In vitro and in vivo activity of anti-retroviral compounds attacking NC zinc fingers

Retroviral nucleocapsid (NC) proteins contain one or two zinc fingers (ZFs) consisting of a Cys(X)(2)Cys(X)(4)His(X)(4)Cys (CCHC) peptide motif that coordinates Zn(II). Mutational and biochemical analyses have shown that NC ZFs are required for viral replication and are directly involved in multiple stages of viral replication cycle including genomic RNA encapsidation, virus maturation, and the early infection process. We have previously shown that Cys thiols in retroviral NC ZFs are susceptible to chemical attack by a wide variety of chemical compounds which can inactivate whole virus. Many of these compounds are non-toxic and thus have the potential to serve as lead compounds for the development of a new class of therapeutic anti-retrovirals. To continue this exploration we have developed methods to; (i) identify selected compounds that react preferentially with the NC protein; (ii) determine the initial site of attack on the NC protein; (iii) explore the influence of nucleotide binding on the initial reactivity; (iv) measure the rate of virus killing; (v) and developed two whole animal model systems (MuLV infected mice and SIV infected monkeys) for testing anti-viral activity. These results show that at least one compound has been identified which has an enhanced reactivity with the target NC protein, inactivates whole virus (SIV, HIV-1 and MuLV), react selectively with the whole viral NC protein, is non-toxic, can be taken orally and reduces viral replication in the MuLV/mouse model and in the SIV/monkey model. These results strongly support the suggestion that the reactivity of the NC protein CCHC ZFs can be exploited to develop a new class of anti-retroviral compounds that may find therapeutic applications.

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