Although the peptide was detectable in the chimeric livers of these mice, no selective enrichment in the transplanted PHH was observed.21 To investigate whether HBVpreS/2-48myr is specifically directed to the liver we performed in vivo distribution studies of HBVpreS/2-48myr-y-125I in NRMI mice (Fig. 2A). To control specificity we included a randomized preS1-peptide (HBVpreS/2-48_scrstea-y-125I) (Fig. 2B).20 As depicted in Fig. 2A, 5 minutes after intravenous application of ∼45 μg HBVpreS/2-48myr-y-125I,

an almost exclusive accumulation of radioactivity in the liver was observed (>83%). The signal ceases slowly and was still detectable with ∼34% of the injected dose 24 hours postinjection (p.i.). The kinetic analysis revealed a half-life time of ∼18 hours. Apart from the pronounced liver accumulation we noticed a minor signal within the first 4 hours in the bladder. The signal was lost between 4 GSI-IX in vivo hours and 6 hours p.i., probably through renal clearance between repeated anesthesia. The percentage of radioactivity in the bladder after 4 hours was 16%. In contrast to the hepatic enrichment of HBVpreS/2-48myr-y-125I, intravenous

injection of the randomized HBVpreS/2-48scrstea-y-125I resulted in disperse body distribution. During the first anesthesia (0-4 hours) a higher percentage of the mutant peptide appeared in the bladder (30%). Six hours p.i. most of the radioactivity was eliminated; at 24 A-769662 order hours p.i. no peptide was detectable. Accordingly, the radioactivity was renally filtered with a half-life of about 4 hours. This was confirmed by the autoradiographic analysis of the corresponding liver sections (Fig. 2C). While an equal distribution of radioactivity in liver lobules was detectable 24 hours p.i. after application of the GNE-0877 wildtype peptide, no signal appeared for the mutant. This implies that the HBVpreS-lipopeptide accumulation in the

liver requires the integrity of the HBVpreS1-sequence, indicating a sequence-specific binding of the peptide to an HBVpreS-receptor. To map the sequence required for the accumulation of HBVpreS/2-48myr in the mouse liver we performed in vivo distribution analyses using the iodinated peptides depicted in Fig. 3D. These peptides have been characterized with respect to their ability to inhibit HBV infection.20 The results are summarized in the right column of Fig. 3D. To obtain quantitative measures for their ability to accumulate in different organs we injected the labeled peptides intravenously and sacrificed three mice per point in time (10 minutes, 1 hour, 4 hours, and 24 hours), extracted the intestine, brain, muscle, kidney, liver, spleen, lung, heart, and blood, counted the organ-associated radioactivity, and calculated the percentage of the injected dose per gram tissue (%ID/g). As shown in Fig. 3A, a modified (Q46K), genotype C-derived preS1-lipopeptide (Myrcludex B) locates with 71.