Persistent viremia by a novel parvovirus in a slow loris (Nycticebus coucang) with diffuse histiocytic sarcoma

Small but mighty: old and new parvoviruses of veterinary significance

In line with the Latin expression "sed parva forti" meaning "small but mighty," the family Parvoviridae contains many of the smallest known viruses, some of which result in fatal or debilitating infections. In recent years, advances in metagenomic viral discovery techniques have dramatically increased the identification of novel parvoviruses in both diseased and healthy individuals. While some of these discoveries have solved etiologic mysteries of well-described diseases in animals, many of the newly discovered parvoviruses appear to cause mild or no disease, or disease associations remain to be established. With the increased use of animal parvoviruses as vectors for gene therapy and oncolytic treatments in humans, it becomes all the more important to understand the diversity, pathogenic potential, and evolution of this diverse family of viruses. In this review, we discuss parvoviruses infecting vertebrate animals, with a special focus on pathogens of veterinary significance and viruses discovered within the last four years.

Viral Metagenomics on Cerebrospinal Fluid

Identifying the causative pathogen in central nervous system (CNS) infections is crucial for patient management and prognosis. Many viruses can cause CNS infections, yet screening for each individually is costly and time-consuming. Most metagenomic assays can theoretically detect all pathogens, but often fail to detect viruses because of their small genome and low viral load. Viral metagenomics overcomes this by enrichment of the viral genomic content in a sample. VIDISCA-NGS is one of the available workflows for viral metagenomics, which requires only a small input volume and allows multiplexing of multiple samples per run. The performance of VIDISCA-NGS was tested on 45 cerebrospinal fluid (CSF) samples from patients with suspected CNS infections in which a virus was identified and quantified by polymerase chain reaction. Eighteen were positive for an RNA virus, and 34 for a herpesvirus. VIDISCA-NGS detected all RNA viruses with a viral load >2 × 104 RNA copies/mL (n = 6) and 8 of 12 of the remaining low load samples. Only one herpesvirus was identified by VIDISCA-NGS, however, when withholding a DNase treatment, 11 of 18 samples with a herpesvirus load >104 DNA copies/mL were detected. Our results indicate that VIDISCA-NGS has the capacity to detect low load RNA viruses in CSF. Herpesvirus DNA in clinical samples is probably non-encapsidated and therefore difficult to detect by VIDISCA-NGS.

Molecular Characterization and Evolutionary Analyses of Carnivore Protoparvovirus 1 NS1 Gene

Carnivore protoparvovirus 1 is the etiological agent of a severe disease of terrestrial carnivores. This unique specie encompasses canine parvovirus type 2 (CPV-2) and feline panleukopenia virus (FPLV). Studies widely analyzed the main capsid protein (VP2), but limited information is available on the nonstructural genes (NS1/NS2). This paper analyzed the NS1 gene sequence of FPLV and CPV strains collected in Italy in 2009–2017, along with worldwide related sequences. Differently from VP2, only one NS1 amino-acid residue (248) clearly and constantly distinguished FPLV from CPV-2, while five possible convergent amino-acid changes were observed that may affect the functional domains of the NS1. Some synonymous mutation in NS1 were non-synonymous in NS2 and vice versa. No evidence for recombination between the two lineages was found, and the predominance of negative selection pressure on NS1 proteins was observed, with low and no overlap between the two lineages in negatively and positively selected codons, respectively. More sites were under selection in the CPV-2 lineage. NS1 phylogenetic analysis showed divergent evolution between FPLV and CPV, and strains were clustered mostly by country and year of detection. We highlight the importance of obtaining the NS1/NS2 coding sequence in molecular epidemiology investigations.

