Invasion and maintenance of Dengue virus type 2 and type 4 in the Americas
Invasion and maintenance of Dengue virus type 2 and type 4 in the Americas
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DOI：
10.1128/jvi.79.23.14680-14687.2005
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发表时间：
2005-12-01
影响因子：
5.4
通讯作者：
Holmes, EC
中科院分区：
文献类型：
--
作者：
Carrington, CVF;Foster, JE;Holmes, EC
登革病毒4型（DENV-4）于1981年首次在美洲报道，在该地区引起登革热流行。同年，该地区报告了第一次登革出血热流行，由亚洲2型登革病毒株（DENV-2）引起，与以前流行的美洲亚型不同。尽管这些流行病很重要，但人们对病毒在岛屿和大陆人口中传播的速度或决定因素及其移动方向知之甚少。我们采用贝叶斯结合的方法来调查自1981年引入以来DENV-2和DENV-4的传播历史，并采用简约方法来评估应变迁移的模式。对于这两种病毒，存在初始入侵阶段，其特征在于DENV谱系数量的指数增加，之后尽管报道了DENV-2和DENV-4活性的波动，但遗传多样性水平保持恒定。值得注意的是，DENV-4的病毒谱系数量比DENV-2增加得快得多，表明DENV-4的指数种群增长率更快或地理扩散率更高，使该病毒能够更有效地在地区之间移动。我们认为，这些对比的动态可能反映了宿主免疫模式的根本差异。尽管继续基因流沿着特定的传播途径，病毒交通的整体程度低于预期的panmixis。因此，美洲的DENV具有明确的地理结构，在爆发之间保持病毒多样性。
Dengue virus type 4 (DENV-4) was first reported in the Americas in 1981, where it caused epidemics of dengue fever throughout the region. In the same year, the region's first epidemic of dengue hemorrhagic fever was reported, caused by an Asian strain of dengue virus type 2 (DENV-2) that was distinct from the American subtype circulating previously. Despite the importance of these epidemics, little is known about the rates or determinants of viral spread among island and mainland populations or their directions of movement. We employed a Bayesian coalescent approach to investigate the transmission histories of DENV-2 and DENV-4 since their introduction in 1981 and a parsimony method to assess patterns of strain migration. For both viruses there was an initial invasion phase characterized by an exponential increase in the number of DENV lineages, after which levels of genetic diversity remained constant despite reported fluctuations in DENV-2 and DENV-4 activity. Strikingly, viral lineage numbers increased far more rapidly for DENV-4 than DENV-2, indicative of a more rapid rate of exponential population growth in DENV-4 or a higher rate of geographic dispersal, allowing this virus to move more effectively among localities. We propose that these contrasting dynamics may reflect underlying differences in patterns of host immunity. Despite continued gene flow along particular transmission routes, the overall extent of viral traffic was less than expected under panmixis. Hence, DENV in the Americas has a clear geographic structure that maintains viral diversity between outbreaks.