Elucidating the Mechanisms of Reverse Transcription and Recombination

频繁的重组对HIV-1群体的多样性有很大贡献。我们已经研究了HIV-1重组的多个方面，包括产生亚型间重组体的机制，这些重组体在当前的艾滋病流行中发挥着越来越重要的作用。通过比较亚型内和亚型间HIV-1重组，我们发现不同HIV-1亚型之间的序列多样性减少了交叉事件，降低了重组体的复制适应性，从而导致新生成的嵌合病毒的丢失。另外，二聚化起始信号（DIS），即病毒基因组5'非翻译区的6-nt回文序列，通过两种不同的机制影响HIV-1重组频率：首先，DIS的同一性通过决定病毒RNA共包装的频率影响具有不同DIS的基因型之间重组体的产生;第二，共包装RNA中的不一致DIS序列可进一步减少病毒基因组5 ′端的交换并产生重组梯度。由于HIV-1被认为是由两种不同的灵长类慢病毒产生的重组体，我们还研究了不同艾滋病病毒之间的重组。我们证明，重组可以发生在远亲HIV-1和HIV-2之间，以及O组和M组HIV-1变异体之间，尽管重组率很低。这些研究揭示了产生HIV-1基因组多样性和潜在的新型嵌合病毒的重组机制。我们在这个项目中的努力集中在逆转录的关键步骤，包括负链DNA转移和宿主限制因子如何影响HIV复制。我们还在研究A亚型病毒之间的重组，以及导致新产生的重组体失去复制适应性的机制。这些研究将揭示对HIV-1复制机制的见解。[对应于2011年10月艾滋病毒耐药性项目现场访问报告中的Hu项目1]

Frequent recombination contributes significantly to the diversity of the HIV-1 population. We have studied multiple aspects of HIV-1 recombination, including the mechanisms that generate intersubtype recombinants, which are playing an increasingly important role in the current AIDS epidemic. By comparing intra- and intersubtype HIV-1 recombination, we have found that the sequence diversity between different HIV-1 subtypes decreases the crossover events and reduces the replication fitness of the recombinants, thereby causing the loss of newly generated chimeric viruses. Additionally, the dimerization initiation signal (DIS), a 6-nt palindromic sequence in the 5' untranslated region of the viral genome, affects the HIV-1 recombination frequency by two separate mechanisms: first, the identity of the DIS affects the generation of recombinants between genotypes with different DIS by dictating the frequency of viral RNA copackaging; second, discordant DIS sequences in the copackaged RNAs can further decrease crossovers at the 5' end of the viral genome and generate a recombination gradient. As HIV-1 is thought to be a recombinant generated from two distinct primate lentiviruses, we also studied recombination between different AIDS viruses. We demonstrated that recombination can occur between distantly related HIV-1 and HIV-2, as well as group O and group M HIV-1 variants, albeit at low rates. These studies revealed insights into the recombination mechanisms that generate diversity in the HIV-1 genome and potentially novel chimeric viruses. Our efforts in this project are focused on critical steps of reverse transcription including minus-strand DNA transfer and how host restriction factors can affect HIV replication. We are also studying recombination between subtype A viruses and mechanisms that cause a loss of replication fitness in newly generated recombinants. These studies will reveal insights into the replication mechanisms of HIV-1. [Corresponds to Hu Project 1 in the October 2011 site visit report of the HIV Drug Resistance Program]