Putative histiocytic sarcoma in redfin needlefish Strongylura notata (Beloniformes: Belonidae) in Florida, USA

Redfin needlefish Strongylura notata from Florida coastal waters were observed with unusual neoplastic lesions. Affected specimens were collected from 1 Atlantic estuary (Indian River Lagoon, prevalence = 0.32%, n = 5314) and 2 Gulf of Mexico estuaries (Tampa Bay, prevalence = 0.02%, n = 10762; Charlotte Harbor, prevalence = 0.02%, n = 5112) during routine fisheries-independent monitoring surveys conducted from 1999-2009. Grossly, each lesion manifested as a large (18-30 mm × 20-50 mm), raised (approximately 10 mm), white, creamy, or pinkish nodule on the flank, dorsal trunk, base of the pectoral fin, or head. Multiple small (<5 mm) nodules possessing poorly demarcated borders with neighboring tissues on the external jaw surface and at the base of the teeth were also observed. Histopathologically, neoplastic cells were found in the dermis, beneath the skeletal muscle, and in the soft tissue at the base of teeth of the premaxilla and the dentary jaw processes. Neoplastic cells usually had prominently invaded among the myosepta of the skeletal muscle. Neoplastic parenchymal cells had the basic characteristics of atypical, mononuclear, round, histiocytic cells with an eccentric, reniform nucleus and abundant cytoplasmic vacuolation, while some exhibited bizarre nuclear pleomorphism. Transmission electron microscopy revealed that neoplastic cells had a grooved nucleus and cytoplasmic organelles with rough endoplasmic reticulum, mitochondria, Golgi apparatus, and lysosomes. Neoplastic cells had possibly metastasized to liver, spleen, and kidney. Positive immunohistochemical staining with Ki67, p53, S-100, and CD163 support neoplastic features and a putative diagnosis of histiocytic sarcoma.

Virus discovery reveals frequent infection by diverse novel members of the Flaviviridae in wild lemurs

Lemurs are highly endangered mammals inhabiting the forests of Madagascar. In this study, we performed virus discovery on serum samples collected from 84 wild lemurs and identified viral sequence fragments from 4 novel viruses within the family Flaviviridae, including members of the genera Hepacivirus and Pegivirus. The sifaka hepacivirus (SifHV, two genotypes) and pegivirus (SifPgV, two genotypes) were discovered in the diademed sifaka (Propithecus diadema), while other pegiviral fragments were detected in samples from the indri (Indri indri, IndPgV) and the weasel sportive lemur (Lepilemur mustelinus, LepPgV). Although data are preliminary, each viral species appeared host species-specific and frequent infection was detected (18 of 84 individuals were positive for at least one virus). The complete coding sequence and partial 5' and 3' untranslated regions (UTRs) were obtained for SifHV and its genomic organization was consistent with that of other hepaciviruses, with one unique polyprotein and highly structured UTRs. Phylogenetic analyses showed the SifHV belonged to a clade that includes several viral species identified in rodents from Asia and North America, while SifPgV and IndPgV were more closely related to pegiviral species A and C, that include viruses found in humans as well as New- and Old-World monkeys. Our results support the current proposed model of virus-host co-divergence with frequent occurrence of cross-species transmission for these genera and highlight how the discovery of more members of the Flaviviridae can help clarify the ecology and evolutionary history of these viruses. Furthermore, this knowledge is important for conservation and captive management of lemurs.

Association of the Human Bocavirus With Tonsil Squamous Cell Carcinomas

Background: The human bocavirus (HBoV) is known to persist latently in the infected host cells and seems to replicate its DNA via the DNA damage response system, which is frequently defect in tumors and correlates with microsatellite instability (MSI). Because HBoV is able to persist in the infected tissues, induces pro-fibrotic and pro- cancerogenic cytokines in vivo and in vitro, and is detected in colorectal and lung tumors, the virus may be involved in cancerogenesis at least as a cofactor. Recently it was shown that the adenotonsillar tissue is an important site of HBoV1 persistence and replication. Considering the background that approximately 60% of oropharyngeal cancers were thought to be attributable to a HPV infection, a co-participation of HBoV in terms of a chronic virus infection might play a role in the cancerogenesis of tonsil tumors.

