J Gen Virol. 2015 Jun;96(Pt 6):1446-62.

Parapoxvirus (PPV) of red deer reveals subclinical infection and confirms a unique species.

 

Friederichs S1, Krebs S2, Blum H2, Lang H1, Büttner M3.
  • 1Bavarian Health and Food Safety Authority, Oberschleißheim, Germany.
  • 2Laboratory for Functional Genome Analysis (LAFUGA), Gene Centre, Ludwig-Maximilians-Universität München, Munich, Germany.
  • 3Bavarian Health and Food Safety Authority, Oberschleißheim, Germany Mathias.Buettner@lgl.bayern.de.

 

Abstract

Parapoxvirus (PPV) infections are of worldwide importance, particularly in sheep and goat herds. Owing to the zoonotic potential of all PPV species, they are a permanent threat to human health as well. The virus is also known to affect wildlife, as reported for pinnipeds, red deer and several other wild ruminants. PPVs found in red deer have been claimed as a unique species according to certain genomic features. So far infection of wildlife has been recognized because of clinical manifestation such as inflammation, stomatitis or typical pox-like lesions in the skin or mucous membranes. Here we report the use of targeted molecular diagnostics for the presence of PPV genomes in tonsil swabs of apparently healthy red deer in the Bavarian Alps. Out of 1764 swabs, 0.79 % tested positive for PPV genome presence. From one sample, PPV was successfully isolated in cell culture. This virus became the subject of complete genome characterization using next generation sequencing and various subsidiary PCR protocols. Strikingly, about a quarter of all ORFs were found to be larger than the corresponding ORFs in the reference PPV genome sequences used for comparison. To our knowledge this is the first genome-wide analysis that confirms red deer PPV as a unique species within the genus Parapoxvirus in Europe. Persistence of PPV in Alpine red deer indicates a source for virus transmission to susceptible livestock and hunters. The findings provide a further example of wildlife animals playing an important role as an inconspicuous reservoir of zoonotic diseases.

PMID: 25701822

 

Parapoxvirus (PPV) of red deer in Europe

Over the last three decades the incidence of emerging infectious diseases in humans has risen with about 70% of zoonotic etiology. Wildlife plays an important role as mostly asymptomatic sub-clinical reservoir hosts. Parapoxvirus (PPV) infections are of worldwide importance particularly in sheep and goat herds. Due to the zoonotic potential of all PPV species they are a permanent threat to human health as well. The virus is also known to affect wildlife as reported for pinnipeds, red deer and several other wild ruminants. With respect to poxvirus particle morphology PPV have an exceptional unique basket-like appearance with crisscross arrangement of core protein filaments in electron microscopy (Fig. 1). PPVs found in red deer have been claimed as a unique species according to certain genomic features. So far affection of wildlife has been recognized because of occasional clinical manifestation such as inflammation, stomatitis or typical pox-like lesions in the skin or mucous membranes. Molecular diagnostic screening for the presence of PPV genomes in tonsil swabs of apparently healthy red deer was performed in the Bavarian Alps. Tonsils are a first-line retention filter at the oral-nasal entry port and provide a perfect diagnostic matrix for pathogens not a priori causing a visible lesion. Out of 1764 swabs, 0.79% tested positive for PPV genome presence. From one sample PPV was successfully isolated in cell culture. In this study a genome-wide analysis confirms the existence of PPV in red deer as a unique species not only in New Zealand but also in Europe. Next generation sequencing (NGS) and various subsidiary PCR protocols revealed that about a quarter of all ORFs were found to be larger than the corresponding ORFs in the reference PPV genome sequences used for comparison. The genetic relationship among established PPV species is shown in Fig. 2 with PPV of red deer appearing on a separate branch in the genomic tree. To our knowledge the PPV isolate is the first red deer PPV from Europe. Persistence of PPV in Alpine red deer indicates a source for virus transmission to susceptible livestock and hunters. The findings provide a further example for wildlife animals playing an important role as an inconspicuous reservoir of zoonotic diseases.

 

PPVEM

Figure 1: Parapoxvirus particle: electron microscopy, negative staining uranyl acetate Regular crisscross arrangement of core filaments, particle size: ~ 260 nm long – 160 nm wide. Particle tightly surrounded by an envelope due to preparation partly detached from core.

 

 

PPVtree

Figure 2: Predicted protein sequences of PPV HL953 (acc. No.: KM502564) and protein sequence data of representatives of ORFV (IA82: AY38626¸SA00: AY386264.1, NZ2: DQ184476, B029: KF837136), BPSV (AR02: AY386265.1) and PCPV (F00.120R: GQ329669, VR634: GQ329670.1) were used to determine phylogenetic relationships within the PPV genus. The phylogenetic tree (maximum likelihood) was constructed based on concatenated data of those proteins present in all analyzed PPV genomes (∑ = 125 proteins). PPV HL 953, isolated from a red deer calf, is shown in bold. Analyses were performed with the MEGA 6.0 software (Tamura et al., 2013) using the Jones-Taylor-Thornton model for amino acid substitutions. The result was verified by bootstrap analysis of 100 replicates.

 

Tamura, K., Stecher, G., Peterson, D., Filipski, A. & Kumar, S. (2013). MEGA6: Molecular Evolutionary Genetics Analysis version 6.0. Mol Biol Evol 30, 2725–2729.

 

 

 

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