Suid alphaherpesvirus 1 of wild boar origin as a recent source of Aujeszky's disease in carnivores in Germany

BACKGROUND

The high susceptibility of carnivores to Suid Alphaherpesvirus 1 [SuAHV1, synonymous pseudorabies virus (PrV)], renders them inadvertent sentinels for the possible occurrence of Aujeszky's disease (AD) in domestic and wild swine populations. The aim of this study was to epidemiologically analyse the occurrence of PrV infections in domestic and wild animals in Germany during the last three decades and to genetically characterise the causative PrV isolates.

METHODS

PrV in dogs was detected using standard virological techniques including conventional and real time PCR, virus isolation or by immunohistochemistry. Available PrV isolates were characterized by partial sequencing of the open gC reading frame and the genetic traits were compared with those of archived PrV isolates from carnivores and domestic pigs from Germany before the elimination of AD in the domestic pig population.

RESULTS

During 1995 and 2022, a total of 38 cases of AD in carnivores, e.g. dogs and red foxes, were laboratory confirmed. Sequencing and subsequent phylogenetic analysis of PrV isolates established a strong connection between AD cases in carnivores and the occurrence of PrV infections in European wild boars in the end phase of and after elimination of AD from the domestic pig population. While PrV infections occur at low numbers but regularly in hunting dogs, interestingly, PrV was not observed in grey wolves in Germany. In none of 682 dead-found grey wolves and wolf-dog hybrids tested from Germany during 2006-2022 could PrV infection be detected by molecular means.

CONCLUSIONS

Although PrV has been eliminated from domestic pigs, spillover infections in domestic and wild carnivores should always be expected given the endemic presence of PrV in wild pig populations. Since detection of PrV DNA and virus in carnivores is sporadic even in areas with high seroprevalence of PrV in wild pigs, it may not reflect the full diversity of PrV.

Spatial Venomics─Cobra Venom System Reveals Spatial Differentiation of Snake Toxins by Mass Spectrometry Imaging

Among venomous animals, toxic secretions have evolved as biochemical weapons associated with various highly specialized delivery systems on many occasions. Despite extensive research, there is still limited knowledge of the functional biology of most animal toxins, including their venom production and storage, as well as the morphological structures within sophisticated venom producing tissues that might underpin venom modulation. Here, we report on the spatial exploration of a snake venom gland system by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), in combination with standard proteotranscriptomic approaches, to enable in situ toxin mapping in spatial intensity maps across a venom gland sourced from the Egyptian cobra (Naja haje). MALDI-MSI toxin visualization on the elapid venom gland reveals a high spatial heterogeneity of different toxin classes at the proteoform level, which may be the result of physiological constraints on venom production and/or storage that reflects the potential for venom modulation under diverse stimuli.

In action-an early warning system for the detection of unexpected or novel pathogens

Proactive approaches in preventing future epidemics include pathogen discovery prior to their emergence in human and/or animal populations. Playing an important role in pathogen discovery, high-throughput sequencing (HTS) enables the characterization of microbial and viral genetic diversity within a given sample. In particular, metagenomic HTS allows the unbiased taxonomic profiling of sequences; hence, it can identify novel and highly divergent pathogens such as viruses. Newly discovered viral sequences must be further investigated using genomic characterization, molecular and serological screening, and/or invitro and invivo characterization. Several outbreak and surveillance studies apply unbiased generic HTS to characterize the whole genome sequences of suspected pathogens. In contrast, this study aimed to screen for novel and unexpected pathogens in previously generated HTS datasets and use this information as a starting point for the establishment of an early warning system (EWS). As a proof of concept, the EWS was applied to HTS datasets and archived samples from the 2018–9 West Nile virus (WNV) epidemic in Germany. A metagenomics read classifier detected sequences related to genome sequences of various members of Riboviria. We focused the further EWS investigation on viruses belonging to the families Peribunyaviridae and Reoviridae, under suspicion of causing co-infections in WNV-infected birds. Phylogenetic analyses revealed that the reovirus genome sequences clustered with sequences assigned to the species Umatilla virus (UMAV), whereas a new peribunyavirid, tentatively named ‘Hedwig virus’ (HEDV), belonged to a putative novel genus of the family Peribunyaviridae. In follow-up studies, newly developed molecular diagnostic assays detected fourteen UMAV-positive wild birds from different German cities and eight HEDV-positive captive birds from two zoological gardens. UMAV was successfully cultivated in mosquito C6/36 cells inoculated with a blackbird liver. In conclusion, this study demonstrates the power of the applied EWS for the discovery and characterization of unexpected viruses in repurposed sequence datasets, followed by virus screening and cultivation using archived sample material. The EWS enhances the strategies for pathogen recognition before causing sporadic cases and massive outbreaks and proves to be a reliable tool for modern outbreak preparedness.

