Research Seminar 19.5.2009: Parapoxviruses in reindeer mouth disease


<div>For several years and particularly in winter, a contagious pustular dermatitis (also known as reindeer mouth disease) has been known to occur among Finnish reindeer. The disease spreads easily in epidemic regions and causes considerably economic losses to reindeer husbandry.</div>

Researcher Maria Hautaniemi
Veterinary Virology Research Unit, Evira, Helsinki
Evira/Helsinki Viikki, Auditorium C111 Kalevi
Tue 10.3.2009, 3:00–4:00 pm

Symptoms of the disease include reduced appetite, fever, erosions and proliferative lesions in the lips and oral mucosa of the infected animals.

Reindeer mouth disease epidemics

The most severe epidemic to date occurred in winter 1992-1993 when about 400 reindeer died and almost 3000 required veterinary care. At the same time symptoms of the disease were found amongst humans having handled sick reindeer, as well as in some sheep. At that time, the presence of parapoxvirus (PPV) in reindeer and human samples was demonstrated by electron microscopic studies.

Parapoxviruses belong to the family Poxviridae, which includes more than 80 large DNA viruses infecting both animals and insects. There are currently four established PPV species in the genus: Orf virus (ORFV), which is maintained mainly in sheep and goats, Bovine papular stomatitis virus (BPSV) and Pseudocowpox virus (PCPV), which are maintained mainly in cattle, and Parapoxvirus of red deer in New Zealand (PVNZ), which so far has only been found in New Zealand.

Since the winter 1992-1993 outbreak the disease has occurred to a varying extent throughout the reindeer herding area until a second small epidemic in the winter 1999-2000. Our previous studies have shown that these two outbreaks were caused by different species of PPVs; the outbreak during the winter 1992-1993 was caused by an ORFV like virus and the latter outbreak in the winter 1999-2000 was caused by a virus closely related to bovine PCPV.

Evira started a project for sequencing the genome of parapoxvirus

PCPV has previously been demonstrated to cause infection only in cattle and humans but all other species tested, including sheep, have been shown to be resistant to the virus. The previous studies showed that the cause of the disease in winter 1999–2000 was a virus related to PCPV, but because the precise origin of the virus could not be defined, Evira started a project for sequencing the entire genome of the ”new” parapoxvirus of reindeer that has dominated the 2000s. This work has been done in collaboration with Moredun Research Institute (Edinburgh, UK), High Throughput Center/ Biomedicum and Molecular Medicine Sequencing Laboratory/ Biomedicum, and the Virus Research Unit at the University of Otago (New Zealand), where the first PCPV genome has been simultaneously sequenced.

The genome of reindeer parapoxvirus has been shown to be structurally similar to other sequenced poxviruses, although there are significant differences compared to closely related ORF and BPS viruses, e.g. reindeer parapoxvirus is lacking six genes at the right-hand end of the genome. The reindeer virus has most of the virulence and immunomodulatory genes found in other parapoxviruses, but in addition, new putative genes unknown in other viruses are present in reindeer PPV. Comparative study of PPV genomes has shown that the reindeer virus is originally transmitted from cattle to reindeer.

Additional information:
Researcher Maria Hautaniemi, Veterinary Virology Research Unit, maria.hautaniemi,
tel. 050 573 6891

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