polymerase chain reaction. PCV2 was first detected in a pig from 1962. However, incidence of detectable viral DNA and occurrence of PCV2-associated lesions varied substantially in the following years. The overall incidence of PCV2 infection was low between 1961 and 1984 (0-11.7%) and increased between 1985 and 1998 (14.3-53.3%). PCV2-associated pathological changes including postweaning multisystemic wasting syndrome (PMWS) and most likely porcine dermatitis and nephropathy syndrome (PDNS) were first observed in 1985. Selected sequence analyses of PCV2 DNA segments revealed high homology with current virus strains. In summary, findings showed that PCV2 has been present in the pig population in Northern Germany since 1962. This represents worldwide the earliest report about the detection of the PCV2 genome in pigs. Associated lesions such as PMWS and PDNS were not observed before 1985, indicating that virus infection alone does not seem to be sufficient enough to trigger the development of associated entities. Limited sequence analysis revealed no changes in the viral genome thus suggesting that other factors including environmental changes or co-infections with other agents might play a contributing role in the altered virulence of this pathogen and the occurrence of PCV2-associated lesions.