-
[show abstract]
[hide abstract]
ABSTRACT: Adenovirus serotype 5 (Ad5) naturally infects the liver after intravenous injection making it a candidate for hepatocyte-directed gene transfer. While Ad5 can be efficient, most of the dose is destroyed by liver Kupffer cells before it can reach hepatocytes. In contrast, Ad5 bearing the hexon from Ad6 (Ad5/6) evades Kupffer cells. While Ad5/6 dramatically increases hepatocyte transduction in BALB/c mice, it surprisingly had little effect in C57BL/6 mice. To determine the source of this strain-specific variation, the roles of Kupffer cells, liver sinusoidal endothelial cells (LSECs), hepatocytes, scavenger receptors, clotting factors, and immunoglobulins were analyzed. Kupffer cell numbers and LSECs, clotting factor X, and hepatocyte infectability did not vary between different strains of mice. In contrast, high levels of immunoglobulins correlated negatively with Ad5 liver transduction in different mouse strains. Removal of immunoglobulins by use of Rag-deficient mice restored Ad5 transduction to maximal levels. Removal of Kupffer cells by predosing or by testing in colony-stimulating factor knock-out mice restored Ad5 transduction in the presence of immunoglobulins. Partial reconstitution of IgM in Rag mice resulted in significant reduction in liver transduction by Ad5, but not Ad5/6. These data suggest a role for IgM-mediated clearance of Ad5 via Kupffer cells and evasion of this clearance mechanism by Ad5/6. These mechanisms may play a vital role in Ad pharmacology in animals and in humans.
Journal of Virology 01/2013; · 5.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Optical imaging of luciferage gene expression has become a powerful tool to track cells and viruses in vivo in small animal models. Luciferase imaging has been used to study the location of infection by replication-defective and replication-competent viruses and to track changes in the distribution of viruses in mouse models. This approach has also been used in oncolytic studies as a noninvasive means to monitor the growth and killing of tumor cells modified with luciferase genes. In this chapter, we describe the techniques used for luciferase imaging as have been applied to track replication-defective and replication-competent adenoviruses in mouse and hamster models of oncolysis and virus pharmacology. Although these methods are simple, the process of obtaining accurate luciferase imaging data has many caveats that are discussed.
Methods in molecular biology (Clifton, N.J.) 01/2012; 797:79-87.
-
[show abstract]
[hide abstract]
ABSTRACT: Most of an intravenous dose of species C adenovirus serotype 5 (Ad5) is destroyed by liver Kupffer cells. In contrast, another species C virus, Ad6, evades these cells to mediate more efficient liver gene delivery. Given that this difference in Kupffer cell interaction is mediated by the hypervariable (HVR) loops of the virus hexon protein, we genetically modified each of the seven HVRs of Ad5 with a cysteine residue to enable conditional blocking of these sites with polyethylene glycol (PEG). We show that these modifications do not affect in vitro virus transduction. In contrast, after intravenous injection, targeted PEGylation at HVRs 1, 2, 5, and 7 increased viral liver transduction up to 20-fold. Elimination or saturation of liver Kupffer cells did not significantly affect this increase in the liver transduction. In vitro, PEGylation blocked uptake of viruses via the Kupffer cell scavenger receptor SRA-II. These data suggest that HVRs 1, 2, 5, and 7 of Ad5 may be involved in Kupffer cell recognition and subsequent destruction. These data also demonstrate that this conditional genetic-chemical mutation strategy is a useful tool for investigating the interactions of viruses with host tissues.
Journal of Virology 12/2011; 86(4):2293-301. · 5.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Oncolytic viruses are self-amplifying anticancer agents that make use of the natural ability of viruses to kill cells. Adenovirus serotype 5 (Ad5) has been extensively tested against solid cancers, but less so against B-cell cancers because these cells do not generally express the coxsackie and adenoviral receptor (CAR). To determine whether other adenoviruses might have better potency, we "mined" the adenovirus virome of 55 serotypes for viruses that could kill B-cell cancers.