Re-Emergence and Spread of Haemorrhagic Septicaemia in Germany: The Wolf as a Vector?

Since 2010, outbreaks of haemorrhagic septicaemia (HS) caused by Pasteurella (P.) multocida capsular type B (PmB) emerged in Germany. In 2017, we noticed a close spatiotemporal relationship between HS outbreak sites and wolf (Canis lupus) territories. Thus, the main objectives of our study were to investigate the molecular epidemiology of German PmB-HS-isolates and to assess the role of wolves as putative vectors of this pathogen. We collected 83 PmB isolates from HS outbreaks that occurred between 2010 and 2019 and sampled 150 wolves, which were found dead in the years 2017 to 2019, revealing another three PmB isolates. A maximum-likelihood-based phylogeny of the core genomes of 65 PmB-HS-isolates and the three PmB-wolf-isolates showed high relatedness. Furthermore, all belonged to capsular:LPS:MLST genotype B:L2:ST122^RIRDC and showed highly similar virulence gene profiles, but clustered separately from 35 global ST122^RIRDC strains. Our data revealed that German HS outbreaks were caused by a distinct genomic lineage of PmB-ST122 strains, hinting towards an independent, ongoing epidemiologic event. We demonstrated for the first time, that carnivores, i.e., wolves, might harbour PmB as a part of their oropharyngeal microbiota. Furthermore, the results of our study imply that wolves can carry the pathogen over long distances, indicating a major role of that animal species in the ongoing epidemiological event of HS in Germany.

Replication of Rift Valley Fever Virus in Amphibian and Reptile-Derived Cell Lines

Rift Valley fever phlebovirus (RVFV) is a zoonotic arthropod-borne virus, which has led to devastating epidemics in African countries and on the Arabian Peninsula. Results of in-vivo, in-vitro and field studies suggested that amphibians and reptiles may play a role as reservoir hosts of RVFV, promoting its maintenance during inter-epidemic periods. To elucidate this hypothesis, we examined two newly established reptile-derived cell lines (Egyptian cobra and Chinese pond turtle) and five previously generated reptile- and amphibian-derived cell lines for their replicative capacity for three low- and high-pathogenic RVFV strains. At different time points after infection, viral loads (TCID₅₀), genome loads and the presence of intracellular viral antigen (immunofluorescence) were assessed. Additionally, the influence of temperatures on the replication was examined. Except for one cell line (read-eared slider), all seven cell lines were infected by all three RVFV strains. Two different terrapin-derived cell lines (Common box turtle, Chinese pond turtle) were highly susceptible. A temperature-dependent replication of RVFV was detected for both amphibian and reptile cells. In conclusion, the results of this study indicate the general permissiveness of amphibian and reptile cell lines to RVFV and propose a potential involvement of terrapins in the virus ecology.

