人間の海洋移動にともなう分散がフィリピン列島における媒介蚊ネッタイシマ蚊の集団遺伝構造に影響

長崎大学学位論文 [学位記番号]博（医歯薬）甲第794号 [学位授与年月日]平成27年9月18

Susceptibility of Indigenous and Transplanted Mosquito Spp. to Dengue Virus in Japan

Dengue fever, an acute, mosquito-borne, febrile illness caused by Flavivirus spp., is a problem in Africa, South and Southeast Asia, Latin America, and the Caribbean. A dengue outbreak occurred after nearly 70 years of absence or no detection, and then 158 autochthonous cases occurred in Japan from August to October 15, 2014. The most competent mosquito vectors for dengue virus transmission were Aedes aegypti and A. albopictus. Since A. albopictus is widely distributed across Japan and A. aegypti recently invaded Japan by airplane, we examined the susceptibility of these species to infection by dengue virus

STRUCTURE bar plots.

<p>Each individual is represented by a vertical bar whose colors show the probability to be assigned to specific clusters. Populations are separated by vertical black lines and identified by the numbers at the bottom (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.g001" target="_blank">Fig 1</a> and <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.t001" target="_blank">Table 1</a>). K = number of genetic clusters. Overall, a low level of genetic structure was detected. At K6 and K9 most populations from busy ports show genetic admixture, while most populations from idle ports are genetically clustered (compare with <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.g003" target="_blank">Fig 3</a>).</p

Results of regression models.

<p>In all cases pairwise Fst is the dependent variable. Bold indicates P<0.01 for Pearson and P<0.001 for multiple linear regression.</p><p>¹Predictors excluded before running the model because the square root of Variance Inflation Factor (VIF) was >10.</p><p>²Predictors included in the model, but dropped by the stepwise analysis.</p><p>³Regression coefficients of the predictors confirmed by the model. Refer to <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.t002" target="_blank">Table 2</a> for detailed description of the predictors.</p><p>Results of regression models.</p

Three-dimensional scatter plot with regression plane that visualizes the effect of the variables called “Density” and “Cargo” on pairwise Fst values.

<p>Both predictors are negatively correlated to Fst and the relative regression coefficients are very low in absolute value. This means that a remarkable increase in Cargo and Density is necessary to cause a unit decrease in Fst values. The interpretation is that where cargo shipments are intense and human population is dense <i>Ae</i>. <i>aegypti</i> are more genetically similar. This suggests an influence of human transportation on mosquitos’ migration. Refer to <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.t002" target="_blank">Table 2</a> for detailed description of the variables.</p

Principal component analysis used to summarize seven variables related to port size and connectivity; plot of the first two PCs.

<p>Red arrows represent the vectors of the seven variables and each point in the plot is a port (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.g001" target="_blank">Fig 1</a> and <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.t001" target="_blank">Table 1</a>). The direction of principal component 1 (PC1) is almost opposite to the variables and it explains 74% of the total variance in the dataset; therefore, ports with low values of PC1 were considered big and highly connected (and vice versa). Refer to <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.t002" target="_blank">Table 2</a> for a detailed description of each variable.</p

Map of the sites where <i>Ae</i>. <i>aegypti</i> were collected.

<p>For detailed populations information refer to <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.t001" target="_blank">Table 1</a>.</p