Parapox infection in a gazelle kid (Gazella gazella)

Pseudocowpox virus infection in an American bison (Bison bison)

Background

The present report describes a case of pseudocowpox virus (PCPV) infection in a seven-year-old female bison euthanized due to a history of declining condition and sores on the vulva and udder.

Case presentation

External examination revealed multifocal, raised, keratinized plaques (0.5–2 cm) covering the skin of the ventral surface of the tail, perineum, caudoventral abdomen, udder, both inguinal recesses, and the medial aspects of both thighs. No significant gross lesions were present in the reminder of the tissues examined. Histopathological examination of the affected skin showed moderate epidermal hyperplasia with rete pegs, marked parakeratotic hyperkeratosis with crusts of degenerate neutrophils and cell debris, and few epithelial cells undergoing ballooning degeneration with occasional eosinophilic intracytoplasmic inclusion bodies (3–5 μm Bollinger body). Negative staining electron microscopy from skin revealed typical Parapoxvirus (PPV) particles, which were also confirmed by real-time PCR (Ct =18.6). Metagenomic analysis of the skin samples revealed only poxviruses. The bison parapox B2L envelope gene clustered with other parapox sequences identified from ruminants.

Conclusions

This is the first report of PCPV virus infection in an American bison. Identification of novel susceptible hosts of parapox viruses sheds light on the viral evolution and highlights the importance of potential economic impact of this disease to the bison industry.

Identification and phylogenetic analysis of an Orf virus isolated from an outbreak in sheep in the Jilin province of China

This study investigated an acute outbreak of contagious ecthyma dermatitis that occurred in November 2008 in a herd of 180 small-tailed Han sheep in the Jilin province of China. The pathological findings of this case revealed severe vascular proliferation, viral cytopathic changes in keratinocytes by vacuolar degeneration, ballooning degeneration, and eosinophilic cytoplasmic inclusions, suggesting that the disease could have been caused by an Orf virus (ORFV) infection. Immunohistochemistry, indirect immunofluorescence (IFA), and transmission electron microscopy supported the diagnosis of ORFV infection. Finally, the pathogen of the disease was identified using polymerase chain reaction (PCR) and sequences of major envelope protein genes (ORFV 011(B2L) and ORFV 059(F1L)). The full-length ORFV 011(B2L) and ORFV 059(F1L) genes were cloned and sequenced. The nucleotide and amino acid sequences of ORFV 011(B2L) and ORFV 059(F1L) genes in these outbreaks were analyzed, and their phylogenetic trees were constructed. The phylogenetic studies of ORFV 011(B2L) genes and ORFV 059(F1L) genes showed that the ORFV-Jilin province isolate clustered in different branches and was closer to the ORFV-Mukteswar 67/04 isolate and the ORFV-OV/C2 isolate, respectively. To date, there is no report on the molecular characterization of any Orf virus with other isolates around the world in mainland China. Further, the above results may provide some insight into the genotype of the etiological agent responsible for the contagious ecthyma dermatitis outbreak in the Jilin province, and could also provide a comparative view of the central coding region genomics of parapoxvirus (PPV).

Real-time PCR detection of parapoxvirus DNA

BACKGROUND

Detection of parapoxviruses is important in various animals as well as in humans as zoonotic infections. Reliable detection of parapoxviruses is fundamental for the exclusion of other rash-causing illnesses, for both veterinarians and medical practitioners. To date, however, no real-time PCR assay for the detection of parapoxviruses has been reported.

METHODS

A minor groove binder-based quantitative real-time PCR assay targeting the B2L gene of parapoxviruses was developed on the ABI Prism and the LightCycler platforms.

RESULTS

The real-time PCR assay successfully amplified DNA fragments from a total of 41 parapoxvirus strains and isolates representing the species orf virus, bovine papular stomatitis virus, pseudocowpoxvirus, and sealpoxvirus. Probit analysis gave a limit of detection of 4.7 copies per assay (95% confidence interval, 3.7-6.8 copies per reaction). Scabs contain a sufficient amount of parapoxvirus DNA and can therefore be used for PCR without any DNA preparation step. No cross-reactivity to human, bovine, or sheep genomic DNA or other DNA viruses, including orthopoxviruses, molluscum contagiosum viruses, and yaba-like disease viruses, was observed.

