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02639_3 UC-781 BLOCKS LOCALISED INFECTION AND CELL DISSEMINATION PATHWAYS WITHIN HUMAN CERVICAL TISSUE Watts, Patricia Background: In the absence of an effective vaccine, microbicides provide a female controlled method of preventing HIV-1 infection that could significantly reduce worldwide transmission rates. UC-781 is a highly potent and selective thiocarboxanilide non-nucleoside reverse transcriptase inhibitors (NNRTI) of HIV-1. The compound exhibits high affinity for viral reverse transcriptase and is hydrophobic in nature, characteristics desirable for a microbicide. Thus, UC781 has potential as a lead candidate in microbicide development for both vaginal and rectal application. We have tested the hypothesis that UC781 can blockade both the localized infection of human cervical tissue, and dissemination of the virus. Methods: In vitro activity and toxicity was determined by pretreatment of virus or target cells. The efficacy of UC781 to prevent localised mucosal infection and the potential uptake of infectious virus by migrating cells was assessed using an established ex-vivo, cervical explant model. Results: UC781 potently inhibited HIV replication in cervical tissue explants and the transfer of infectious virus from migratory cells to coculture cells. In cervical explants pretreated with UC781, protection against viral challenge was still detectable 6 days post drug treatment, suggesting a potent memory effect. Pretreatment of tissue explants also demonstrated significant inhibition of viral dissemination by migratory cells. This inhibition was shown to occur by means other than the inhibition of viral attachment. Conclusions: The NNRTI UC-781 demonstrates potent and prolonged activity against HIV-1 without being toxic to target cells. Thus, UC-781 is a promising candidate for continued pre-clinical and clinical development for use as a microbicide. Miss Patricia Watts |
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