Methods: Formalin-fixed, paraffin-embedded tonsil tumor samples were screened for HBoV and HPV DNA. Positive tissue sections were afterward subjected to fluorescence in situ hybridization (FISH) analysis to identify HBoV and HPV infected cells. By use of an in vitro cell culture model with primary tonsil fibroblasts, keratinocytes, and lymphocytes infected by HBoV we tried to find the target cells of virus replication. MSI testing was based on a previously published protocol using a de-multiplexed PCR followed by fluorescent detection of PCR products in a capillary sequencing device.

Results: In total 62 of 103 (60, 19%) of the tonsil squamous cell carcinomas tested positive for HBoV DNA and 66 of 103 (66%) samples were identified as HPV positive. The FISH analysis revealed both double infection of HPV and HBoV in the same cells as well as single infections of both viruses within the tumor tissue. Twenty-two of 62 HBoV positive tumors tested HPV negative, 40 of 62 tissue sections were HBoV and HPV positive. We analyzed 21 out of the 62 HBoV positive tumors for MSI. Of those four tonsils displayed MSI in at least 1 of 10 microsatellite markers.

Conclusion: Our findings support the hypothesis that human bocavirus infections as a cofactor may have an impact on tumor development in tonsils, although it still remains possible that HBoV solely displays a tumor tropism.

SYSTEMIC HISTIOCYTIC SARCOMA IN A COMMON HIPPOPOTAMUS (HIPPOPOTAMUS AMPHIBIUS)

A 37-yr-old captive common hippopotamus (Hippopotamus amphibius) developed lethargy and decline in mobility that progressed to death, despite supportive therapy. Histopathologic examination revealed severe, diffuse, intravascular and interstitial infiltration of neoplastic histiocytes in the spleen, liver, lymph nodes, lungs, large intestine, kidneys, and thyroid gland. Neoplastic cells were pleomorphic with marked anisocytosis and anisokaryosis, scattered multinucleated giant cells, numerous bizarre mitotic figures, and marked erythrophagocytosis. Immunohistochemistry demonstrated that neoplastic cells were positive for ionized calcium-binding adapter molecule 1 (a histiocytic marker) and negative for CD3 (a T-cell marker) and myeloperoxidase, confirming the diagnosis of systemic histiocytic sarcoma.

Viral metagenomics and blood safety

The characterization of the human blood-associated viral community (also called blood virome) is essential for epidemiological surveillance and to anticipate new potential threats for blood transfusion safety. Currently, the risk of blood-borne agent transmission of well-known viruses (HBV, HCV, HIV and HTLV) can be considered as under control in high-resource countries. However, other viruses unknown or unsuspected may be transmitted to recipients by blood-derived products. This is particularly relevant considering that a significant proportion of transfused patients are immunocompromised and more frequently subjected to fatal outcomes. Several measures to prevent transfusion transmission of unknown viruses have been implemented including the exclusion of at-risk donors, leukocyte reduction of donor blood, and physicochemical treatment of the different blood components. However, up to now there is no universal method for pathogen inactivation, which would be applicable for all types of blood components and, equally effective for all viral families. In addition, among available inactivation procedures of viral genomes, some of them are recognized to be less effective on non-enveloped viruses, and inadequate to inactivate higher viral titers in plasma pools or derivatives. Given this, there is the need to implement new methodologies for the discovery of unknown viruses that may affect blood transfusion. Viral metagenomics combined with High Throughput Sequencing appears as a promising approach for the identification and global surveillance of new and/or unexpected viruses that could impair blood transfusion safety.

