Infection with Pythium flevoense in a harbour porpoise (Phocoena phocoena) as a novel cause of dermatitis in marine mammals.

The oomycete Pythium flevoense was diagnosed as the cause of dermatitis in a young adult female harbour porpoise (Phocoena phocoena) that had been trapped in a pound net in a temperate saltwater environment. Disease from Pythium sp. infection-pythiosis-is infrequently diagnosed in humans, horses, dogs, cattle, and few other mammalian species. Pythiosis is typically associated with exposure to tropical or subtropical freshwater conditions, and typically caused by Pythium insidiosum. However, until now, pythiosis has been reported in neither marine mammals nor temperate saltwater conditions, and P. flevoense is not known as a cause of pythiosis in mammals. This porpoise developed generalised dermatitis despite treatment and euthanasia was necessary. Histopathological evaluation revealed a chronic active erosive dermatitis, with intralesional hyphae morphologically consistent with a Pythium sp. PCR analysis and sequencing of affected skin matched Pythium flevoense with a 100% similarity to the reference strain. Additional diagnostics excluded other pathogens. Based on this case report, P. flevoense needs to be considered as a mammalian pathogen. Furthermore, harbour porpoises and possibly other marine mammals may be at risk of infection with P. flevoense, and pythiosis should be included in the differential diagnosis of dermatitis in marine mammals.

In vivo comparison of a laboratory-adapted and clinical-isolate-based recombinant human respiratory syncytial virus.

Human respiratory syncytial virus (HRSV) is the leading cause of severe respiratory tract disease in infants. Most HRSV infections remain restricted to the upper respiratory tract (URT), but in a small percentage of patients the infection spreads to the lower respiratory tract, resulting in bronchiolitis or pneumonia. We have a limited understanding of HRSV pathogenesis and what factors determine disease severity, partly due to the widespread use of tissue-culture-adapted viruses. Here, we studied early viral dissemination and tropism of HRSV in cotton rats, BALB/cJ mice and C57BL/6 mice. We used a novel recombinant (r) strain based on a subgroup A clinical isolate (A11) expressing EGFP [rHRSVA11EGFP(5)]. A recombinant laboratory-adapted HRSV strain [rHRSVA2EGFP(5)] was used as a direct comparison. Our results show that rHRSVA11EGFP(5) replicated to higher viral titres than laboratory-adapted rHRSVA2EGFP(5) in the URT of cotton rats and mice. HRSV-infected cells were detected as early as 2 days post-inoculation in both species in the nasal septa and lungs. Infection was predominantly present in ciliated epithelial cells in cotton rats and in the olfactory mucosa of mice. In our opinion, this study highlights that the choice of virus strain is important when studying HRSV pathogenesis in vivo and demonstrates that A11 is a representative clinical-based virus. Additionally, we show critical differences in tropism and inflammation when comparing HRSV infection of cotton rats and mice.

Delineating morbillivirus entry, dissemination and airborne transmission by studying in vivo competition of multicolor canine distemper viruses in ferrets.

Identification of cellular receptors and characterization of viral tropism in animal models have vastly improved our understanding of morbillivirus pathogenesis. However, specific aspects of viral entry, dissemination and transmission remain difficult to recapitulate in animal models. Here, we used three virologically identical but phenotypically distinct recombinant (r) canine distemper viruses (CDV) expressing different fluorescent reporter proteins for in vivo competition and airborne transmission studies in ferrets (Mustela putorius furo). Six donor ferrets simultaneously received three rCDVs expressing green, red or blue fluorescent proteins via conjunctival (ocular, Oc), intra-nasal (IN) or intra-tracheal (IT) inoculation. Two days post-inoculation sentinel ferrets were placed in physically separated adjacent cages to assess airborne transmission. All donor ferrets developed lymphopenia, fever and lethargy, showed progressively increasing systemic viral loads and were euthanized 14 to 16 days post-inoculation. Systemic replication of virus inoculated via the Oc, IN and IT routes was detected in 2/6, 5/6 and 6/6 ferrets, respectively. In five donor ferrets the IT delivered virus dominated, although replication of two or three different viruses was detected in 5/6 animals. Single lymphocytes expressing multiple fluorescent proteins were abundant in peripheral blood and lymphoid tissues, demonstrating the occurrence of double and triple virus infections. Transmission occurred efficiently and all recipient ferrets showed evidence of infection between 18 and 22 days post-inoculation of the donor ferrets. In all cases, airborne transmission resulted in replication of a single-colored virus, which was the dominant virus in the donor ferret. This study demonstrates that morbilliviruses can use multiple entry routes in parallel, and co-infection of cells during viral dissemination in the host is common. Airborne transmission was efficient, although transmission of viruses expressing a single color suggested a bottleneck event. The identity of the transmitted virus was not determined by the site of inoculation but by the viral dominance during dissemination.

