Previously, we generated a murine monoclonal antibody (mAb), KR127, that recognizes amino acids (aa) 37-45 of the preS1 of hepatitis B virus (HBV). In this study, we have constructed a humanized version of KR127 and evaluated its HBV-neutralizing activity in chimpanzees. A study chimpanzee was given a single intravenous dose of the humanized antibody, followed by intravenous challenge with adr subtype of wild type HBV, while a control chimpanzee was only challenged with the virus. The result showed that the study chimpanzee did not develop HBV infection during 1 year, while the control chimpanzee was infected, indicating that the humanized antibody exhibited in vivo virus-neutralizing activity and thus protected the chimpanzee from HBV infection. In addition, the humanized antibody bound to the preS1 of all subtypes of HBV. We first demonstrate that an anti-preS1 mAb can neutralize HBV infection in vivo. This humanized antibody will be useful for the immunoprophylaxis of HBV infection.

The dimorphic transition of yeast to the hyphal form is regulated by the mitogen-activated protein kinase and cyclic AMP-dependent protein kinase A pathways in Saccharomyces cerevisiae. Signaling pathway-responsive transcription factors such as Ste12, Tec1, and Flo8 are known to mediate filamentation-specific transcription. We were interested in investigating the translational regulation of specific mRNAs during the yeast-tohyphal-form transition. Using polyribosome fractionation and RT-PCR analysis, we identified STE12, GPA2, and CLN1 as translation regulation target genes during filamentous growth. The transcript levels for these genes did not change, but their mRNAs were preferentially associated with polyribosomes during the hyphal transition. The intracellular levels of Ste12, Gpa2, and Cln1 proteins increased under hyphal-growth conditions. The increase in Ste12 protein level was partially blocked by mutations in the CAF20 and DHH1 genes, which encode an eIF4E inhibitor and a decapping activator, respectively. In addition, the caf20 and dhh1 mutations resulted in defects in filamentous growth. The filamentation defects caused by caf20 and dhh1 mutations were suppressed by STE12 overexpression. These results suggest that Caf20 and Dhh1 control yeast filamentation by regulating STE12 translation.The cellular morphology of diploid Saccharomyces cerevisiae frequently switches between the yeast and filamentous forms depending on nutritional signals (16). Several signal transduction modules, including the mitogen-activated protein kinase (MAPK) cascade and the cyclic AMP-dependent protein kinase A (PKA) pathway, are known to participate in this switch (14,21,31,36). The MAPK cascade involves Ste20, Ste11, Ste7, Kss1, and the transcription factors Ste12 and Tec1 (15,21,29,30). The PKA pathway involves Gpr1, Gpa2, Ras2, Tpk2, and the transcription factors Flo8 and Sfl1 (22,26,31,32). These signaling pathways control the transcription of a number of filamentation-specific genes, including FLO11 (19,23,29).Although the signaling pathways and transcriptional regulation of yeast filamentous growth have been studied in considerable detail, little is known about translational regulation related to the transition from the yeast to the filamentous form. In this study, we searched for specific mRNAs that are preferentially translated during the yeast-to-hyphal-form transition. Genome-wide analysis of mRNA translation profiles indicates that the loading of ribosomes onto individual mRNA species varies broadly (20, 28). The association of mRNA transcripts in polyribosomes reflects the rate of synthesis of their corresponding proteins (3, 45). By purifying polyribosome fractions and employing RT-PCR analysis, we found that the mRNA transcripts of STE12, GPA2, and CLN1 were preferentially recruited to polyribosomes during filamentation compared to during normal vegetative growth, even though their levels in the total cell extracts were not changed. Consistently, the protein levels of Ste12, Gpa2, and Cln1 also increased during...

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