本文選題：瘧原蟲　切入點：混合感染　出處：《廈門大學(xué)》2009年碩士論文　論文類型：學(xué)位論文

【摘要】： 混合感染在瘧原蟲感染中是一種極為普遍的現(xiàn)象,混合感染發(fā)生后,宿主-寄生蟲系統(tǒng)會發(fā)生一系列比單獨感染時更為復(fù)雜的相互作用,可能對瘧原蟲毒力進(jìn)化產(chǎn)生重要的影響。另一方面,可能會對宿主免疫應(yīng)答的產(chǎn)生及效應(yīng)強(qiáng)度產(chǎn)生重要的影響。由此看來,為了深入闡明瘧原蟲感染宿主機(jī)體免疫應(yīng)答的機(jī)制,以對疫苗開發(fā)做出更好的指導(dǎo)作用,加大開展混合感染對于宿主免疫系統(tǒng)應(yīng)答的影響是非常必要的。 為了對同種而基因型有差異的蟲株進(jìn)行分型與定量,我們采用了實時熒光定量PCR(RTQ-PCR)的方法。本研究中找到了合適的分子標(biāo)記標(biāo)識約氏瘧原蟲兩個蟲株17XNL與265BY,運(yùn)用相對定量來對混合感染進(jìn)程中兩個蟲株的比例進(jìn)行了實時監(jiān)測。實驗結(jié)果表明兩種毒力不同的蟲株在宿主體內(nèi)發(fā)生競爭作用時,毒力強(qiáng)的一方總是占據(jù)著主動地位,它們總能在競爭中獲勝。當(dāng)17XNL:265BY=5:5感染小鼠時,265BY在群體中在12天時已經(jīng)占據(jù)了81%的比例。 結(jié)合感染進(jìn)程中宿主存活率,原蟲血癥水平等數(shù)據(jù),我們能比較充分地了解兩種毒力不同的蟲株混合感染時的生存競爭狀況及其宿主免疫反應(yīng)的表征。當(dāng)混合感染發(fā)生時,蟲株群體數(shù)量的變化并不簡單等同于兩種蟲株單獨感染時數(shù)量的簡單疊加,不論蟲株毒力強(qiáng)弱抑或混合感染時蟲株的比例不同,其中每一種蟲株都受到了不同程度的抑制作用。以初始感染比例17XNL:265BY分別為1:9和9:1為例,前者在14天時17XXL被抑制的程度達(dá)到了98%,而后者中265BY在14天時被抑制的程度為60%。雖然目前還不清楚這種動態(tài)變化的發(fā)生與宿主免疫系統(tǒng)影響的具體關(guān)聯(lián),但是本實驗為下一步探尋宿主免疫應(yīng)答的細(xì)胞因子的變化,闡明保護(hù)性和病理性免疫應(yīng)答動態(tài)平衡的調(diào)控機(jī)制奠定了一定的基礎(chǔ)。 本論文亦以廈門某醫(yī)院一位自然感染間日瘧原蟲患者的血液樣本為研究材料,提取基因組DNA,擴(kuò)增coxⅢ基因序列,并以之作為分子標(biāo)記,構(gòu)建系統(tǒng)發(fā)生樹,探討了coxⅢ是否可以作為瘧原蟲屬不同種之間分子系統(tǒng)進(jìn)化研究的合適基因。通過本文中選取的瘧原蟲屬13個種加上本實驗獲得的間日瘧原蟲種,依據(jù)coxⅢ基因建立的系統(tǒng)進(jìn)化樹來看,它可以很好地反映瘧原蟲屬不同物種之間的遺傳親緣關(guān)系。今后的研究中可以利用coxⅢ這一有效的工具開展寄生蟲生物分類及系統(tǒng)發(fā)育關(guān)系的研究工作。
[Abstract]:Mixed infection is an extremely common phenomenon in Plasmodium infection, where a host-parasite system has a series of more complex interactions than a single infection. May have an important impact on the virulence evolution of Plasmodium. On the other hand, it may have an important effect on the generation and intensity of host immune response. Therefore, in order to further elucidate the mechanism of immune response of host body infected by Plasmodium, In order to provide better guidance for vaccine development, it is necessary to increase the effect of mixed infection on host immune system response. In order to type and quantify the strains of the same species with different genotypes, We used the method of real-time fluorescence quantitative PCRQ-PCR.A suitable molecular marker was found to identify two plasmodium strains 17XNL and 265BY. the proportion of two strains in the process of mixed infection was measured by relative quantification. The results showed that when two different virulence insect strains compete in the host, The virulent side always takes the initiative, and they always win the competition. When 17XNL: 265BY5: 5 infects the mice, 265BY already accounts for 81% of the population at 12 days. Based on the data of host survival rate and protozoemia level in infection process, we can fully understand the survival competition and host immune response of two different virulence strains in mixed infection. The variation of population number is not simply equivalent to the simple superposition of the two strains when they are infected alone, regardless of whether the virulence or the proportion of mixed strains are different. For example, the initial infection ratios of 17XNL: 265BY were 1: 9 and 9: 1, respectively. The former was inhibited by 17XXL at the 14th day to 98 percent, while the latter by 265BY was inhibited to the extent of 60 percent at the 14th day, although it is not clear whether this dynamic change is related to the host immune system. However, this study laid a foundation for further exploring the changes of cytokines in host immune response and elucidating the regulatory mechanism of dynamic balance between protective and pathological immune responses. In this paper, a blood sample from a naturally infected Plasmodium vivax patient in a hospital in Xiamen was used to extract genomic DNA, amplify the sequence of cox 鈪，

本文編號：1578666