Reindeer Parapoxvirus

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Title: Reindeer Parapoxvirus
Author: Hautaniemi, Maria
Belongs to series: 3/2012
ISSN: 1796-4660 print
1797-2981 pdf
978-952-225-112-1 pdf
ISBN: 978-952-225-111-4 print
Abstract: Parapoxviruses (PPVs) are zoonotic viruses which cause contagious pustular skin infections of sheep, goats and cattle worldwide. In addition, they have more recently been shown to infect other animals such as red deer, seals, camels and reindeer. Cases of contagious pustular stomatitis in Finnish reindeer have been reported for many years. This economically important disease occurs typically during winter and is more common in the southern parts of the reindeer herding districts than in the north. The first severe outbreak occurred in the winter 1992-1993, and during the winter of 1999-2000 and in the late winter 2007 outbreaks of the disease were again observed. Usual symptoms include diminished appetite, drooling, fever, and later erosions and ulcerative lesions in the mouth. The aims of this study were to establish specific and rapid detection methods for the causative agent of the disease and characterize the viruses circulating in Finland. The causative agent of reindeer pustular stomatitis was originally considered to be Orf virus (ORFV) of the genus Parapoxvirus. PCR methods amplifying different regions of the PPV genomes were developed to analyse clinical samples obtained from outbreaks of the disease in reindeer and later from viruses isolated from the disease of sheep and cattle in Finland. Subsequent phylogenetic analyses of the Finnish PPVs, known members of the genus Parapoxvirus and selected members of the subfamily Chordopoxvirinae were conducted to identify the virus species isolated from reindeer. The results showed that the reindeer PPV from 1999-2000 is most closely related to the cattle PPV Pseudocowpox virus (PCPV) whereas the PPV strains from the winter of 1992-1993 outbreak grouped with sheep ORFV strains. Reindeer samples from the 2007 outbreak were identified as both PCPV and ORFV. Analysis of the similarity between genes of reindeer PCPV and ORFV isolates, Finnish sheep ORFV and cattle PCPV isolates indicated that these viruses have been circulating among Finnish reindeer, cattle and sheep at least ten years. Since the initial classification of the viruses causing pustular stomatitis in Finnish reindeer relied solely on the partial sequence analysis of virion core- and EEV envelope phospholipase protein sequences, the genome of PCPV-like reindeer isolate (F00.120R) was sequenced by shotgun sequencing of plasmid sublibraries of cosmids covering the central region of the genome, and by sequencing transposon random insertion libraries of plasmids derived from each end of the genome. The F00.120R and the genomic sequence of a reference strain of PCPV (VR634) were annotated and analyzed in this study. This first characterization of PCPV genomes revealed that F00.120R and VR634 are 135 and 145 kb in length and contain 131 and 134 putative genes, respectively. The organization of their genomes was found to be similar to that of other PPVs and both included 88 predicted genes that are conserved across all sequenced poxviruses. F00.120R was found to have four, possibly fragmented, genes at the left terminus and another near the central region of the genome that are not present in ORFV or Bovine papular stomatitis virus (BPSV; another PPV) genomes. In addition, the F00.120R genome was found to lack six genes seen near the right genome terminus of other PPVs. Comparing the PPV proteomes and whole genome phylogenetic analyses confirmed the classification of PCPV as a separate species within the PPV genus and verified that the virus causing pustular stomatitis in reindeer in 1999-2000 can be classified as PCPV. The observed six gene deletion at the right terminus of the F00.120R genome was further investigated in an attempt to use it in differentiating PCPV and ORFV causing pustular stomatitis in reindeer. The preliminary PCR analyses of wild type virus and early passages of F00.120R implied that the deletion of genes may have arisen during cell culture of the virus. The sequence around the deleted region was determined by sequencing two cloned overlapping PCR fragments from F00.120R wt virus isolated from lesion material. The same region was sequenced from an Italian PCPV field isolate (It1303). Further PCR analyses together with sequence determination showed that a 5431 bp sequence containing genes 116-121 was likely to have been deleted from the F00.120R genome prior to the 7th passage in cell culture. In addition, genes 116-121 were present in It1303 and in other isolates of reindeer and bovine PCPV isolated in Finland during the years 2005-2010. These results indicate that the genome of reindeer PCPV is about 140 kbp in length and has 137 genes instead of previously estimated length of 135 kbp and 131 genes; it contains homologues of all known ORFV genes and this analysis further reinforces the close genetic relationship between PCPV and ORFV.
Date: 2012

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