125年前愛滋病毒早已現身 由黑猩猩傳播給人類 | 環境資訊中心
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125年前愛滋病毒早已現身 由黑猩猩傳播給人類

2008年10月07日
摘譯自2008年10月2日ENS美國,亞利桑那州,吐桑市報導;江昱均編譯;莫聞審校

愛滋病毒由黑猩猩傳播給人類 (圖片來源:David Schenfeld)最新研究指出,全球最為普及的HIV病毒病種早在1884年已在人類間互相傳遞,同時還提出1900年早期殖民非洲的都市化促使愛滋病流行。自1981年以來,超過2500萬人死於愛滋病,而現今至少有3億人罹患愛滋病。

這項研究預估愛滋病起源於1900年,較以往預估的1930年還要早,與中、西非洲地區都市中心的發展與崛起時間相符,而中、西非洲也是HIV-1病毒M組出現的地區。科學家相信,都市的成長和高風險行為可能是讓病毒猖獗的主要變因。

亞利桑那大學的生態與演化生物學副教授瓦若比(Michael Worobey)領軍的這項研究,同時也獲得隸屬國家衛生研究院(national Institutes of Health)的國立過敏與感染疾病研究中心(National Institute of Allergy and Infectious Diseases),以及大衛和露西爾•帕卡德基金會(David and Lucille Packard Foundation)補助。研究裡的各項發現將在最新一期的《自然》(Nature)期刊發表。

瓦洛比與其研究團隊檢驗細胞組織樣本,揭露世界上HIV-1病毒M組中次為久遠的基因序列可溯及至1960年。

這批科學家利用新近發展科技,從48年前蠟封的活體組織切片淋巴結中提取並復原HIV病毒基因碎片,這份活體組織切片來自剛果共和國首都金沙薩一位當時罹患愛滋的婦女。而已知最古老的HIV-1病毒M組的基因序列則是從一份1959年的男性血液樣本提取,這位男性同樣也來自金沙薩。

比較兩種病毒身上同一基因部位在1959年與1960年的結果顯示此兩者的共同祖先早在1900年就已經存在。

瓦若比解釋:「如今在歷史上我們首次能夠比較兩種相關的HIV古老病種。這將協助我們校準HIV病毒演化的速度,並且完善地推斷它何時開始傳染給人類,以多快的速度流行開來,以及哪些因素使它進入人體並成功地成為影響人類的病原體。」

瓦若比表示未來的研究方向將著重在復原更多樣本,同時集結殘缺不全的DNA和RNA序列,來構成更為清楚的HIV病毒進化史。

「我認為HIV病毒進化史已經漸露曙光,從人類經歷過的變遷可為HIV病毒的傳播尋得痕跡,這部歷史提醒我們有能力做出可逆轉這種流行病的改變。」

瓦若比表示:「說到HIV病毒的弱點,那就是它不容易傳播。透過更好的檢驗和預防,擴大抗逆轉錄病毒藥物治療使用,可以產生數種降低傳染的方法,同時迫使病毒滅絕。」他結論:「我們的研究結果顯示有理由讓我們保持這麼樂觀。」

HIV/AIDS Originated 125 Years Ago, Spread from Chimps to Humans
TUCSON, Arizona, October 2, 2008 (ENS)

New research indicates that the most pervasive global strain of HIV began spreading among humans as early as 1884, suggesting that growing urbanization in colonial Africa through the early 1900s set the stage for the current HIV/AIDS pandemic. More than 25 million people have died of AIDS since 1981, and at least 30 million people are living with the disease today.

The estimated period of origin, much earlier than the previous estimate of 1930, coincides with the establishment and rise of urban centers in west-central Africa where the pandemic HIV strain, HIV-1 group M, emerged.

The growth of cities and associated high-risk behaviors may have been the key change that allowed the virus to flourish, scientists believe.

The research, led by Michael Worobey, an assistant professor of ecology and evolutionary biology at the University of Arizona in Tucson, was co-sponsored by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, and the David and Lucile Packard Foundation. The findings are published in the current issue of the journal "Nature."

Worobey and his team screened a number of tissue samples and uncovered the world's second-oldest genetic sequence of HIV-1 group M, which dates from 1960.

Using newly developed techniques, the scientists recovered the 48-year-old HIV gene fragments from a wax-embedded lymph-node tissue biopsy from a woman in Kinshasa in the Democratic Republic of the Congo. The oldest known HIV-1 group M genetic sequence comes from a 1959 blood sample from a man, also from Kinshasa.

A comparison of the same genetic region in the 1959 virus and the 1960 virus provided additional evidence that the common ancestor of both viruses existed around 1900.

"Now for the first time we have been able to compare two relatively ancient HIV strains. That helped us to calibrate how quickly the virus evolved and make some really robust inferences about when it crossed into humans, how quickly the epidemic grew from that time and what factors allowed the virus to enter and become a successful human pathogen," Worobey explained.

Worobey said his future research will focus on recovering more samples and assembling the fragmented DNA and RNA sequences to form a clearer picture of HIV's history.

"I think the picture that has emerged here, where changes the human population experienced may have opened the door to the spread of HIV, is a good reminder that we can make changes now that could help reverse the epidemic," he said.

"If HIV has one weak spot, it is that it is a relatively poorly transmitted virus. From better testing and prevention, to wider use of antiretroviral drug therapy, there are a number of ways to reduce transmission and force this virus back into extinction," Worobey said. "Our results suggest that there are reasons for such optimism."

全文及圖片詳見:ENS