澳大利亞科學(xué)家在南極的湖里發(fā)現(xiàn)了一種新的噬病毒體（virophage），這是科學(xué)家繼Sputnik和Mavirus之后,，迄今發(fā)現(xiàn)的第三種噬病毒體,。新發(fā)現(xiàn)有助于科學(xué)家更好地理解這類病毒生物功能的復(fù)雜性，并解釋這類病毒為何能迅速變異以致很難用藥物或疫苗抵御它們,。研究發(fā)表在最新出版的美國《國家科學(xué)院院刊》上,。
新南威爾士大學(xué)微生物學(xué)家李嘉圖·卡維留里領(lǐng)導(dǎo)的科研小組從南極有機(jī)湖中發(fā)現(xiàn)了這種新病毒，其基因序列與首個(gè)噬病毒體Sputnik非常類似,，因此將其歸為噬病毒體類,，并命名為“有機(jī)湖噬病毒體（OLV）”。
科學(xué)家在藻DNA病毒的基因序列中發(fā)現(xiàn)了OLV,，藻DNA病毒是一種攻擊海藻的大病毒,，而OLV則能通過攻擊這些藻DNA病毒使海藻躲過藻DNA病毒的攻擊并“撒歡似地繁殖”。
2008年,，法國科學(xué)家發(fā)現(xiàn),，從冷凍庫分解出來的巨型病毒被一個(gè)較小的病毒Sputnik感染，Sputnik能從宿主病毒和其他微生物身上“掠奪”基因,，達(dá)到顯著的基因混合效果,，由于這種生活方式類似于噬菌體，科學(xué)家將其稱為噬病毒體,，Sputnik因此成為人們發(fā)現(xiàn)的首個(gè)噬病毒體,。此前，人們只知道病毒能感染細(xì)菌，但Sputnik病毒是首個(gè)能感染其他病毒的例子,。
科學(xué)家當(dāng)時(shí)通過對海洋水域所進(jìn)行的宏基因組學(xué)研究發(fā)現(xiàn),，存在大量與巨病毒密切相關(guān)的基因序列，并認(rèn)為,，應(yīng)該有大量類似于Sputnik的噬病毒體存在,。
本月初，加拿大英屬哥倫比亞大學(xué)的微生物學(xué)家馬緹亞斯·菲舍和柯帝士·夏特爾宣布,，他們發(fā)現(xiàn)了第二種噬病毒體并將其命名為Mavirus,。據(jù)報(bào)道，這種病毒可以攻擊到目前為止發(fā)現(xiàn)的最大病毒CroV,，Mavirus只有在周圍有CroV時(shí)才活躍起來,，而CroV周圍出現(xiàn)Mavirus時(shí)，其傳染速度會(huì)降低,。研究人員推測,，Mavirus能通過竊取CroV的基因而快速繁殖。
第三種噬病毒體OLV的發(fā)現(xiàn)使得科學(xué)家更加堅(jiān)信,，在其他很多地方,，比如冰湖附近的水域中，都可能存在基因序列與OLV相同的噬病毒體,，未來科學(xué)家或許可以一一發(fā)現(xiàn),。目前，對噬病毒體的研究還處于起步階段,，研究結(jié)果將有助于科學(xué)家更好地理解這些病毒生物功能的復(fù)雜性,。（生物谷Bioon.com）
生物谷推薦原文出處：
Proceedings of the National Academies of Sciences doi:10.1073/pnas.1018221108
Virophage control of antarctic algal host–virus dynamics
Sheree Yaua, Federico M. Lauroa, Matthew Z. DeMaerea, Mark V. Browna, Torsten Thomasa,b, Mark J. Rafteryc, Cynthia Andrews-Pfannkochd, Matthew Lewisd, Jeffrey M. Hoffmand, John A. Gibsone, and Ricardo Cavicchiolia,1
Viruses are abundant ubiquitous members of microbial communities and in the marine environment affect population structure and nutrient cycling by infecting and lysing primary producers. Antarctic lakes are microbially dominated ecosystems supporting truncated food webs in which viruses exert a major influence on the microbial loop. Here we report the discovery of a virophage (relative of the recently described Sputnik virophage) that preys on phycodnaviruses that infect prasinophytes (phototrophic algae). By performing metaproteogenomic analysis on samples from Organic Lake, a hypersaline meromictic lake in Antarctica, complete virophage and near-complete phycodnavirus genomes were obtained. By introducing the virophage as an additional predator of a predator–prey dynamic model we determined that the virophage stimulates secondary production through the microbial loop by reducing overall mortality of the host and increasing the frequency of blooms during polar summer light periods. Virophages remained abundant in the lake 2 y later and were represented by populations with a high level of major capsid protein sequence variation (25–100% identity). Virophage signatures were also found in neighboring Ace Lake (in abundance) and in two tropical lakes (hypersaline and fresh), an estuary, and an ocean upwelling site. These findings indicate that virophages regulate host–virus interactions, influence overall carbon flux in Organic Lake, and play previously unrecognized roles in diverse aquatic ecosystems.
