We report a DNA shuffling-based approach for developing cell type-specific vectors through directed evolution. Capsid genomes of adeno-associated virus (AAV) serotypes 1-9 were randomly fragmented and reassembled using PCR to generate a chimeric capsid library. A single infectious clone (chimeric-1829) containing genome fragments from AAV1, 2, 8, and 9 was isolated from an integrin minus hamster melanoma cell line previously shown to have low permissiveness to AAV. Molecular modeling studies suggest that AAV2 contributes to surface loops at the icosahedral threefold axis of symmetry, while AAV1 and 9 contribute to two- and fivefold symmetry interactions, respectively. The C-terminal domain (AAV9) was identified as a critical structural determinant of melanoma tropism through rational mutagenesis. Chimeric-1829 utilizes heparan sulfate as a primary receptor and transduces melanoma cells more efficiently than all serotypes. Further, chimeric-1829 demonstrates altered tropism in rodent skeletal muscle, liver, and brain including nonhuman primates. We determined a unique immunological profile based on neutralizing antibody (NAb) titer and crossreactivity studies strongly supporting isolation of a synthetic laboratory-derived capsid variant. Application of this technology to alternative cell/tissue types using AAV or other viral capsid sequences is likely to yield a new class of biological nanoparticles as vectors for human gene transfer.

BackgroundIn China, high prevalence of HBV and HCV parallels with the growing epidemic of syphilis and HIV in the general population poses a great threat to blood safety. This study investigated the prevalence of serologic markers for transfusion transmissible infections (TTIs) among four Chinese blood centers.MethodsWe examined whole blood donations collected from January 2000 through December 2010 at four Chinese blood centers. Post-donation testing of TTIs (HIV, HBV, HCV and syphilis) were conducted using two different enzyme-linked immunosorbent assay kits for each seromarker. The prevalence of serologic markers for TTIs (%) was calculated and additional analysis was conducted to examine donor characteristics associated with positive TTIs serology.ResultsOf the 4,366,283 donations, 60% were from first-time donors and 40% were from repeated donors. The overall prevalence of HIV, HBsAg, HCV and syphilis was 0.08%, 0.86%, 0.51% and 0.47%, respectively. The prevalence profile of TTIs varied among different blood centers and appeared at relatively high levels. Overall, the prevalence of HBsAg and HCV demonstrated a decline trend among four blood centers, while the prevalence of HIV and syphilis displayed three different trends: constantly steady, continually increasing and declining among different centers.ConclusionsThis study reflects the risk of TTIs has been greatly reduced in China, but blood transfusion remains an ongoing risk factor for the spread of blood-borne infections, and further work and improvements are needed to strengthen both safety and availability of blood in China.

Recombinant adeno-associated virus (AAV) vectors expressing the cystic fibrosis transmembrane regulator (CFTR) gene have been used to deliver CFTR to the airway epithelium of cystic fibrosis (CF) patients. However, no significant CFTR function has been demonstrated likely due to low transduction efficiencies of the AAV vectors. To improve AAV transduction efficiency for human airway epithelium, we generated a chimeric AAV library and performed directed evolution of AAV on an in vitro model of human ciliated airway epithelium. Two independent and novel AAV variants were identified that contained capsid components from AAV-1, AAV-6, and/or AAV-9. The transduction efficiencies of the two novel AAV variants for human ciliated airway epithelium were three times higher than that for AAV6. The novel variants were then used to deliver CFTR to ciliated airway epithelium from CF patients. Here we show that our novel AAV variants but not the parental AAV provide sufficient CFTR delivery to correct the chloride ion transport defect to ~25% levels measured in non-CF cells. These results suggest that directed evolution of AAV on relevant in vitro models will enable further improvements in CFTR gene transfer efficiency and the development of an efficacious and safe gene transfer vector for CF lung disease.

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Peiminine, a compound extracted from the bulbs of Fritillaria thunbergii and traditionally used as a medication in China and other Asian countries, was reported to inhibit colorectal cancer cell proliferation and tumor growth by inducing autophagic cell death. However, its mechanism of anticancer action is not well understood, especially at the metabolic level, which was thought to primarily account for peiminine's efficacy against cancer. Using an established metabolomic profiling platform combining ultra-performance liquid chromatography/tandem mass spectrometry with gas chromatography/mass spectrometry, we identified metabolic alterations in colorectal cancer cell line HCT-116 after peiminine treatment. Among the identified 236 metabolites, the levels of 57 of them were significantly (p < 0.05) different between peiminine-treated and -untreated cells in which 45 metabolites were increased and the other 12 metabolites were decreased. Several of the affected metabolites, including glucose, glutamine, oleate (18:1n9), and lignocerate (24:0), may be involved in regulation of the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway and in the oxidative stress response upon peiminine exposure. Peiminine predominantly modulated the pathways responsible for metabolism of amino acids, carbohydrates, and lipids. Collectively, these results provide new insights into the mechanisms by which peiminine modulates metabolic pathways to inhibit colorectal cancer cell growth, supporting further exploration of peiminine as a potential new strategy for treating colorectal cancer.

Whether B19 NAT screening of blood and blood products should be launched in China, larger studies are needed to facilitate an informed decision.

Liver cirrhosis and hepatocellular carcinomas are major health problems of chronic hepatitis B virus (HBV) infection. To date, rare model has reproduced liver fibrosis associated with long-term HBV infection which in turn has hindered both the understanding of HBV biology and the development of new treatment options. Here, using adeno-associated virus serotype 8 (AAV8) mediated delivery of a 1.2-kb HBV genome, we successfully generated a chronic HBV infectious mouse model that presents the associated liver fibrosis observed following human infection. After AAV8/HBV1.2 vector administration, mice demonstrated effective HBV replication and transcription which resulted in HBV antigen expression and viremia over 6 months. Although no obvious acute inflammatory response was noted, these mice still developed chronic liver disease and hepatic fibrogenesis as demonstrated by increased ground glass-like hepatocytes, an increasing trend of collagen deposition and upregulated fibrosis markers, including type I collagen, type III collagen, tissue inhibitor of metalloproteinase (TIMP), and transforming growth factor-β1(TGF-β1). Taken together, AAV-mediated HBV gene delivery to the mouse liver, induced HBV persistent infection accompanied by liver fibrosis which can serve as a model for investigating the precise mechanisms underlying liver fibrosis following chronic HBV infection as well as for the potential development of novel therapeutics.

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