CNRS UMR7212, Inserm U944, Université Paris Diderot, Institut Universitaire d'Hématologie, Paris, France.
PLoS One. 2010 Jun 11;5(6):e11023. doi: 10.1371/journal.pone.0011023.
Although viral RNA constitutes the majority of nucleic acids packaged in virions, a late occurring step of reverse transcription leads to the presence of infectious viral cDNA in foamy virus particles. This peculiarity distinguishes them from the rest of the retroviral family.
To evaluate the respective contribution of these viral nucleic acids in the replication of foamy viruses, their fate was studied by real-time PCR and RT-PCR early after infection, in the presence or in the absence of AZT. We found that an early reverse transcription step, which occurs during the first hours post-entry, is absolutely required for productive infection. Remarkably, sensitivity to AZT can be counteracted by increasing the multiplicity of infection (moi). We also show that 2-LTR circular viral DNA, which appears as soon as four hours post-infection, is transcriptionally competent.
Taken together, our data demonstrate that an early reverse transcription process, which takes place soon after viral entry, is indispensable for infectivity of FVs at low moi, when the amount of DNA-containing particles is not sufficient to lead to a productive infection. This study demonstrates a key role of the packaged viral RNA in the foamy virus infection, suggesting that the replication of this virus can be achieved by involving either viral DNA or RNA genome, depending on the condition of infection.
尽管病毒 RNA 构成了病毒粒子中包装的大多数核酸，但反转录的一个晚期步骤导致了泡沫病毒粒子中传染性病毒 cDNA 的存在。这种特殊性将它们与逆转录病毒家族的其他成员区分开来。
为了评估这些病毒核酸在泡沫病毒复制中的各自贡献，我们通过实时 PCR 和 RT-PCR 在感染后早期，在存在或不存在 AZT 的情况下，研究了它们的命运。我们发现，一个早期的反转录步骤，发生在进入后的头几个小时内，是产生活感染所必需的。值得注意的是，通过增加感染复数（moi）可以抵消 AZT 的敏感性。我们还表明，2-LTR 环状病毒 DNA 早在感染后四小时就出现了转录能力。
总之，我们的数据表明，在低 moi 时，病毒进入后很快发生的早期反转录过程对于 FV 的感染性是必不可少的，此时含 DNA 颗粒的数量不足以导致产生活感染。本研究证明了包装的病毒 RNA 在泡沫病毒感染中的关键作用，表明该病毒的复制可以通过涉及病毒 DNA 或 RNA 基因组来实现，具体取决于感染条件。
