Browsing by Subject "Adenovirus"
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Item Human adenovirus serotype 5 vaccines : routes of delivery and formulations for successful immunization(2010-08) Dekker, Joseph Dylan; Tucker, Philip W.; Kobinger, Gary P.; Otto, Glen; Sullivan, Christopher S.; Huibregtse, Jon M.Delivery of medicinal products to specific targets can be aided by utilizing different routes of administration. Particular routes may be advantageous when delivering products designed for therapeutic drug delivery, gene therapy, or vaccination. Vaccine candidates must remain stable, be delivered to their proper compartments, and promote sufficient immune responses to their delivered antigens, properties that can be modulated by formulation, adjuvants, and alternate routes of administration. Recently, the nasal passageway has been recognized as a promising route, as mucosally delivered vaccines have the advantage of inducing protection at both mucosal surfaces, a common site of infection, and systemically. Human adenovirus serotype 5 (Ad5) is a candidate vaccine vector capable of being delivered through several routes and inducing strong immune responses to its delivered transgene. The studies presented include vaccination strategies following different routes of administration with various formulation components to determine the ability of Ad5 to deliver its transgene and induce immune responses. The first study screens formulation candidates’ effects on an Ad5-based vaccine’s transduction in vitro, cellular and humoral immune responses in vivo, and efficacy upon challenge in mice. Screening formulation candidates in vitro can eliminate ineffective formulations, thereby limiting animal testing. An Ad5-based Ebola virus vaccine delivered in a combination of mannitol, sucrose, and the surfactant, pluronic F68, improves survival against lethal Ebola challenge in a mouse model compared to delivery in PBS alone. The second study tests the effect of an intravenously delivered Ad5-based vaccine complexed with anti-Ad5 neutralizing antibodies on cellular and humoral immune responses. Different antibody ratios complexed to the Ad5 vector are able to induce disparate cellular and humoral responses. Ratios initiating a strong humoral response towards the Ad5 vector correlate with a reduction of the humoral response against the transgene and few transgene targeted effector T cells. Accordingly, ratios leading to minor humoral responses to the Ad5 vector resulted in stronger humoral responses to the transgene and a strong effector memory T cell response. Taken together, these studies provide insight on how to achieve necessary immune responses in vaccine protocols by testing routes of administration, formulations, and surface modifications of the Ad5 vector.Item A mechanistic study of how adenovirus infection alters the expression and function of hepatic cytochrome P450 3A(2010-08) Wonganan, Piyanuch; Croyle, Maria A.; Ghose, Romi; McConville, Jason T.; Van Den Berg, Carla L.; Whitman, Chirstian P.Recombinant adenoviruses, commonly used in gene therapy and vaccine applications, compromise the expression and function of hepatic CYP3A for 14 days. When given with docetaxel (DTX), plasma clearance of DTX (3.38 ± 0.22 l/kg.h) was significantly lower than those given DTX alone (6.41 ± 1.10 l/kg.h). The area under the plasma concentration-time curve of DTX in rats given virus (2,987.37 ± 197.97 ng/ml.h) was significantly greater than those given drug alone (1,666.59 ± 317.04 ng/ml.h). The virus extended the half-life of DTX three-fold. This may explain why adenoviral vectors improve chemotherapy. PEGylation of the virus reduced interleukin-6 (IL-6), IL-12, tumor necrosis factor alpha (TNF-α), aspartate transaminase (AST) and lactate dehydrogenase (LDH) levels in mice and non-human primates. PEGylation dramatically reduced transduction efficiency of virus in the baboon liver and did not alter hepatic transgene expression in the mouse. Unmodified and PEGylated virus (3 x 1012 vp/kg) reduced hepatic CYP3A4 protein by 60% and 40%, respectively 96 hours after virus administration. Catalytic activity was decreased by 55% and 45% with respect to an untreated control by the native and PEGylated viruses respectively. This suggests that changes in hepatic CYP3A during infection is not entirely due to the immune response and these observed effects most likely occur in humans. The effects of adenovirus on hepatic CYP3A expression and function in mice, however, resolved at a faster rate than that in baboons. HC-04 cells are a suitable in vitro model to study virus infection and hepatic CYP3A function. A panel of adenoviruses inhibited CYP3A catalytic activity and induced changes in expression and distribution of retinoid X receptor alpha (RXRα), pregnane X receptor (PXR) and constitutive androstane (CAR) receptors. Virus (1.5 x 1011 vp) inhibited CYP3A in the mouse. When the ability of the virus to bind to integrins was removed, changes in CYP were not detected. Treatment with a RGD peptide, that binds to integrins, reduced CYP3A activity in a manner similar to the virus. Silencing of β3 and β5 integrins also resolved changes in CYP3A activity during infection, suggesting that simple engagement of integrin receptors can initiate changes in CYP3A.Item Optimization of poly (D-L-lactide-co-glycolide) microsphere production for oral delivery to promote adenovirus stability and intestinal gene transfer(2007-05) Boquet, Michael Paul; McGinity, James W.Adenovirus vectors have demonstrated many of the characteristics necessary to be successfully used as a carrier in a vaccine delivery system. Adenovirus is a good choice for a vaccine carrier because it generates vigorous T and B cell responses to its transgene products. Although current vaccination strategies using this vector have had some success, its use has been constrained by the presence of pre-existing immunity to human serotypes in about 50% of the population. Recently, it has been demonstrated that the induction of these adenovirus-specific neutralizing antibodies that reduce efficacy of initial treatment and booster immunizations does not apply to oral delivery. Adenovirus is a good candidate for oral vaccine delivery because it is capable of inducing antibody responses against an encoded transgene product at mucosal surfaces, which may result in complete systemic and mucosal immunity. Nevertheless, there are some limitations associated with the oral delivery of protein, peptide, and virus-based vaccines. Virus-based vaccines are sensitive to the low pH and presence of proteases in the gut limiting their activity and cellular uptake is also hindered by the rapid transit time of compounds through the intestine. In general, there are two primary strategies for enhancing mucosal immunity: mucosal adjuvants and encapsulation in microparticles. Although several groups have successfully encapsulated adenovirus in polymeric formulations, it has been found that the encapsulation process drastically reduces viral function. However, the best performance has been reported with formulations containing poly(lactide-co-glycolide) (PLGA). Thus, the primary objective of this study was to optimize the encapsulation process of a recombinant adenovirus vector in PLGA microspheres to maximize virus stability and promote intestinal gene transfer. Production parameters were systematically adjusted to find the best formulation for virus release and stability. Optimization of the production process increased viral release from 7 to 15 days and resulted in a 200-fold increase in the total number of infectious virus particles released compared to the original formulation.