CONCLUSION

The presented assay is suitable for the detection of parapoxvirus infections in clinical material of human and animal origin.

Parapoxvirus infection in harbor seals (Phoca vitulina) from the German North Sea

In the summer of 2000, proliferative lesions of the skin and oral mucosa were observed in 26 young harbor seals (Phoca vitulina) from a rehabilitation center in Schleswig-Holstein, Germany. Verrucose, roundish nodules, approximately 1-2 cm in diameter, were presented in the oral cavity, especially on the tongue. Some animals developed similarly sized spherical dermal elevations with ulceration on flippers, chest, neck, and perineum. Necropsy of one animal showed multifocal, verrucose nodules in the oral cavity and a mild tonsillitis. Histologically, the nodules were characterized by ballooning degeneration of the outer parts of the spiny layer and stratum granulosum, with large eosinophilic cytoplasmic inclusions and a perivascular to interstitial lymphohistiocytic infiltration accompanied by fibroblastic proliferation and neovascularization. Negative staining of mucosal tissue homogenates demonstrated parapoxvirus-like particles. The presence of parapoxvirus was confirmed by polymerase chain reaction, using primers specific for parapoxvirus of ungulates. By in situ hybridization, using a parapox-specific, digoxigenin-labeled DNA probe, abundant parapoxvirus DNA-positive epithelial cells were detected in the stratum granulosum and the outer parts of the spiny layer. There was no parapoxvirus-positive signal in the adjacent submucosa. Although DNA analysis revealed that the causative agent can clearly be distinct from terrestrial parapoxviruses, lesions resembled parapoxvirus infections in other terrestrial species, and the pattern of virus DNA distribution indicated a direct effect of the virus on keratinocytes. In contrast, changes in the corium may be considered an indirect response mediated by the virus or the immune system.

Neuropathological study of gazelle herpesvirus 1 (equine herpesvirus 9) infection in Thomson's gazelles (Gazella thomsoni)

Gazelle herpesvirus (GHV-1), correctly designated as equine herpesvirus 9, is a new type of equine herpesvirus immunologically related to equine herpesvirus 1 (EHV-1). As a sequel to a virological study, the neuropathology of encephalitis caused by GHV-1 in Thomson's gazelles (Gazella thomsoni) was examined. Seven gazelles died with or without neurological symptoms between early September and mid-October in 1993. No gross abnormalities were observed at necropsy, but all animals had non-suppurative encephalitis, characterized by necrosis and degeneration of neurons, glial reactions and perivascular cuffing in the cerebrum. Five cases showed intranuclear inclusion bodies, with the appearance of herpesvirus in the degenerating neurons. Immunohistochemically, all seven animals showed a positive reaction to EHV-1 antigen in neurons in the necrotic areas of the cortex. The clinical course and morphological features of GHV-1 encephalitis were distinct from those of EHV-1-induced encephalitis in the horse, which is characterized by vasculitis, thrombosis, ischaemia, and lack of intranuclear inclusions in neurons.

Immune responses of the camel (Camelus dromedarius) to contagious ecthyma (Orf) virus infection

An enzyme-linked immunosorbent assay (ELISA) was developed together with a western blotting technique for the detection of total and specific IgG and IgM antibodies to the contagious ecthyma (orf) virus in camel (Camelus dromedarius) sera and for identifying the seroreactive antigens of the virus. An outbreak of generalised contagious ecthyma in camels was diagnosed for the first time in Libya; the seropositivity rate in a herd with clinically affected camels was 37.9% (and was related to clinical signs) and in apparently normal herds was 0% to 6.8%. Two viral antigenic determinants (22 and 40 kDa) were shared by the western blotting patterns of all the positive camel sera tested, another viral antigenic component of 28 kDa was shared by the positive sera with high ELISA titres. Very close similarity was seen with the western blot of orf-positive sheep sera. It is considered that the ELISA technique was valid for orf serodiagnosis in the camel and could be usefully applied to other species at risk of orf infection.