Driving forces behind the evolution of the Aleutian mink disease parvovirus in the context of intensive farming

Aleutian mink disease virus (AMDV) causes plasmacytosis, an immune complex-associated syndrome that affects wild and farmed mink. The virus can also infect other small mammals (e.g., ferrets, skunks, ermines, and raccoons), but the disease in these hosts has been studied less. In 2007, a mink plasmacytosis outbreak began on the Island of Newfoundland, and the virus has been endemic in farms since then. In this study, we evaluated the molecular epidemiology of AMDV in farmed and wild animals of Newfoundland since before the beginning of the outbreak and investigated the epidemic in a global context by studying AMDV worldwide, thereby examining its diffusion and phylogeography. Furthermore, AMDV evolution was examined in the context of intensive farming, where host population dynamics strongly influence viral evolution. Partial NS1 sequences and several complete genomes were obtained from Newfoundland viruses and analyzed along with numerous sequences from other locations worldwide that were either obtained as part of this study or from public databases. We observed very high viral diversity within Newfoundland and within single farms, where high rates of co-infection, recombinant viruses and polymorphisms were observed within single infected individuals. Worldwide, we documented a partial geographic distribution of strains, where viruses from different countries co-exist within clades but form country-specific subclades. Finally, we observed the occurrence of recombination and the predominance of negative selection pressure on AMDV proteins. A surprisingly low number of immunoepitopic sites were under diversifying pressure, possibly because AMDV gains no benefit by escaping the immune response as viral entry into target cells is mediated through interactions with antibodies, which therefore contribute to cell infection. In conclusion, the high prevalence of AMDV in farms facilitates the establishment of co-infections that can favor the occurrence of recombination and enhance viral diversity. Viruses are then exchanged between different farms and countries and can be introduced into the wild, with the rapidly evolving viruses producing many parallel lineages.

Viral metagenomics in drug-naïve, first-onset schizophrenia patients with prominent negative symptoms

Although several studies suggest a virus or (endogenous) retrovirus involvement at the time of onset of schizophrenia, the unequivocal identification of one or more infectious agents, by means of an undirected catch-all technique, has never been conducted. In this study VIDISCA, a virus discovery method, was used in combination with Roche-454 high-throughput sequencing as a tool to determine the possible presence of viruses (known or unknown) in blood of first-onset drugs-naïve schizophrenic patients with prominent negative symptoms. Two viruses (the Anellovirus Torque Teno virus and GB virus C) were detected. Both viruses are commonly found in healthy individuals and no clear link with disease was ever established. Viruses from the family Anelloviridae were also identified in the control population (4.8%). Besides, one patient sample was positive for human endogenous retroviruses type K (HML-2) RNA but no specific predominant strain was detected, instead 119 different variants were found. In conclusion, these findings indicate no evidence for viral or endogenous retroviral involvement in sera at the time of onset of schizophrenia.

Reduced maternal levels of common viruses during pregnancy predict offspring psychosis: potential role of enhanced maternal immune activity?

Viral infections during the prenatal or early childhood periods are one of the environmental factors which might play an etiological role in psychoses. Several studies report higher antibody levels against viruses during pregnancy in blood of mothers of offspring with psychotic disorders, but the presence of such viruses has never been demonstrated. The goal of this study was to investigate the potential association between viral infections during pregnancy and progeny with psychotic disorders and, for this purpose, we performed a nested case-control study involving pregnant mothers of offspring with schizophrenia or bipolar disorder with psychotic features (cases, N=43) and pregnant women with healthy offspring (controls, N=95). Since several potential viral candidates have been suggested in prior work, a broad-spectrum virus detection system was necessary. A metagenomic analysis performed with the virus discovery method VIDISCA-454 revealed only common blood-associated viruses in all cohorts. However, a significantly lower viral prevalence was detected in the group of cases and in the sub-population of pregnant mothers of offspring with schizophrenia (p<0.05). Consistent with the existing inverse correlation between the level of these viruses and the immunocompetence of an individual, we hypothesized the presence of a higher immune activity during pregnancy in mothers whose offspring later develop a psychotic disorder as compared to controls. Combining our results with previously available literature data on antibody levels during the gestation period suggests that a more prominent maternal immune activity can be considered a risk factor for developing psychosis.