Targeting a recombinant adenovirus vector to HCC cells using a bifunctional Fab-antibody conjugate

We developed a specific adenoviral gene delivery system with monoclonal antibody (mAb) AF-20 that binds to a 180 kDa antigen highly expressed on human hepatocellular carcinoma (HCC) cells. A bifunctional Fab-antibody conjugate (2Hx-2-AF-20) was generated through AF-20 mAb crosslinkage to an anti-hexon antibody Fab fragment. Uptake of adenoviral particles and gene expression was examined in FOCUS HCC and NIH 3T3 cells by immunofluorescence; beta-galactosidase expression levels were determined following competitive inhibition of adenoviral CAR receptor by excess fibre knob protein. The chimeric complex was rapidly internalized at 37 degrees C, and enhanced levels of reporter gene expression was observed in AF-20 antigen positive HCC cells, but not in AF-20 antigen negative NIH 3T3 control cells. Targeting of recombinant adenoviral vectors to a tumor associated antigen by a bifunctional Fab-antibody conjugate is a promising approach to enhance specificity and efficiency of gene delivery to HCC.

PEGylation of adenovirus with retention of infectivity and protection from neutralizing antibody in vitro and in vivo

Replication-defective recombinant adenovirus (Ad) vectors are under development for a wide variety of gene therapy indications. A potential limiting factor associated with virus gene therapy requiring repeated treatment is the development of a humoral immune response to the vector by the host. In animal models, there is a dose-dependent rise in neutralizing antibodies after primary vector administration, which can preclude effective repeat administration. The strategy we have developed to circumvent the neutralization of adenovirus vectors by antibodies is to mask their surface by covalent attachment of the polymer polyethylene glycol (PEG). Covalent attachment of PEG to the surface of the adenovirus was achieved primarily by using activated PEG tresylmonomethoxypolyethylene glycol (TMPEG), which reacts preferentially with the epsilon-amino terminal of lysine residues. We show that the components of the capsid that elicit a neutralizing immune response, i.e., hexon, fiber, and penton base, are also the main targets for PEGylation. Several protocols for PEGylation of an adenovirus vector were evaluated with respect to retention of virus infectivity and masking from antibody neutralization. We show that covalent attachment of polymer to the surface of the adenovirus can be achieved with retention of infectivity. We show further that PEG-modified adenovirus can be protected from antibody neutralization in the lungs of mice with high antibody titers to adenovirus, suggesting that PEGylation will improve the ability to administer Ad vectors on a repeated basis.

Conformational analysis of 3-substituted-2,3,4,5-tetrahydro-1-benzoxepin by 1H and 13C nuclear magnetic resonance

2,3,4,5-Tetrahedro-1-benzoxepin (8) and its 3-substituted derivatives (9–13) have been studied by 1H and 13C dynamic nuclear magnetic resonance in a few solvent systems. The results show that, while 8 and its methyl derivative 9 exist solely in chair forms (C for 8 and Ce:Ca (96:4) for 9), the twist-boat (TB) conformation contributes significantly to the conformational equilibria of the derivatives 3-methoxy 10 (Ca:Ce:TB, 70:20:10), 3,3-dimethyl 11 (C:TB, 90:10), 3,3-methylmethoxy 12(Ca:Ce:TB, 89:4:7), and 3,3-dimethoxy 13 (C:TB, 92:8). The analysis of several factors (steric, electrostatic, and electronic) on the conformational behaviour of these molecules shows why the TB form is a viable conformational alternative to destabilized chair forms in this benzoxepin system.

The molecular conformations of 8,11-dimethyl-5,6-benzo-2-oxo-1,3,2-dioxathiepin and 4,4-dimethyl-5,6-benzo-2-oxo-1,3,2-dioxathiepin

The conformational properties of 8,11-dimethyl-5,6-benzo-2-oxo-1,3,2-dioxathiepin (5) and of 4,4-dimethyl-5,6-benzo-2-oxo-1,3,2-dioxathiepin (6) have been investigated using 1H and 13C dnmr as well as ir spectroscopy. Analysis of low temperature nmr spectra (down to −148 °C) and of S=O stretching vibrations in room temperature ir spectra indicates that the most stable conformations detected for solutions in CHF2Cl/CD2Cl2 (80:20) are TB (83%) and C-a (17%) for 5 and only the TB 7 for 6. Substituent effects of methyl groups at the peri and the benzylic positions on the conformational properties of the seven-membered sulfites are discussed.

The molecular conformations of the stereoisomers of 4-methyl-5,6-benzo-2-oxo-1,3,2-dioxathiepin and of the 4,7-dimethyl derivative

The conformational and dynamic properties of the stereoisomers of 4-methyl-5,6-benzo-2-oxo-1,3,2-dioxathiepin (5) and of the 4,7-dimethyl derivative (6) have been investigated by 1H and 13C dnmr methods, as well as by ir spectroscopy. Analysis of the nmr spectra at low temperature (−125 °C), together with the conformational interpretation of the stretching vibration bands of the S = O bond in the ir spectra, indicate that the most stable conformations detected for solutions in CHF2Cl are C-a (82%) and TB-t-Mec (18%) for 5a, TB-c-Mec, (96%) and TB-c-Mea, (4%) for 5b, C-a for 6a, TB-t-Mec, c-Mec, for 6b and C-e for 6c. The substituent effects of a methyl group at the benzylic position on both the conformational and dynamic properties of the seven-membered sulfite are discussed.