Bevirimat is an anti-HIV drug derived from a betulinic acid-like compound, first isolated from Syzygium claviflorum, a Chinese herb. It is believed to inhibit HIV by a novel mechanism, so-called maturation inhibition. Like protease inhibitors, bevirimat and other maturation inhibitors interfere with protease processing of newly translated HIV polyprotein precursor, called gag. Gag is an essential structural protein of the HIV virus. Gag undergoes a chain of interactions both with itself and with other cellular and viral factors to accomplish the assembly of infectious virus particles. HIV assembly is a two-stage process involving an intermediate immature capsid that undergoes a structurally dramatic maturation to yield the infectious particle. This alteration is mediated by the viral protease, which cleaves the Gag polyprotein precursor, allowing the freed parts to reassemble to form the core of the mature virus particle.
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