Root J Jeffrey, Oesterle Paul T, Nemeth Nicole M, Klenk Kaci, Gould Daniel H, McLean Robert G, Clark Larry, Hall Jeffrey S
United States Department of Agriculture, Wildlife Services, National Wildlife Research Center, Fort Collins, CO 80521, USA.
Am J Trop Med Hyg. 2006 Oct;75(4):697-701.
Tree squirrels (Sciurus spp.) have exhibited high seroprevalence rates, suggesting that they are commonly exposed to West Nile virus (WNV). Many characteristics of WNV infections in tree squirrels, such as the durations and levels of viremia, remain unknown. To better understand WNV infections in fox squirrels (S. niger), we subcutaneously inoculated fourteen fox squirrels with WNV. Peak viremias ranged from 10(4.00) plaque-forming units (PFU)/mL of serum on day 2 post-infection (DPI) to 10(4.98) PFU/mL on 3 DPI, although viremias varied between individuals. Oral secretions of some fox squirrels were positive for WNV viral RNA, occasionally to moderate levels (10(3.2) PFU equivalent/swab). WNV PFU equivalents in organs were low or undetectable on 12 DPI; gross and histologic lesions were rare. The viremia profiles of fox squirrels indicate that they could serve as amplifying hosts in nature. In addition, viral RNA in the oral cavity and feces indicate that this species could contribute to alternative WNV transmission in suburban communities.
松鼠（松鼠属）呈现出较高的血清阳性率，这表明它们普遍接触西尼罗河病毒（WNV）。松鼠感染WNV的许多特征，如病毒血症的持续时间和水平，仍然未知。为了更好地了解狐松鼠（S. niger）感染WNV的情况，我们给14只狐松鼠皮下接种了WNV。病毒血症峰值范围从感染后第2天（DPI）的10(4.00) 空斑形成单位（PFU）/mL血清到第3天的10(4.98) PFU/mL，尽管不同个体的病毒血症有所不同。一些狐松鼠的口腔分泌物中WNV病毒RNA呈阳性，偶尔达到中等水平（10(3.2) PFU当量/拭子）。在12 DPI时，器官中的WNV PFU当量很低或无法检测到；肉眼和组织学病变很少见。狐松鼠的病毒血症特征表明它们在自然环境中可能充当扩增宿主。此外，口腔和粪便中的病毒RNA表明该物种可能在郊区社区中促成WNV的其他传播途径。
