Answers to question Lecture 26

Answers to question Lecture 26 - Questions for Lecture 26:...

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Questions for Lecture 26: Genetic screen for HIV-infectivity 1) To examine at what step Rab6 is required for HIV infection, Rab6 knockdown cells were infected with either (1) normal HIV (which binds to CD4) or (2) HIV with a virion surface that binds to a different human cell receptor. Only normal HIV had reduced infectivity, while HIV entry via a different receptor produced a normal infection level. In the same assay, what result would you expect with the TNPO3 knockdown? I presented a crude pathway for early HIV infection: Cell surface Membrane Reverse Nuclear binding ---> fusion ---> transcription ---> import Provirus Knockdown of TNPO3 was shown to affect some step after reverse transcription and before HIV provirus integration (because provirus integration was suppressed in the TNPO3 knockdown, but cytoplasmic reverse transcriptase activity was normal). We anticipate that any step prior to reverse transcriptase (RT) activity (and responsible for RT in the cytoplasm) would likewise be normal. Now to answer the question, HIV infectivity would appear no different regardless of whether we infected with TNPO3 knockdown with HIV (which binds to CD4) or HIV with a virion surface that binds to a different. If the assay measured a step before the TNPO3 block, both virion forms would appear to have normal infectivity. If the assay were a step after the TNPO3 block, both virion forms would suppressed. 2) TNPO3 knockdown cells were tested for reverse transcriptase (RT) activity in the cytoplasm after infection. The RT activity was normal. What if the RT activity were, instead, reduced compare to the negative control (Luciferase knockdown). What step(s) are probably affected by TNPO3 knockdown?
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Answers to question Lecture 26 - Questions for Lecture 26:...

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