Co-infections: Simultaneous detections of West Nile virus and Usutu virus in birds from Germany

The emergence of West Nile virus (WNV) and Usutu virus (USUV) in Europe resulted in significant outbreaks leading to avifauna mortality and human infections. Both viruses have overlapping geographical, host and vector ranges, and are often co-circulating in Europe. In Germany, a nationwide bird surveillance network was established to monitor these zoonotic arthropod-borne viruses in migratory and resident birds. In this framework, co-infections with WNV and USUV were detected in six dead birds collected in 2018 and 2019. Genomic sequencing and phylogenetic analyses classified the detected WNV strains as lineage 2 and the USUV strains as lineages Africa 2 (n = 2), Africa 3 (n = 3) and Europe 2 (n = 1). Preliminary attempts to co-propagate both viruses in vitro failed. However, we successfully cultivated WNV from two animals. Further evidence for WNV-USUV co-infection was obtained by sampling live birds in four zoological gardens with confirmed WNV cases. Three snowy owls had high neutralizing antibody titres against both WNV and USUV, of which two were also positive for USUV-RNA. In conclusion, further reports of co-infections in animals as well as in humans are expected in the future, particularly in areas where both viruses are present in the vector population.

Streptococcus catagoni sp. nov., isolated from the respiratory tract of diseased Chacoan peccaries (Catagonus wagneri)

Novel catalase-negative, Gram-stain-positive, beta-haemolytic, coccus-shaped organisms were isolated from Chacoan peccaries that died from respiratory disease. The initial API 20 Strep profiles suggested Streptococcus agalactiae with acceptable identification scores, but the 16S rRNA gene similarity (1548 bp) to available sequences of streptococci was below 98 %. Next taxa of the genus Streptococcus, displaying highest similarities to the strains from this study, were S. bovimastitidis NZ1587^T (97.5 %), S. iniae ATCC 29178^T (97.5 %), S. hongkongensis HKU30^T (97.4 %), S. parauberis DSM 6631^T (97.1 %), S. penaeicida CAIM 1838^T (97.1 %), S. pseudoporcinus DSM 18513^T (97.0 %), S. didelphis DSM 15616^T (96.6 %), S. ictaluri 707-05^T (96.6 %), S. uberis JCM 5709^T (96.5 %) and S. porcinus NCTC 10999^T (96.4 %). All other Streptococcus species had sequence similarities of below 96.4 %. A sodA gene as well as whole genome-based core genome phylogeny of three representative strains and 145 available Streptococcus genomes confirmed the unique taxonomic position. Interstrain average nucleotide identity (ANI) and amino acid identity (AAI) values were high (ANI >96 %; AAI 100%), but for other streptococci clearly below the proposed species boundary of 95-96 % (ANI <75 %; AAI <83 %). Results were confirmed by genome-to-genome distance calculations. Pairwise digital DNA-DNA hybridization estimates were high (>90 %) between the novel strains, but well below the species boundary of 70 % for closely related Streptococcus type strains (23.5-19.7 %). Phenotypic properties as obtained from extended biochemical profiles and MALDI-TOF mass spectrometry supported the outstanding rank. Based on the presented molecular and physiological data of the six strains, we propose a novel taxon for which we suggest the name Streptococcus catagoni sp. nov. with the type strain 99-1/2017^T (=DSM 110457^T=CCUG 74072^T) and five reference strains.

Molecular survey of tick-borne pathogens reveals a high prevalence and low genetic variability of Hepatozoon canis in free-ranging grey wolves (Canis lupus) in Germany