Fifteen adenoviruses selected to represent Ad species B, C, D, E, and F were tested in vitro against cell lines and primary patient B-cell cancers for their ability to infect, replicate in, and kill these cells. Select viruses were also tested against B-cell cancer xenografts in immunodeficient mice.
Species D adenoviruses mediated most robust killing against a range of B-cell cancer cell lines, against primary patient marginal zone lymphoma cells, and against primary patient CD138+ myeloma cells in vitro. When injected into xenografts in vivo, single treatment with select species D viruses Ad26 and Ad45 delayed lymphoma growth.
Relatively unstudied species D adenoviruses have a unique ability to infect and replicate in B-cell cancers as compared with other adenovirus species. These data suggest these viruses have unique biology in B cells and support translation of novel species D adenoviruses as oncolytics against B-cell cancers.
Clinical Cancer Research 09/2011; 17(21):6712-22. · 7.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have screened human adenoviruses (Ads) for oncolytic activity against a variety of mouse and hamster cell lines and have found a number that are susceptible to a variety of Ad serotypes. A20 lymphoma is derived from BALB/c mice and is susceptible to infection and killing by a variety of human Ads. A20 is also a suitable cancer vaccine model, because these cells express a unique immunoglobulin variable region that can be targeted by vaccination. To compare Ads as cancer vaccines versus Ads as oncolytics, A20 tumors were initiated in immunocompetent BALB/c mice. Mice immunized with first-generation Ad5 expressing the A20 immunoglobulin ScFv immunogen (Ad-A20) were protected against A20 lymphomas only when the vaccine was delivered before tumor. In contrast, vaccination after tumor initiation failed to increase survival or delay tumor growth. When Ad serotypes from species B, C, D, and E were tested as oncolytics in vitro, A20 cells were most efficiently killed by species D Ads, with intermediate activity by species B Ads. When tested in vivo in immunocompetent BALB/c mice bearing A20 tumors, single intratumoral injection of species D Ad26 and Ad48 were effective at controlling tumor growth. These data demonstrate that in this immunocompetent mouse cancer model, the oncolytic activity of adenoviruses is more potent than their use as a cancer vaccine. These data in immunocompetent mice lend further support to species D Ads as promising oncolytic viruses against B cell cancers.
Human gene therapy 07/2011; 22(9):1095-100. · 4.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Adenoviruses (Ads) are arguably one of the most potent viruses for in vivo gene therapy, vaccine, and oncolytic applications. The attraction for the use of Ads stems from their ability to infect a wide range of dividing and non-dividing cell types in some cases to efficiencies of nearly 100%. Additional benefits include their stability, the ability to purify the vector to concentrations of up to 1013 particles/ml, and the fact that viral vectors self-assemble into particles of specific size (∼100 nm). The vast majority of clinical applications of Ad have utilized Ad serotype 5 (Ad5) viruses. Considering that at least half of humans are already immune to Ad5, Ad5 oncolytics may not be optimal for clinical translation. Given this and that there are 54 different serotypes of human Ads, this review considers the utility of "mining" these alternate Ad serotypes for viruses that can evade Ad5 immunity and kill different types of cancer.
Current pharmaceutical biotechnology 07/2011; 13(9):1804-8. · 3.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: As much as 90% of an intravenously (i.v.) injected dose of adenovirus serotype 5 (Ad5) is absorbed and destroyed by liver Kupffer cells. Viruses that escape these cells can then transduce hepatocytes after binding factor X (FX). Given that interactions with FX and Kupffer cells are thought to occur on the Ad5 hexon protein, we replaced its exposed hypervariable regions (HVR) with those from Ad6. When tested in vivo in BALB/c mice and in hamsters, the Ad5/6 chimera mediated >10 times higher transduction in the liver. This effect was not due to changes in FX binding. Rather, Ad5/6 appeared to escape Kupffer cell uptake as evidenced by producing no Kupffer cell death in vivo, not requiring predosing in vivo, and being phagocytosed less efficiently by macrophages in vitro compared to Ad5. When tested as a helper-dependent adenovirus (Ad) vector, Ad5/6 mediated higher luciferase and factor IX transgene expression than either helper-dependent adenoviral 5 (HD-Ad5) or HD-Ad6 vectors. These data suggest that the Ad5/6 hexon-chimera evades Kupffer cells and may have utility for systemic and liver-directed therapies.
