JAC Advance Access published online on February 27, 2007
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkm011
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Inhibition of HIV-1 replication in macrophages by a heterodinucleotide of lamivudine and tenofovir
1 Institute of Biochemistry ‘G. Fornaini’, University of Urbino ‘Carlo Bo’, 61029 Urbino, Italy 2 Department of Chemical Sciences, University of Camerino, 62032 Camerino, Italy 3 Department of Experimental Medicine, University of Rome ‘Tor Vergata’, 00133 Rome, Italy
Received 19 September 2006; returned 15 November 2006; revised 21 December 2006; accepted 15 January 2007
* Correspondence address. Istituto di Chimica Biologica ‘G. Fornaini’, Università degli Studi di Urbino ‘Carlo Bo’, Via Saffi, 2-61029 Urbino, Italy. Tel: +39-722-305201; Fax: +39-722-320188; E-mail: l.rossi{at}uniurb.it
Objectives: (i) To generate a new heterodinucleotide (3TCpPMPA) comprising the drugs lamivudine and tenofovir which have been shown to act synergistically and (ii) to protect macrophages from ‘de novo’ HIV-1-infection through its administration.
Methods: 3TCpPMPA was obtained by coupling the morpholidate derivative of tenofovir with the mono n-tri-butylammonium salt of lamivudine 5'-monophosphate. Stability and metabolism were evaluated in vitro and in vivo in mice. 3TCpPMPA was encapsulated into autologous erythrocytes by a procedure of hypotonic dialysis, isotonic resealing and reannealing. 3TCpPMPA-loaded erythrocytes were modified to increase their phagocytosis by human macrophages. Macrophages were infected by HIV-1Ba-L and inhibition of HIV-1 replication was assessed by HIV p24gag quantification.
Results: Pharmacokinetic studies in mice revealed a rapid disappearance of the heterodinucleotide from circulation (t1/2 = 15 min) without any advantage compared with the administration of single drugs. Adding free 3TCpPMPA to macrophages (18 h), a 90% inhibition of viral replication up to 35 days post-treatment was achieved, while only a 60% inhibition was obtained by the combined treatment 3TC and (R)PMPA. When 3TCpPMPA was selectively targeted to the macrophage compartment by a single addition of loaded erythrocytes, the protection of macrophages from ‘de novo’ infection (99% protection 3 weeks post-treatment) was nearly complete.
Conclusions: Erythrocytes loaded with 3TCpPMPA and modified to increase their phagocytosis are able to protect macrophages from ‘de novo’ HIV-1 infection. 3TCpPMPA acts as an efficient antiviral pro-drug that, once inside macrophages, can be slowly converted into 3TCMP and (R)PMPA protecting these cells for a longer period of time.
Key Words: phagocytes , nucleoside analogues , HIV/AIDS , drug-delivery