Clinical, pathological, and laboratory diagnoses of diseases of harbour porpoises (Phocoena phocoena), live stranded on the Dutch and adjacent coasts from 2003 to 2016.

Harbour porpoises (Phocoena phocoena) in the North Sea live in an environment heavily impacted by humans, the consequences of which are a concern for their health. Autopsies carried out on stranded harbour porpoises provide an opportunity to assess health problems in this species. We performed 61 autopsies on live-stranded harbour porpoises, which died following admission to a rehabilitation centre between 2003 and 2016. The animals had stranded on the Dutch (n = 52) and adjacent coasts of Belgium (n = 2) and Germany (n = 7). We assigned probable causes for stranding based on clinical and pathological criteria. Cause of stranding was associated in the majority of cases with pathologies in multiple organs (n = 29) compared to animals with pathologies in a single organ (n = 18). Our results show that the three most probable causes of stranding were pneumonia (n = 35), separation of calves from their mother (n = 10), and aspergillosis (n = 9). Pneumonia as a consequence of pulmonary nematode infection occurred in 19 animals. Pneumonia was significantly associated with infection with Pseudalius inflexus, Halocercus sp., and Torynurus convolutus but not with Stenurus minor infection. Half of the bacterial pneumonias (6/12) could not be associated with nematode infection. Conclusions from this study are that aspergillosis is an important probable cause for stranding, while parasitic infection is not a necessary prerequisite for bacterial pneumonia, and approximately half of the animals (29/61) probably stranded due to multiple causes. An important implication of the observed high prevalence of aspergillosis is that these harbour porpoises suffered from reduced immunocompetence.

Increased Protein Degradation Improves Influenza Virus Nucleoprotein-Specific CD8+ T Cell Activation In Vitro but Not in C57BL/6 Mice.

Due to antigenic drift of influenza viruses, seasonal influenza vaccines need to be updated annually. These vaccines are based on predictions of strains likely to circulate in the next season. However, vaccine efficacy is greatly reduced in the case of a mismatch between circulating and vaccine strains. Furthermore, novel antigenically distinct influenza viruses are introduced into the human population from animal reservoirs occasionally and may cause pandemic outbreaks. To dampen the impact of seasonal and pandemic influenza, vaccines that induce broadly protective and long-lasting immunity are preferred. Because influenza virus-specific CD8+ T cells are directed mainly against relatively conserved internal proteins, like nucleoprotein (NP), they are highly cross-reactive and afford protection against infection with antigenically distinct influenza virus strains, so-called heterosubtypic immunity. Here, we used modified vaccinia virus Ankara (MVA) as a vaccine vector for the induction of influenza virus NP-specific CD8+ T cells. To optimize the induction of CD8+ T cell responses, we made several modifications to NP, aiming at retaining the protein in the cytosol or targeting it to the proteasome. We hypothesized that these strategies would increase antigen processing and presentation and thus improve the induction of CD8+ T cell responses. We showed that NP with increased degradation rates improved CD8+ T cell activation in vitro if the amount of antigen was limited or if CD8+ T cells were of low functional avidity. However, after immunization of C57BL/6 mice, no differences were detected between modified NP and wild-type NP (NPwt), since NPwt already induced optimal CD8+ T cell responses. IMPORTANCE: Due to the continuous antigenic drift of seasonal influenza viruses and the threat of a novel pandemic, there is a great need for the development of novel influenza vaccines that offer broadly protective immunity against multiple subtypes. CD8+ T cells can provide immunity against multiple subtypes of influenza viruses by the recognition of relatively conserved internal antigens. In this study, we aimed at optimizing the CD8+ T cell response to influenza A virus by making modifications to influenza A virus nucleoprotein (NP) expressed from the modified vaccinia virus Ankara (MVA) vaccine vector. These modifications resulted in increased antigen degradation, thereby producing elevated levels of peptides that can be presented on major histocompatibility complex (MHC) class I molecules to CD8+ T cells. Although we were unable to increase the NP-specific immune response in the mouse strain used, this approach may have benefits for vaccine development using less-immunogenic proteins.