Molecular Therapy 04/2011; 19(7):1254-62. · 6.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Adenovirus is a robust vector for therapeutic applications, but its use is limited by our understanding of its complex in vivo pharmacology. In this review we describe the necessity of identifying its natural, widespread, and multifaceted interactions with the host since this information will be crucial for efficiently redirecting virus into target cells. In the rational design of vectors, the notion of overcoming a sequence of viral "sinks" must be combined with re-targeting to target populations with capsid as well as shielding the vectors from pre-existing or toxic immune responses. It must also be noted that most known adenoviral pharmacology is deduced from the most commonly used serotypes, Ad5 and Ad2. However, these serotypes may not represent all adenoviruses, and may not even represent the most useful vectors for all purposes. Chimeras between Ad serotypes may become useful in engineering vectors that can selectively evade substantial viral traps, such as Kupffer cells, while retaining the robust qualities of Ad5. Similarly, vectorizing other Ad serotypes may become useful in avoiding immunity against Ad5 altogether. Taken together, this research on basic adenovirus biology will be necessary in developing vectors that interact more strategically with the host for the most optimal therapeutic effect.
Current Gene Therapy 04/2011; 11(4):241-58. · 3.39 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Adenovirus serotype (Ad5) is the most studied Ad. Ad1, 2, and 6 are also members of species C Ad and are presumed to have biologies similar to Ad5. In this work, we have compared the ability of Ad1, 2, 5, and 6 to infect liver and muscle after intravenous and intramuscular injection. We found that Ad6 was surprisingly the most potent at liver gene delivery and that Ad1 and Ad2 were markedly weaker than Ad5 and 6. To understand these differences, we sequenced the Ad6 genome. This revealed that the Ad6 fiber protein is surprisingly three shaft repeats shorter than the others which may explain differences in virus infectivity in vitro, but not in the liver. Comparison of hexon hypervariable regions (HVRs) suggests that the higher transduction by Ad5 and 6 as compared to Ad1 and 2 may be related to differences in charge and length.
Virology 01/2011; 412(1):19-27. · 3.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The distribution of viruses and gene therapy vectors is difficult to assess in a living organism. For instance, trafficking in murine models can usually only be assessed after sacrificing the animal for tissue sectioning or extraction. These assays are laborious requiring whole animal sectioning to ascertain tissue localization. They also obviate the ability to perform longitudinal or kinetic studies in one animal. To track viruses after systemic infection, we have labeled adenoviruses with a near-infrared (NIR) fluorophore and imaged these after intravenous injection in mice. Imaging was able to track and quantitate virus particles entering the jugular vein simultaneous with injection, appearing in the heart within 500 milliseconds, distributing in the bloodstream and throughout the animal within 7 seconds, and that the bulk of virus distribution was essentially complete within 3 minutes. These data provide the first in vivo real-time tracking of the rapid initial events of systemic virus infection.
PLoS ONE 01/2011; 6(2):e17076. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Influenza poses a persistent worldwide threat to the human population. As evidenced by the 2009 H1N1 pandemic, current vaccine technologies are unable to respond rapidly to this constantly diverging pathogen. We tested the utility of adenovirus (Ad) vaccines expressing centralized consensus influenza antigens. Ad vaccines were produced within 2 months and protected against influenza in mice within 3 days of vaccination. Ad vaccines were able to protect at doses as low as 10(7) virus particles/kg indicating that approximately 1,000 human doses could be rapidly generated from standard Ad preparations. To generate broadly cross-reactive immune responses, centralized consensus antigens were constructed against H1 influenza and against H1 through H5 influenza. Twenty full-length H1 HA sequences representing the main branches of the H1 HA phylogenetic tree were used to create a synthetic centralized gene, HA1-con. HA1-con minimizes the degree of sequence dissimilarity between the vaccine and existing circulating viruses. The centralized H1 gene, HA1-con, induced stronger immune responses and better protection against mismatched virus challenges as compared to two wildtype H1 genes. HA1-con protected against three genetically diverse lethal influenza challenges. When mice were challenged with 1934 influenza A/PR/8/34, HA1-con protected 100% of mice while vaccine generated from 2009 A/TX/05/09 only protected 40%. Vaccination with 1934 A/PR/8/34 and 2009 A/TX/05/09 protected 60% and 20% against 1947 influenza A/FM/1/47, respectively, whereas 80% of mice vaccinated with HA1-con were protected. Notably, 80% of mice challenged with 2009 swine flu isolate A/California/4/09 were protected by HA1-con vaccination. These data show that HA1-con in Ad has potential as a rapid and universal vaccine for H1N1 influenza viruses.
