Foamy viruses are retroviruses whose Pol protein is synthesized without Gag from a spliced mRNA. Unlike orthoretroviruses, reverse transcription occurs during viral assembly, leading to DNA-containing virions. When prototype foamy virus Pol is expressed as an orthoretroviral-like Gag-Pol fusion protein, reverse transcription also occurs late in viral replication, as measured by the timing of reverse transcriptase sensitivity to the inhibitor 3'-azido-3'deoxythymidine (AZT). Thus, timing of reverse transcription is intrinsic to Pol itself.
Dana L Jackson, Eun-Gyung Lee, Maxine L Linial. Expression of prototype foamy virus pol as a Gag-Pol fusion protein does not change the timing of reverse transcription. Journal of virology. 2013 Jan;87(2):1252-4
PMID: 23135709
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