Wild carnivores are important hosts for ixodid ticks and presumed reservoirs for several tick-borne pathogens (TBPs) of medical and veterinary importance. However, little is known about the role that the European grey wolf (Canis lupus) plays in the enzootic cycle of TBPs. The recent recolonization of Central European lowland, including some regions in Germany, by the grey wolf, opened up an excellent opportunity for studying the impact of the wolf population on pathogen diversity and transmission dynamics. Therefore, in the present study, we investigated spleen samples collected from 276 grey wolves in 11 federal states in Germany for common TBPs by molecular methods. In total, 127 grey wolves (46.0 %) were found to be positive for Hepatozoon canis. Only two genetic variants of this protozoan parasite (herein designated as G1 and G2) were found to circulate among the grey wolves, which can be potentially shared between populations of domestic and other wild carnivores in the country. Two grey wolves were positive for Anaplasma phagocytophilum (0.7 %), and both were co-infected with H. canis G1 genotype. The presence of other pathogens could not be confirmed by PCR and sequencing. This study represents the first one reporting H. canis in a grey wolf population worldwide, and it provides highly relevant information, which may contribute to a better understanding of the epidemiology of TBPs and the pathogen transmission dynamics among the reintroduced population of grey wolves and other carnivores.

Comparing erosion and organ accumulation rates of lead and alternative lead-free ammunition fed to captive domestic ducks

Lead poisoning of birds of prey from ingestion of ammunition lead has been well documented. Alternative, lead-free ammunition is widely available, but the toxicokinetics of other metals in birds are poorly understood. We tested the erosion of lead, copper, zinc, iron and brass by feeding domestic Pekin ducks (Anas platyrhynchos forma domestica) defined numbers of small metal pellets. The accumulation of these metals was analysed in the breast muscle, brain, pancreas, liver and kidney. Four weeks after application, the ducks were euthanized and necropsied, internal organs tested for metal accumulation and gizzard pellets collected and weighed to record loss by erosion. Degree of erosion was highest in zinc pellets (81% mass loss), followed by iron (46%) and lead (45%) and was only marginal in copper and brass. Only lead showed highly elevated levels of accumulation in organs compared to controls.

Tox-positive Corynebacterium ulcerans in hedgehogs, Germany. Emerg Microbes Infect 2019;8:211-217. [PMID: 30866774 PMCID: PMC6455118 DOI: 10.1080/22221751.2018.1562312]

Toxigenic Corynebacterium ulcerans may cause both respiratory and cutaneous diphtheria in humans. As a zoonotic emerging pathogen it has been isolated from a wide variety of animals living in captivity, such as livestock, pet, zoo and research animals and additionally in a large number of different wild animals. Here we report the isolation of tox-positive C. ulcerans in four hedgehogs with cutaneous diphtheria and pneumonia, respectively.

Population expansion and individual age affect endoparasite richness and diversity in a recolonising large carnivore population

The recent recolonisation of the Central European lowland (CEL) by the grey wolf (Canis lupus) provides an excellent opportunity to study the effect of founder events on endoparasite diversity. Which role do prey and predator populations play in the re-establishment of endoparasite life cycles? Which intrinsic and extrinsic factors control individual endoparasite diversity in an expanding host population? In 53 individually known CEL wolves sampled in Germany, we revealed a community of four cestode, eight nematode, one trematode and 12 potential Sarcocystis species through molecular genetic techniques. Infections with zoonotic Echinococcus multilocularis, Trichinella britovi and T. spiralis occurred as single cases. Per capita endoparasite species richness and diversity significantly increased with population size and changed with age, whereas sex, microsatellite heterozygosity, and geographic origin had no effect. Tapeworm abundance (Taenia spp.) was significantly higher in immigrants than natives. Metacestode prevalence was slightly higher in ungulates from wolf territories than from control areas elsewhere. Even though alternative canid definitive hosts might also play a role within the investigated parasite life cycles, our findings indicate that (1) immigrated wolves increase parasite diversity in German packs, and (2) prevalence of wolf-associated parasites had declined during wolf absence and has now risen during recolonisation.

The role of 'atypical' Brucella in amphibians: are we facing novel emerging pathogens?

AIMS

To discuss together the novel cases of Brucella infections in frogs with the results of published reports to extend our current knowledge on 'atypical' brucellae isolated from amphibians and to discuss the challenges we face on this extraordinary emerging group of pathogens.