PLoS ONE 01/2011; 6(3):e18314. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Propionic acidemia (PA) is an autosomal recessive disorder of metabolism caused by a deficiency of propionyl-coenzyme A carboxylase (PCC). Despite optimal dietary and cofactor therapy, PA patients still suffer from lethal metabolic instability and experience multisystemic complications. A murine model of PA (Pcca(-/-)) of animals that uniformly die within the first 48 hr of life was used to determine the efficacy of adeno-associated viral (AAV) gene transfer as a potential therapy for PA. An AAV serotype 8 (AAV8) vector was engineered to express the human PCCA cDNA and delivered to newborn mice via an intrahepatic injection. Greater than 64% of the Pcca(-/-) mice were rescued after AAV8-mediated gene transfer and survived until day of life 16 or beyond. Western analysis of liver extracts showed that PCC was completely absent from Pcca(-/-) mice but was restored to greater than wild-type levels after AAV gene therapy. The treated Pcca(-/-) mice also exhibited markedly reduced plasma levels of 2-methylcitrate compared with the untreated Pcca(-/-) mice, which indicates significant PCC enzymatic activity was provided by gene transfer. At the time of this report, the oldest treated Pcca(-/-) mice are over 6 months of age. In summary, AAV gene delivery of PCCA effectively rescues Pcca(-/-) mice from neonatal lethality and substantially ameliorates metabolic markers of the disease. These experiments demonstrate a gene transfer approach using AAV8 that might be used as a treatment for PA, a devastating and often lethal disorder desperately in need of new therapeutic options.
Human gene therapy 10/2010; 22(4):477-81. · 4.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Abstract It has been shown that blood clotting factors, including factor X (FX), bind to the adenovirus serotype 5 (Ad5) hexon protein and target the virus to liver hepatocytes after intravenous injection. These factors bind to hexon via their conserved vitamin K-dependent gamma-carboxyglutamic acid (GLA) domains with subnanomolar affinity. In this work, we have used this strong interaction to retarget Ad to new receptors, using the GLA domain of FX fused to single-chain antibody variable fragment (ScFv). We demonstrate that fusion of the GLA domain of human FX to receptor-specific ScFvs will target Ad5 vectors to cells expressing these receptors. Fusion of an alphaHer2 ScFv to GLA increased in vitro transduction of Her2-positive versus Her2-negative cells when compared with untargeted virus. Similar results were obtained with ScFvs against the epidermal growth factor receptor (EGFR) and against the stem cell marker ATP-binding cassette protein G2 (ABCG2). Direct expression of GLA fusion protein from replication-defective or replication-competent Ad increased infection and killing of cancer cells in vitro and in vivo. These data demonstrate the potential of using GLA domains to bridge secreted ligands with intracellularly produced Ad5 vectors for vector targeting.
Human gene therapy 03/2010; 21(6):739-49. · 4.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Adenoviral gene therapy vectors have been widely studied and used. Their extremely high transduction efficiency and gene delivery in vivo make them attractive for cancer gene therapy approaches. While they are robust, they are also very immunogenic. One approach to mitigate the immunogenicity of adenoviruses and to evade neutralizing antibodies is to coat the virus with the hydrophilic polymer polyethylene glycol (PEG) (1). This chapter details the steps involved when going from recombinant adenoviral vector plasmid all the way to validated PEGylated adenovirus product.
Methods in molecular biology (Clifton, N.J.) 01/2010; 651:227-39.
