The Molecules of HIV

Note: this site last updated in 2006

integration into the host genome

An article from "The Molecules of HIV" (c) Dan Stowell

The preintegration complex (the RNA and protein of the HIV core, plus cellular proteins) moves into the cell's nucleus. (It passes through a pore in the nuclear membrane - the nuclear membrane has a number of pores to allow substances to pass in and out of the nucleus.)

Once inside the nucleus the HIV integrase enzyme can begin to work on the HIV DNA which is being produced. Integrase catalyses the partial cleaving of the end of the DNA (the two strands of DNA are prised apart, as you might prise apart an attached piece of velcro) - to leave the HIV DNA with "sticky ends". It also makes a cut in the cell's DNA (essentially it makes the cut anywhere, but some specific points in the cell's DNA are preferred targets) leaving two more "sticky ends". The HIV and cellular DNA can then be stuck together, effectively making HIV's genes part of the cell's genome.

As a further indication of how sloppy HIV's mechanisms can be, the joins where HIV DNA and cell DNA have been connected are often not perfect (there may be small breaks in one or other of the two strands of the DNA helix). However, HIV can here rely on the cell's own mechanisms to fix these problems. Human cells have a lot of error-correction and DNA repair mechanisms and will fix defective bits of their chromosomes (completely "unaware" that the defects are because of a surreptitious insertion).

With the viral genes inserted into the host genome, either HIV can lie low, or can begin the RNA%20and%20protein">production of more HIV RNA and protein...

Written by
Dan Stowell

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