METHODS AND RESULTS

Since our first description, an additional 14 isolates from four different frog species were collected. Novel isolates and a subset of Brucella isolates previously cultured from African bullfrogs were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), Fourier transform-infrared (FT-IR) spectroscopy and broth microdilution susceptibility testing. MALDI-TOF MS worked very efficiently for an accurate bacterial identification to the genus level. Within the cluster analysis, 'atypical' brucellae grouped distant from Brucella melitensis and were even more separated by FT-IR spectroscopy with respect to their geographical origin. Minimum inhibitory concentrations of 14 antimicrobial substances are provided as baseline data on antimicrobial susceptibility.

CONCLUSIONS

The case history of Brucella infections in amphibians reveals a variety of pathologies ranging from localized manifestations to systemic infections. Some isolates seem to be capable of causing high mortality in zoological exhibitions putting higher demands on the management of endangered frog species. There is considerable risk in overlooking and misidentifying 'atypical' Brucella in routine diagnostics.

SIGNIFICANCE AND IMPACT OF THE STUDY

Brucella have only recently been described in cold-blooded vertebrates. Their presence in frog species native to Africa, America and Australia indicates a more common occurrence in amphibians than previously thought. This study provides an extensive overview of amphibian brucellae by highlighting the main features of their clinical significance, diagnosis and zoonotic potential.

Zebra Alphaherpesviruses (EHV-1 and EHV-9): Genetic Diversity, Latency and Co-Infections

Alphaherpesviruses are highly prevalent in equine populations and co-infections with more than one of these viruses’ strains frequently diagnosed. Lytic replication and latency with subsequent reactivation, along with new episodes of disease, can be influenced by genetic diversity generated by spontaneous mutation and recombination. Latency enhances virus survival by providing an epidemiological strategy for long-term maintenance of divergent strains in animal populations. The alphaherpesviruses equine herpesvirus 1 (EHV-1) and 9 (EHV-9) have recently been shown to cross species barriers, including a recombinant EHV-1 observed in fatal infections of a polar bear and Asian rhinoceros. Little is known about the latency and genetic diversity of EHV-1 and EHV-9, especially among zoo and wild equids. Here, we report evidence of limited genetic diversity in EHV-9 in zebras, whereas there is substantial genetic variability in EHV-1. We demonstrate that zebras can be lytically and latently infected with both viruses concurrently. Such a co-occurrence of infection in zebras suggests that even relatively slow-evolving viruses such as equine herpesviruses have the potential to diversify rapidly by recombination. This has potential consequences for the diagnosis of these viruses and their management in wild and captive equid populations.

Anti-NMDA Receptor Encephalitis in the Polar Bear (Ursus maritimus) Knut

Knut the polar bear of the Berlin Zoological Garden drowned in 2011 following seizures and was diagnosed as having suffered encephalitis of unknown etiology after exhaustive pathogen screening. Using the diagnostic criteria applied to human patients, we demonstrate that Knut’s encephalitis is almost identical to anti-NMDA receptor encephalitis which is a severe autoimmune disease representing the most common non-infectious encephalitis in humans. High concentrations of antibodies specific against the NR1 subunit of the NMDA receptor were detected in Knut’s cerebrospinal fluid. Histological examination demonstrated very similar patterns of plasma cell infiltration and minimal neuronal loss in affected brain areas. We conclude that Knut suffered anti-NMDA receptor encephalitis making his the first reported non-human case of this treatable disease. The results suggest that anti-NMDA receptor encephalitis may be a disease of broad relevance to mammals that until now has remained undiagnosed.