-
[show abstract]
[hide abstract]
ABSTRACT: Groups of rhesus macaques that had previously been immunized with HIV-1 envelope (env) peptides and first generation adenovirus serotype 5 (FG-Ad5) vaccines expressing the same peptides were immunized intramuscularly three times with helper-dependent adenovirus (HD-Ad) vaccines expressing only the HIV-1 envelope from JRFL. No gag, pol, or other SHIV genes were used for vaccination. One group of the FG-Ad5-immune animals was immunized three times with HD-Ad5 expressing env. One group was immunized by serotype-switching with HD-Ad6, HD-Ad1, and HD-Ad2 expressing env. Previous work demonstrated that serum antibody levels against env were significantly higher in the serotype-switched group than in the HD-Ad5 group. In this study, neutralizing antibody and T cell responses were compared between the groups before and after rectal challenge with CCR5-tropic SHIV-SF162P3. When serum samples were assayed for neutralizing antibodies, only weak activity was observed. T cell responses against env epitopes were higher in the serotype-switched group. When these animals were challenged rectally with SHIV-SF162P3, both the Ad5 and serotype-switch groups significantly reduced peak viral loads 2 to 10-fold 2 weeks after infection. Peak viral loads were significantly lower for the serotype-switched group as compared to the HD-Ad5-immunized group. Viral loads declined over 18 weeks after infection with some animals viremia reducing nearly 4 logs from the peak. These data demonstrate significant mucosal vaccine effects after immunization with only env antigens. These data also demonstrate HD-Ad vectors are a robust platform for vaccination.
Viruses 12/2009; 1(3):920. · 1.50 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The treatment of certain diseases will require the systemic delivery of therapeutic genes or viruses. In most cases, intravascular injection is the best delivery method to achieve the systemic distribution of viruses and to enable these agents to reach distant therapeutic sites. However, viruses administered by intravascular injection encounter overlapping barriers that impede their ability to reach their targets, including interactions with blood cells, blood factors and endothelial cells, loss to hepatocytes and macrophages, and destruction by innate and adaptive immune responses. In this review, recent advances in the understanding of the mechanisms determining virus tropism following systemic administration and the pharmacology of therapeutic viruses are described. Adenoviruses are used as a paradigm of these interactions, and factors affecting their therapeutic efficacy and side effects are discussed, as well as how the barriers that impede their ability to reach their targets translate to other therapeutic viruses.
Current opinion in molecular therapeutics 09/2009; 11(4):411-20. · 3.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: One of the significant hurdles toward safe and efficacious systemic treatment of cancer with oncolytic adenoviruses (Ads) is dose-limiting hepatotoxicity that prevents the increase of a therapeutic dose. In this study, we expanded the therapeutic window of oncolytic serotype 5 Ad (Ad5) by a genetic modification of hypervariable loop 5 (HVR5) in the capsid protein hexon that prevented infection of hepatocytes due to ablation of binding to blood factors. This oncolytic virus, Ad-GL-HB, had significantly reduced levels of hepatocyte transduction in immunocompetent and immunodeficient mice as compared to parental virus Ad-GL. The hepatocyte detargeting decreased liver damage and increased the maximum tolerated dose of Ad-GL-HB tenfold relative to that of Ad-GL. Intravenous (i.v.) injection of Ad-GL or Ad-GL-HB into tumor-bearing mice produced equally increased survival rates demonstrating that while Ad-GL-HB detargeted hepatocytes, it sustained tumor cell infection after systemic administration. The significantly improved safety of the virus allowed it to be used at increased doses for improved systemic antitumor efficacy. Our results suggest that hexon modifications provide valuable strategies for systemic oncolytic Ad therapy.