Distribution of zoonotic variegated squirrel bornavirus 1 in naturally infected variegated and Prevost's squirrels.

Recently, the zoonotic capacity of the newly discovered variegated squirrel bornavirus 1 (VSBV-1) was confirmed in humans with a lethal encephalitis. Transmission to humans occurred by variegated and Prevost's squirrels as presumed reservoir hosts but possible ways of virus shedding and the route of infection still need to be elucidated. Thus, the tissue distribution of VSBV-1 antigen and RNA was investigated in detail via immunohistochemistry (IHC) in six variegated and eight Prevost's squirrels and by in situ hybridisation (ISH) in one Prevost's squirrel, respectively. VSBV-1 antigen and RNA positive cells were most numerous in the nervous system and were also found in nearly all tissues and different cell types indicating a broad organ and cell tropism of VSBV-1. Presence of VSBV-1 in several organs might indicate potential virus shedding via various routes and implies the risk of intra- and interspecies transmission, respectively.

Virus characterization and discovery in formalin-fixed paraffin-embedded tissues.

Detection and characterization of novel viruses is hampered frequently by the lack of properly stored materials. Especially for the retrospective identification of viruses responsible for past disease outbreaks, often only formalin-fixed paraffin-embedded (FFPE) tissue samples are available. Although FFPE tissues can be used to detect known viral sequences, the application of FFPE tissues for detection of novel viruses is currently unclear. In the present study it was shown that sequence-independent amplification in combination with next-generation sequencing can be used to detect sequences of known and unknown viruses, although with relatively low sensitivity. These findings indicate that this technique could be useful for detecting novel viral sequences in FFPE tissues collected from humans and animals with disease of unknown origin, when other samples are not available. In addition, application of this method to FFPE tissues allows to correlate with the presence of histopathological changes in the corresponding tissue sections.

Novel B19-like parvovirus in the brain of a harbor seal.

Using random PCR in combination with next-generation sequencing, a novel parvovirus was detected in the brain of a young harbor seal (Phoca vitulina) with chronic non-suppurative meningo-encephalitis that was rehabilitated at the Seal Rehabilitation and Research Centre (SRRC) in the Netherlands. In addition, two novel viruses belonging to the family Anelloviridae were detected in the lungs of this animal. Phylogenetic analysis of the coding sequence of the novel parvovirus, tentatively called Seal parvovirus, indicated that this virus belonged to the genus Erythrovirus, to which human parvovirus B19 also belongs. Although no other seals with similar signs were rehabilitated in SRRC in recent years, a prevalence study of tissues of seals from the same area collected in the period 2008-2012 indicated that the Seal parvovirus has circulated in the harbor seal population at least since 2008. The presence of the Seal parvovirus in the brain was confirmed by real-time PCR and in vitro replication. Using in situ hybridization, we showed for the first time that a parvovirus of the genus Erythrovirus was present in the Virchow-Robin space and in cerebral parenchyma adjacent to the meninges. These findings showed that a parvovirus of the genus Erythrovirus can be involved in central nervous system infection and inflammation, as has also been suspected but not proven for human parvovirus B19 infection.

Desmoplastic infantile astrocytoma and ganglioglioma: a search for genomic characteristics.

In the present study the clinical data, histology, proliferation rate, DNA ploidy status and the results of TP53 mutation analysis and comparative genomic hybridization (CGH) of three typical cases of desmoplastic infantile astrocytoma and ganglioglioma are presented. Postoperative disease-free intervals of 11, 8 and 3 years were recorded and in none of the cases were radiological signs of tumor recurrence. No TP53 mutations (exons 5-8) were found. CGH analysis revealed loss of 8p22-pter in one case, while in another case gain of 13q21 was detected. In the case with the follow-up of 11 years an aneuploid DNA-flow cytogram along with slightly increased MIB-1 labeling index (LI) was found. The results demonstrate little genetic instability in these low-grade lesions. DNA-aneuploidy seems not to be indicative of tumor progression. It is concluded that the genetic aberrations found in desmoplastic infantile ganglioglioma differ from those encountered in common astrocytomas.