Himsworth Chelsea G, Musil Kristyna M, Bryan Lorraine, Hill Janet E
Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
J Wildl Dis. 2009 Oct;45(4):1143-9. doi: 10.7589/0090-3558-45.4.1143.
There are two recognized poxviruses that are associated with disease in tree squirrels: squirrel fibroma virus (SQFV), Leporipoxvirus, which affects eastern grey squirrels (Sciurus carolinensis) in eastern North America, and squirrelpox virus (SQPV), a member of a newly identified poxvirus genus, which affects European red squirrels (Sciurus vulgaris) in the United Kingdom. In August 2008, a cutaneous poxvirus-associated disease was identified in a North American red squirrel (Tamiasciurus hudsonicus) from the Yukon Territory, Canada. The gross and microscopic appearance of the skin lesions was more consistent with SQPV than SQFV, and electron microscopy revealed poxvirions only within epithelial cells. Polymerase chain reaction (PCR) was used to identify poxvirus core protein encoding DNA in skin samples, and phylogenetic analysis showed that the inferred amino acid sequence was distinct from all other poxvirus species for which the core protein gene has been sequenced, including those of the genus Leporipoxvirus. Although the core protein sequence of SQPV was not available, comparison of the constructed phylogenetic tree to other published trees, based on major outer envelope proteins, revealed that the identified sequence occupies a position similar to SQPV in terms of its relationship to other poxviruses. However, PCR primers designed to amplify gene sequences encoding the SQPV major envelope protein and RNA polymerase did not amplify any sequences from infected tissues. These findings suggest that the virus present in this squirrel is a novel poxvirus of North American red squirrels. To our knowledge, this is the first case of poxvirus infection in Canadian squirrels outside of Ontario.
松鼠纤维瘤病毒（SQFV），属于兔痘病毒属，影响北美洲东部的东部灰松鼠（Sciurus carolinensis）；以及松鼠痘病毒（SQPV），是新鉴定的痘病毒属的成员，影响英国的欧洲红松鼠（Sciurus vulgaris）。2008年8月，在加拿大育空地区的一只北美红松鼠（Tamiasciurus hudsonicus）身上发现了一种与皮肤痘病毒相关的疾病。皮肤病变的大体和显微镜下表现与SQPV比SQFV更为一致，电子显微镜检查仅在上皮细胞内发现痘病毒粒子。聚合酶链反应（PCR）用于鉴定皮肤样本中编码痘病毒核心蛋白的DNA，系统发育分析表明，推断的氨基酸序列与所有其他已对核心蛋白基因进行测序的痘病毒物种不同，包括兔痘病毒属的那些物种。尽管没有SQPV的核心蛋白序列，但将构建的系统发育树与基于主要外膜蛋白的其他已发表树进行比较，发现所鉴定的序列在与其他痘病毒的关系方面占据与SQPV相似的位置。然而，设计用于扩增编码SQPV主要包膜蛋白和RNA聚合酶的基因序列的PCR引物未能从受感染组织中扩增出任何序列。这些发现表明，这只松鼠身上存在的病毒是北美红松鼠的一种新型痘病毒。据我们所知，这是安大略省以外加拿大松鼠中首例痘病毒感染病例。