Molecular Therapy 09/2009; 17(12):2121-30. · 6.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Oncolytic virotherapy makes use of the natural ability of viruses to infect and kill cancer cells. Adenovirus serotype 5 (Ad5) has been approved for use in humans as a therapy for solid cancers. In this study, we have tested whether Ad5 and low-seroprevalence adenoviruses can be used as oncolytics for multiple myeloma (MM). We show that Ad5 productively infects most myeloma cell lines, replicates to various degrees, and mediates oncolytic cell killing in vitro and in vivo. Comparison of Ad5 with low-seroprevalence Ads on primary marrow samples from MM patients revealed striking differences in the abilities of different adenoviral serotypes to kill normal CD138(-) cells and CD138(+) MM cells. Ad5 and Ad6 from species C and Ad26 and Ad48 from species D all mediated killing of CD138(+) cells with low-level killing of CD138(-) cells. In contrast, Ad11, Ad35, Ad40, and Ad41 mediated weak oncolytic effects in all of the cells. Comparison of cell binding, cell entry, and replication revealed that Ad11 and Ad35 bound MM cells 10 to 100 times better than other serotypes. However, after this efficient interaction, Ad11 and Ad35 viral DNA was not replicated and cell killing did not occur. In contrast, Ad5, Ad6, Ad26, and Ad48 all replicated 10- to 100-fold in MM cells and this correlated with cell killing. These data suggest that Ad5 and other low-seroprevalence adenoviruses may have utility as oncolytic agents against MM and other hematologic malignancies.
Human gene therapy 09/2009; 21(2):179-90. · 4.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Oncolytic adenoviruses are anticancer agents that replicate within tumors and spread to uninfected tumor cells, amplifying the anticancer effect of initial transduction. We tested whether coating the viral particle with polyethylene glycol (PEG) could reduce transduction of hepatocytes and hepatotoxicity after systemic (intravenous) administration of oncolytic adenovirus serotype 5 (Ad5). Conjugating Ad5 with high molecular weight 20-kDa PEG but not with 5-kDa PEG reduced hepatocyte transduction and hepatotoxicity after intravenous injection. PEGylation with 20-kDa PEG was as efficient at detargeting adenovirus from Kupffer cells and hepatocytes as virus predosing and warfarin. Bioluminescence imaging of virus distribution in two xenograft tumor models in nude mice demonstrated that PEGylation with 20-kDa PEG reduced liver infection 19- to 90-fold. Tumor transduction levels were similar for vectors PEGylated with 20-kDa PEG and unPEGylated vectors. Anticancer efficacy after a single intravenous injection was retained at the level of unmodified vector in large established prostate carcinoma xenografts, resulting in complete elimination of tumors in all animals and long-term tumor-free survival. Anticancer efficacy after a single intravenous injection was increased in large established hepatocellular carcinoma xenografts, resulting in significant prolongation of survival as compared with unmodified vector. The increase in efficacy was comparable to that obtained with predosing and warfarin pretreatment, significantly extending the median of survival. Shielding adenovirus with 20-kDa PEG may be a useful approach to improve the therapeutic window of oncolytic adenovirus after systemic delivery to primary and metastatic tumor sites.
Human gene therapy 06/2009; 20(9):975-88. · 4.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Understanding innate immunity is key to improving the safety of adenovirus (Ad) vectors for systemic gene therapy. Ad has been shown to activate complement in vitro, but activation of complement after Ad injection in vivo has not been directly measured. Using complement protein C3a as a marker of complement activation, we show that types 2 and 5 human Ads cause rapid complement activation after intravenous injection in mice. Unexpectedly, the mechanisms in vivo were different than those in vitro. Antibodies were critical for the activation of complement by Ad in vitro, but antibodies were not required in vivo. The classical pathway was required in vitro, whereas complement activation in vivo involved both classical and nonclassical pathways as well as the reticuloendothelial system. Remarkably, the entry-deficient Ad mutant ts1 was completely unable to activate complement in vivo even though it was fully able to activate complement in vitro. This result demonstrates that the complement system senses intravenously injected Ad primarily by detecting the effects of Ad on cells rather than through direct interaction of complement with virions. Encouragingly, shielding Ad with polyethylene glycol was effective at reducing complement activation both in vitro and in vivo. In summary, intravenously injected Ad rapidly activates complement through multiple pathways, but these pathways are different than those identified by in vitro studies. In vitro studies are poorly predictive of in vivo mechanisms because Ad virions activate complement through indirect mechanisms in vivo.
Journal of Virology 04/2009; 83(11):5648-58. · 5.40 Impact Factor
