Division of Biology, Kansas State University, 116 Ackert Hall, Manhattan, KS 66506, USA.
Mol Ecol. 2010 Jul;19(13):2725-38. doi: 10.1111/j.1365-294X.2010.04668.x. Epub 2010 Jun 5.
Viral strain evolution and disease emergence are influenced by anthropogenic change to the environment. We investigated viral characteristics, host ecology, and landscape features in the rabies-striped skunk disease system of the central Great Plains to determine how these factors interact to influence disease emergence. We amplified portions of the N and G genes of rabies viral RNA from 269 samples extracted from striped skunk brains throughout the distribution of two different rabies strains for which striped skunks were the reservoir. Because the distribution of these two strains overlapped on the landscape and were present in the same host population, we could evaluate how viral properties influenced epidemiological patterns in the area of sympatry. We found that South Central Skunk rabies (SCSK) exhibited intense purifying selection and high infectivity, which are both characteristics of an epizootic virus. Conversely, North Central Skunk rabies (NCSK) exhibited relaxed purifying selection and comparatively lower infectivity, suggesting the presence of an enzootic virus. The host population in the area of sympatry was highly admixed, and skunks among allopatric and sympatric areas had similar effective population sizes. Spatial analysis indicated that landscape features had minimal influence on NCSK movement across the landscape, but those same features were partial barriers to the spread of SCSK. We conclude that NCSK and SCSK have different epidemiological properties that interact differently with both host and landscape features to influence rabies spread in the central Great Plains. We suggest a holistic approach for future studies of emerging infectious diseases that includes studies of viral properties, host characteristics, and spatial features.
病毒株的进化和疾病的出现受到人类对环境改变的影响。我们调查了狂犬病条纹臭鼬疾病系统中的病毒特征、宿主生态学和景观特征，以确定这些因素如何相互作用影响疾病的出现。我们从分布在两种不同狂犬病毒株的条纹臭鼬大脑中提取的 269 个样本中扩增了狂犬病病毒 RNA 的 N 和 G 基因部分，这两种毒株的条纹臭鼬都是其宿主。由于这两种菌株在景观上重叠，并且存在于同一宿主种群中，我们可以评估病毒特性如何影响同域地区的流行病学模式。我们发现，中南部臭鼬狂犬病（SCSK）表现出强烈的纯化选择和高感染力，这都是爆发性病毒的特征。相反，中北部臭鼬狂犬病（NCSK）表现出放松的纯化选择和相对较低的感染力，表明存在地方性病毒。同域地区的宿主种群高度混合，而在同域和异域地区的臭鼬具有相似的有效种群大小。空间分析表明，景观特征对 NCSK 在景观中的传播影响最小，但这些相同的特征是 SCSK 传播的部分障碍。我们得出结论，NCSK 和 SCSK 具有不同的流行病学特性，它们与宿主和景观特征的相互作用不同，从而影响大平原中部的狂犬病传播。我们建议对新兴传染病的未来研究采取整体方法，包括病毒特性、宿主特征和空间特征的研究。
