Novel Replication-Incompetent Vector Derived from Adenovirus Type 11 (Ad11) for Vaccination and Gene Therapy: Low Seroprevalence and Non-Cross-Reactivity with Ad5

Abstract

A novel plasmid-based adenovirus vector system that enables manufacturing of replication-incompetent (⌬E1) adenovirus type 11 (Ad11)-based vectors is described. Ad11 vectors are produced on PER.C6/55K cells yielding high-titer vector batches after purification. Ad11 seroprevalence proves to be significantly lower than that of Ad5, and neutralizing antibody titers against Ad11 are low. Ad11 seroprevalence among human immunodeficiency virus-positive (HIV ؉ ) individuals is as low as that among HIV ؊ individuals, independent of the level of immune suppression. The low level of coinciding seroprevalence between Ad11 and Ad35 in addition to a lack of correlation between high neutralizing antibody titers towards either adenovirus strongly suggest that the limited humoral cross-reactive immunity between these two highly related B viruses appears not to preclude the use of both vectors in the same individual. Ad11 transduces primary cells including smooth muscle cells, synoviocytes, and dendritic cells and cardiovascular tissues with higher efficiency than Ad5. Ad11 and Ad35 appear to have a similar tropism as judged by green fluorescent protein expression levels determined by using a panel of cancer cell lines. In addition, Ad5 preimmunization did not significantly affect Ad11-mediated transduction in C57BL/6 mice. We therefore conclude that the Ad11-based vector represents a novel and useful candidate gene transfer vehicle for vaccination and gene therapy.Adenovirus vectors are being developed for gene therapy purposes with the aim to treat inherited or acquired disease (6, 10, 15, 21) as well as for therapeutic and prophylactic vaccination strategies (5, 32). The use of adenovirus for vaccination has recently been fueled by highly promising results demonstrating protection against viruses and viral diseases in rodents and nonhuman primates (28,34,35) as well as induction of Tand B-cell responses in humans in early phase I vaccine trials with healthy volunteers (7). However, high seroprevalence and high neutralizing antibody (NAb) titers against the commonly used vectors, i.e., adenovirus type 5 (Ad5) and Ad2 (39), hamper the application of C group-based vectors, since circulating NAbs efficiently capture administered recombinant vectors obscuring therapeutic effect (19). It has been shown, at least in rodents (1, 42), nonhuman primates (3), and humans in early phase I clinical trials (7), that high levels of NAbs decrease gene transfer efficiency or blunt vaccine potency. Since levels of NAbs vary among individuals, overdosing with recombinant vector in an attempt to overcome the neutralizing activity may result in either excellent clinical results or severe vector-mediated toxicity. Thus, the presence of anti-Ad5 preexisting immunity does not allow accurate dose control and thereby may prevent the universal use of Ad5-based vectors as gene transfer vehicles in humans.Although many strategies are being pursued to avoid vector neutralization (3,5,19,23,41,43), a most viable strategy is the use of rare human adenovirus...

Wild-type adenoviruses from groups A–F evoke unique innate immune responses, of which HAd3 and SAd23 are partially complement dependent

“…26,27 Furthermore, the incidence rate of seroconversion to many alternative serotype HAds in many cases are significantly lower than the seroconversion rates noted for HAd5. 28 These facts have justified multiple investigations into the use of alternative serotype Ads for potential use in numerous human gene transfer applications. 29 However, it is also likely that using alternative serotype Ads may also generate unanticipated biological consequences.…”

Downregulation of human CD46 by adenovirus serotype 35 vectors

“…First, Ad11 and Ad35 are known to be rarely neutralized by human sera. 18 Second, Ad11 and Ad35 exhibit a broad tropism including cells expressing no or low levels of coxsackievirus and adenovirus receptor (CAR), which is a receptor for Ads belonging to subgroups A, C, D, E and F. 19 Several groups (including the authors) have developed replication-incompetent Ad vectors composed of subgroup B Ads [20][21][22][23][24] or fibersubstituted Ad serotype 5 (Ad5) vectors containing subgroup B Ad fibers, [25][26][27][28] and have demonstrated that these types of Ad vectors efficiently transduce a variety of human cells, including cells refractory to conventional Ad5 vectors. If surface CD46 downregulation occurs following transduction with CD46-utilizing Ad vectors, unexpected side effects might occur such as complementmediated cell lysis of successfully transduced cells, which leads to clearance of the transduced cells.…”

Adenovirus serotype 35 vector-mediated transduction into human CD46-transgenic mice

“…Several important target cells for gene therapy, including hematopoietic stem cells, 7 dendritic cells (DCs) 8 and malignant tumor cells, 9 express low levels of CAR. To overcome these drawbacks of Ad5 vectors, several groups (including ours) have developed Ad vectors composed of other human Ad serotypes, such as Ad serotype 7a, 10 11 4,11 and 35, 12-15 and Ads of animal origin, such as chimpanzee, 16 bovine, 17 mouse 18 and ovine. 19 Among these non-Ad5 vectors, those composed of human Ad11 and Ad35, which belong to subgroup B, are highly promising as gene transfer vectors for the following reasons.…”