AIDS研究發(fā)展緩慢的部分原因在于研發(fā)的疫苗如同“圓洞中的香椿”找不到合適的動物模型檢測療效。HIV-1病毒不能在猴細(xì)胞中進(jìn)行復(fù)制,，因此研究人員一直利用一種叫做短尾猴免疫缺陷病毒（macaque version of simian immunodeficiency virus,，SIVmac）感染動物,，以期獲得用于檢測候選治療途徑或者候選疫苗療效的動物模型,，但最終得到的能夠有效抵御SIV的疫苗在人類臨床實(shí)驗(yàn)中效果并不顯著。最近,，洛克菲勒和Aaron Diamond 艾滋病研究中心的研究人員利用遺傳工程學(xué)和壓力篩選（forced adaptation,，生物通編者譯）的聯(lián)合療法，研制出一種新型AIDS病毒,，此病毒能夠在人細(xì)胞和猴細(xì)胞中快速復(fù)制,，有望改善疫苗研究。
Science雜志10月6日一篇文章中,，Retrovirology 實(shí)驗(yàn)室負(fù)責(zé)人Paul Bieniasz副教授對其與同事通過采用SIV病毒成分對HIV病毒的一小段結(jié)構(gòu)進(jìn)行改造而繞過靈長類細(xì)胞天然免疫性機(jī)制進(jìn)行了詳細(xì)描述,。（靈長類細(xì)胞的免疫機(jī)制能夠阻止HIV病毒在猴細(xì)胞中進(jìn)行復(fù)制）,。Bieniasz說：“整個過程看上去并不復(fù)雜，但是它花費(fèi)了我們兩年的時(shí)間,。”
Bieniasz與論文第一作者Theodora Hatziioannou合作，繞過了實(shí)驗(yàn)中遇到的兩大難題：首當(dāng)其沖的是在猴細(xì)胞中一種叫做TRIM5的蛋白,，此蛋白識別HIV-1衣殼,，但是不識別SIV的衣殼。首先將編碼HIV-1衣殼的基因更換為編碼SIVmac病毒衣殼的基因,，然后經(jīng)過幾輪壓力篩選,，Hatziioannou得到可以入侵猴細(xì)胞并逃逸TRIM5識別的HIV-1突變體。
第二道難關(guān)在于：宿主產(chǎn)生的APOBEC蛋白能夠引發(fā)入侵的病毒發(fā)生突變而將病毒殺死,，但是HIV-1能夠利用一種叫做Vif的蛋白破壞APOBEC而抵御宿主的攻擊,。猴APOBEC蛋白不受人類HIV-1病毒Vif蛋白影響。因此Hatziioannou為人類HIV-1病毒更換編碼SIV Vif 的基因,，經(jīng)過又一次壓力篩選后得到繁殖力旺盛的病毒株,。
研究人員定名最后得到的病毒株為simian tropic HIV (stHIV)，作為HIV-1的一種突變型,，雖然只與原代病毒有10％的差異,，但是能夠有效感染靈長類細(xì)胞，可用于檢測候選治療方案的療效,。Bieniasz說：“假如我們能夠在動物實(shí)驗(yàn)中使病毒發(fā)揮在培養(yǎng)組織中相似的功能,，就有可能改變目前ADIS疫苗和治療途徑的研究方法。”
Tweaking HIV. A newly engineered version of the AIDS virus, dubbed stHIV, replicates robustly in rhesus monkey cells.
The slow pace of AIDS research can be pinned, in no small part, on something akin to the square-peg-round-hole conundrum. The HIV-1 virus won’t replicate in monkey cells, so researchers use a monkey virus — known as SIVmac, or the macaque version of simian immunodeficiency virus — to test potential therapies and vaccines in animals. But therapies and vaccines that are effective on SIV don’t necessarily translate into human success.
Now, using a combination of genetic engineering and forced adaptation, researchers at Rockefeller and the Aaron Diamond AIDS Research Center have created a version of the AIDS virus that replicates vigorously in both human and monkey cells — an advance that has the potential to revolutionize vaccine research.
In a paper published in the last issue of Science, Paul Bieniasz, associate professor and head of the Laboratory of Retrovirology, describes how he and his colleagues maneuvered around the intrinsic immunity of primate cells by replacing just a few parts of the human virus — the ones responsible for blocking replication in monkey cells — with components from SIV. “Overall, the virus is a mixture of engineering and forced evolution,” Bieniasz says. “It sounds simple, in theory, but it took us two years to do.”
Bieniasz and Theodora Hatziioannou, a research scientist in the lab and the paper’s first author, had to overcome two major obstacles: the first was a protein called TRIM5 that, in monkeys, recognizes the outer shell or “capsid” of HIV-1 but not that of SIV. By swapping out the capsid region of the HIV-1 genome for that of the monkey virus, and then selectively growing the viruses that replicated most robustly, over several generations Hatziioannou created an HIV-1 mutant that could evade the monkey cells’ TRIM5 recognition.
Another bit of engineering was required to get around the second obstacle: APOBEC proteins produced by a host normally cause invading viruses to mutate so much that they can’t survive, but HIV-1 uses a protein called Vif to destroy APOBEC and prevent the attack. Monkey APOBEC proteins, however, aren’t susceptible to the human virus’s Vif. So Hatziioannou did another swap — the SIV Vif gene for the HIV one — and then another round of forced adaptation to create viruses that would multiply with vigor.
The researchers dubbed their end result simian tropic HIV (stHIV): a form of HIV-1 that only differs from the original by about 10 percent, but can effectively infect primate cells and be used to test potential therapies. “If we can make this virus work in animals the way it works in tissue culture, it will likely change the way that AIDS vaccine and therapeutics research is done,” Bieniasz says.