A potentially fatal mix of herpes in zoos

Pathogens often have a limited host range, but some can opportunistically jump to new species. Anthropogenic activities that mix reservoir species with novel, hence susceptible, species can provide opportunities for pathogens to spread beyond their normal host range. Furthermore, rapid evolution can produce new pathogens by mechanisms such as genetic recombination. Zoos unintentionally provide pathogens with a high diversity of species from different continents and habitats assembled within a confined space. Institutions alert to the problem of pathogen spread to unexpected hosts can monitor the emergence of pathogens and take preventative measures. However, asymptomatic infections can result in the causative pathogens remaining undetected in their reservoir host. Furthermore, pathogen spread to unexpected hosts may remain undiagnosed if the outcome of infection is limited, as in the case of compromised fertility, or if more severe outcomes are restricted to less charismatic species that prompt only limited investigation. We illustrate this problem here with a recombinant zebra herpesvirus infecting charismatic species including zoo polar bears over at least four years. The virus may cause fatal encephalitis and infects at least five mammalian orders, apparently without requiring direct contact with infected animals.

Dystocia and fetotomy associated with cerebral aplasia in a greater one-horned rhinoceros (Rhinoceros unicornis)

The captive greater one-horned rhinoceros population consists of 176 animals. Since 1971, a total of 226 calves were born into this captive population. However, 24% of the offspring born were either stillborn or did not survive the first 3 months. The causes for this high rate of stillbirth and neonate mortality have not yet been documented. Here, we report on the veterinary management of a dystocia and foetotomy resulting from a malpositioned greater one-horned rhinoceros foetus. The dead foetus presented with a forelimb flexed at the shoulder joint, with all other joints extended. The foetus was dissected into five parts and extracted during two anaesthesias on two consecutive days. The dam recovered fully and came into oestrous 31 days after surgery. Post-mortem and CT examination of the malformed foetal head revealed cranioschisis with cerebral aplasia and cerebellar hypoplasia. The cerebral aplasia presented here and in other recent cases suggests that neural tube defects and cranial malformations may be associated with more captive rhinoceros stillbirths than previously considered. Epidemiologic studies of these phenomena and possible nutritional deficiencies or hereditary defects are warranted.

Polycystic kidney disease in adult Brazilian agoutis (Dasyprocta leporina)

During the last 21 years, 7 adult captive Brazilian agoutis (Dasyprocta leporina) from 4 different zoologic gardens were necropsied and histologically examined at the Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany. All animals had polycystic kidney disease as the major pathologic change. Except in 1 case, no clinical signs were recognized prior to death. The animals had macroscopic bilateral alterations of the kidneys ranging from granulated surfaces to severe polycystic changes. Microscopic examination revealed multifocal to generalized, moderate to severe cystic dilatations of Bowman's capsules and renal tubules, moderate mesangial and capsular proliferation of the renal corpuscles, mild interstitial fibrosis, and mild to moderate interstitial lympho-plasmacytic infiltrations. Little information is known about the genetic relationships of these animals, but breeding practice indicates a high possibility of inbred agouti zoo populations in Germany. This is the first report on polycystic kidney disease in Brazilian agoutis with possible genetic background.

Lethal pneumonia in a captive juvenile chimpanzee (Pan troglodytes) due to human-transmitted human respiratory syncytial virus (HRSV) and infection with Streptococcus pneumoniae

BACKGROUND

During an outbreak of respiratory disease in captive chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), Bornean orangutans (Pongo pygmaeus), and red-capped mangabeys (Cercocebus torquatus) also staff members showed non-specific upper respiratory signs. One infant female chimpanzee with severe respiratory symptoms died despite immediate medical treatment and was submitted for necropsy.

METHODS

Routine post mortem, histological and bacteriological examinations were conducted. Additionally lung tissue samples form the chimpanzee and swab samples from the staff members and the other primates were examined by PCR.

RESULTS

A severe catarrhal to purulent bronchopneumonia and an interstitial pneumonia were found and human respiratory syncytial virus (HRSV) as well as Streptococcus pneumoniae was detected in lung samples by PCR. Swab samples from one animal keeper revealed the same HRSV sequence as of the chimpanzee.

CONCLUSIONS

Therefore, it is suggested that the outbreak of respiratory disease within a zoological institution was due to transmission of HRSV between both human and primates.