One disadvantage of vesicular stomatitis virus G (VSV-G

Recombinant adenovirus (Ad) serotype 5 is a vector commonly used for gene delivery. Although this vector has a natural tropism for the liver, there is a limited understanding of how Ad administration affects one of the primary hepatic processes, drug metabolism. The effects of systemic administration of a model recombinant adenoviral vector on two hepatic cytochrome P450 (P450) enzymes, CYP3A2 and 2C11, were investigated. Sprague-Dawley rats were treated with one of six vector doses, ranging from 5.7 ϫ 10 6 to 5.7 ϫ 10 12 virus particles (vp)/kg. Hepatic P450 protein expression, catalytic activity, and mRNA levels were measured over 14 days. Ad administration (5.7 ϫ 10 10 -5.7 ϫ 10 12 vp/kg) reduced CYP3A2 over the duration of the study. Six hours after administration of 5.7 ϫ 10 12 vp/kg, CYP3A2 activity and mRNA levels were suppressed by 45 and 65%, respectively (P Յ 0.01). This continued throughout the study with levels dropping to 36 and 45% of controls by 14 days, respectively (P Յ 0.01). A similar trend was detected for CYP2C11 within this dosing range. Administration of 5.7 ϫ 10 6 , 5.7 ϫ 10 8 , and 5.7 ϫ 10 9 vp/kg of Ad significantly increased both CYP2C11 protein expression by 86, 71, and 107% and activity 110, 118, and 53%, respectively, above those of animals treated with saline (P Յ 0.01). These results clearly indicate that a single dose of adenovirus significantly alters key drug metabolizing enzymes for an extended period of time and should be investigated further in the context of the design and implementation of clinical trial protocols.

The immunogenic and biological nature of the transgene cassette can influence changes in CYP3A2, but not the 2C11 isoform. The shift in transcription and translation of protein for maintenance of physiologic homeostasis to production of viral proteins and transgene product and their associated toxicity during viral infection may explain our observations.

In this report we test the hypothesis that long-term virus-induced alterations in CYP occur from changes initiated by the virus that may not be related to the immune response. Enzyme activity, protein expression and mRNA of CYP3A2, a correlate of human CYP3A4, and CYP2C11, responsive to inflammatory mediators, were assessed 0.25, 1, 4, and 14 days after administration of several different recombinant adenoviruses at a dose of 5.7 × 10 12 virus particles (vp)/kg to male Sprague Dawley rats. Wild type adenovirus, containing all viral genes, suppressed CYP3A2 and 2C11 activity by 37% and 39%, respectively within six hours. Levels fell to 67% (CYP3A2) and 79% (CYP2C11) of control by 14 days (p ≤ 0.01). Helper-dependent adenovirus, with all viral genes removed, suppressed CYP3A2 (43%) and CYP2C11 (55%) within six hours. CYP3A2 remained significantly suppressed (47%, 14 days, p ≤ 0.01) while CYP2C11 returned to baseline at this time. CYP3A2 and 2C11 were reduced by 45 and 42% respectively 6 hours after treatment with PEGylated adenovirus, which has a low immunological profile (p ≤ 0.05). CYP3A2 remained suppressed (34%, p ≤ 0.05) for 14 days while CYP2C11 recovered. Inactivated virus suppressed CYP3A2 activity by 25-50% for 14 days (p ≤ 0.05). CYP2C11 was affected similar manner but recovered by day 14. Microarray and in vitro studies suggest that changes in cellular signaling pathways initiated early in virus infection contribute to changes in CYP.

Inactivated viruses are important tools for vaccine development and gene transfer. 8-methoxypsoralen (8-MOP) and long-wavelength ultraviolet irradiation (LWUVI) inactivates many viruses. Toxicity limits its use in animals and humans. Toxicological and photosensitizing properties of riboflavin make it suitable for virus inactivation in preparations for biological use. Viruses expressing beta-galactosidase were mixed with either 8-MOP (1.5 mM) or riboflavin (50 μM) and exposed to LWUVI (365 nm) for 2 hours. Virus activity was determined by limiting dilution. The half-life of the adenovirus preparation treated with 8-MOP was 8.28 nanoseconds −1 (ns −1 ) and 36.5 ns −1 after treatment with riboflavin. Despite the difference in half-life, both preparations were completely inactivated within 45 minutes. In contrast, the half-lives for adeno-associated virus (AAV) preparations were similar (63 ns −1 8-MOP vs. 67 ns −1 riboflavin). Each AAV preparation was fully inactivated within 90 minutes. The half-life of lentivirus was 193.4 ns −1 after treatment with 8-MOP and 208 ns −1 after exposure to riboflavin. Virus treated with riboflavin was inactivated within 20 minutes. Virus exposed to 8-MOP was inactivated in 90 minutes. DNA and RNA viruses can be inactivated by riboflavin and LWUVI and used in physiological systems sensitive to other photochemicals.