-1計畫性核醣體轉譯軌道移轉（-1 programmed Ribosomal frameshifting, -1PRF）是病毒經常使用的一種特殊轉譯機制，該機制允許病毒在轉mRNA時移轉到另一個轉譯軌道 (reading-frame)上，也就是說，病毒可以用一條mRNA轉譯出一種以上的蛋白質。而轉譯軌道移轉的起始位置一般由一個滑動序列以及接在滑動序列後的特殊RNA二級結構所組成。這種轉譯機制，常見於病毒，如黃病毒(flavivirus)和SARS病毒，以及其他生物體，如大腸桿菌中。而本文的主要研究對象–茲卡病毒(Zika virus)，屬於黃病毒(flavivirus)的一種，我們懷疑其轉譯也可能利用這種轉譯機制。若病毒學家能設計專一性的藥物來結合上述的特殊RNA二級結構，不論是使結構更加穩定或更加鬆散，就可以影響病毒軌道移轉效率，進而達成消滅病毒的效果。而這首要工作就是能夠有準確的軟體來預測轉譯軌道移轉的起始位置，包含接在滑動序列後能形成特殊RNA二級結構的序列位置。在這樣的動機下，我們提出了一種新的演算法來找尋基因組中的-1PRF特徵，包括找尋開放閱讀框架（Open reading frames），滑動序列以及滑動序列後特殊RNA二級結構的位置。
結果顯示，我們的軟體PRF-Hunter (https://dyn.life.nthu.edu.tw/PRFH/) 能夠準確預測人類病毒中的-1PRF信號位置並將其排在所有類似訊號中的第一位，而目前已發表的最佳預測軟體KnotInFrame在我們的資料集(data sets)中，僅能部分做到。我們亦針對軟體在茲卡病毒株MR766中預測的-1PRF序列以同位素標定(35S)的體外轉譯軌道移轉檢測法(in vitro frameshifting assay)來測試序列有無-1PRF的發生，結果顯示，我們測試的預測序列確實能誘導-1PRF之發生。

-1 programmed Ribosomal frameshifting (-1PRF) is a special translation mechanism often utilized by viruses. The mechanism allows the viruses to switch into another reading frame during translation. In other words, viruses can translate more than one protein product from a given mRNA containing the -1PRF signal. The starting position of the frameshift signal generally consists of a slippery sequence and a special mRNA secondary structure following the slippery sequence. Such a translation mechanism is common in viruses such as flavivirus and SARS viruses, as well as in other organisms such as E. coli. Zika virus, belonging to flavivirus, is also suspected to involve such a mechanism during translation. If specific drugs that bind aforementioned PRF-driven RNA secondary structures can be designed, no matter to make the structure more stable or looser, they could perturb the PRF efficiency and therefore inhibit the viral replication. To make this possible, the first measure is to accurately predict the starting position of the PRF signal, including the location of the sequence that forms the specific RNA secondary structure following the slippery sequence. Given this motive, we herein propose a new algorithm to locate the -1PRF signals in the genome, including determination of the longest open reading frames as well as locating/ranking the slippery sequences and the specific RNA secondary structures following which.
The results show that our software PRF-Hunter (https://dyn.life.nthu.edu.tw/PRFH/) can accurately predict the position of the -1PRF signal in human viruses and rank it at the top among other similar signals. On the other hand, the best predictor ever published, KnotInFrame, can only achieve the same for a minor population of the examined dataset. One of the main reasons is that PRF-Hunter can predict the translational frame for the slippery sequence but KnotInFrame cannot; hence many false positives resulting from the latter. We also used in vitro cell-free frameshifting assay with radioactive 35S isotope-labeling to verify PRF-Hunter-predicted -1PRF signals in the Zika virus strain MR766.

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