Adenovirus Type 5 Interactions with Human Blood Cells May Compromise Systemic Delivery

Abstract

Intravenous delivery of adenovirus vectors requires that the virus is not inactivated in the bloodstream. Serum neutralizing activity is well documented, but we show here that type 5 adenovirus also interacts with human blood cells. Over 90% of a typical virus dose binds to human (but not murine) erythrocytes ex vivo, and samples from a patient administered adenovirus in a clinical trial showed that over 98% of viral DNA in the blood was cell associated. In contrast, nearly all viral genomes in the murine bloodstream are free in the plasma. Adenovirus bound to human blood cells fails to infect A549 lung carcinoma cells, although dilution to below 1.7 x 10(7) blood cells/ml relieves this inhibition. Addition of blood cells can prevent infection by adenovirus that has been prebound to A549 cells. Adenovirus also associates with human neutrophils and monocytes ex vivo, particularly in the presence of autologous plasma, giving dose-dependent transgene expression in CD14-positive monocytes. Finally, although plasma with a high neutralizing titer (defined on A549 cells) inhibits monocyte infection, weakly neutralizing plasma can actually enhance monocyte transduction. This may increase antigen presentation following intravenous injection, while blood cell binding may both decrease access of the virus to extravascular targets and inhibit infection of cells to which the virus does gain access.

Factors influencing retention of adenovirus within tumours following direct intratumoural injection

“…Similarly DeWeese et al 17 and Tong et al 20 both used QPCR to measure viral genomes in the plasma of patients following IT injection of adenovirus, reporting the presence of 0.1 and 3.3% of the injected dose at 30 min, respectively. However, it is known that adenovirus in the human circulation is predominantly associated with blood cells rather than plasma, 4 and so both of these reports probably also underestimate the amount of adenovirus escaping from the tumour.…”

“…[1][2][3] Considerable resources are being deployed to enable systemic targeting of adenovirus from intravenous injection; however, promiscuous patterns of infection and poor blood compatibility 4 means that most therapeutic strategies currently require direct intratumoural (IT) injection. 5,6 The clinical trials of Onyx-015 that showed best responses involved direct IT injection of the virus, and the product licences granted in China for treatment of head and neck cancer using Gendicine (a non-replicating adenovirus expressing P53, marketed by SiBiono GeneTech) and H101 (based on Onyx-015 and marketed by Shanghai Sunway Biotech) both use IT delivery.…”

An ex vivo loop system models the toxicity and efficacy of PEGylated and unmodified adenovirus serotype 5 in whole human blood

“…17 This is probably a consequence of the fact that mouse erythrocytes lack CAR and CR1 whereas human erythrocytes express both receptors. 31 The infectivity of virus in human blood is dramatically decreased with time while mouse blood did not inhibit the infectivity of Ad5 in cell cultures.…”

“…16 The binding of antibodies together with activation of components of the innate immune system results in loss of viral infectivity after intravenous administration. 17 In mice it has been shown that adenoviruses induce a number of inflammatory cytokines, including TNF, IL-1b, IL-6, IL-12, IP-10 and MCP-1. 18 Furthermore, adenoviruses activate the complement system through the classical and alternative pathways.…”

Gene therapy targeting to tumor endothelium

“…23 Successful vectors must be able to survive in this harsh environment, ideally achieving extended plasma circulation kinetics in order to allow them to gain access to disseminated cancers. Unfortunately, following intravenous injection, most viral vectors are cleared very rapidly into the liver, predominantly via nonspecific phagocytosis by hepatic Kupffer cells.…”