Kinetics of Recombinant Adenovirus Type 5, Vaccinia Virus, Modified Vaccinia Ankara Virus, and DNA Antigen Expression In Vivo and the Induction of Memory T-Lymphocyte Responses

Abstract

While a new generation of vaccine vectors has been developed for eliciting cellular immune responses, little is known about the optimal routes for their administration or about the ramifications of the kinetics of in vivo vaccine antigen expression for immunogenicity. We evaluated the kinetics of vaccine antigen expression by real-time in vivo photon imaging and showed dramatic differences in these kinetics using different vectors and different routes of administration. Further, using a gamma interferon enzyme-linked immunospot assay to measure T-lymphocyte immune responses, we observed an association between the kinetics of vaccine antigen expression in vivo and the magnitude of vaccine-elicited memory T-lymphocyte responses. These results highlight the utility of the real-time in vivo photon-imaging technology in evaluating novel immunization strategies and suggest an association between the kinetics of vaccine antigen clearance and the magnitude of vaccine-elicited T-lymphocyte memory immune responses.While a new generation of vaccine vectors has been created to induce cellular immune responses, we know little about how to use them to maximize the generation of memory T-lymphocyte populations. Recombinant viral vectors and plasmid DNA constructs have been shown to elicit potent cellular immune responses (2,7,8,13,15,16,21,23). However, little has been done to evaluate the optimal routes of administration of these vaccine modalities and the relationship between the route of administration and in vivo vaccine antigen expression. Moreover, we do not fully understand the ramifications of the kinetics of vaccine antigen expression for immunogenicity.The in vivo evaluation of new vaccine vectors to select optimal routes of administration, dose, and biodistribution has been difficult, requiring serial sacrifice of laboratory animals and assessment of individual organs for vaccine antigen expression. To simplify this process of vaccine evaluation, we have adopted an in vivo imaging system (IVIS) to measure the expression of luciferase by vaccine vectors. This imaging strategy harnesses the ability of the luciferase protein to catalyze the light-producing oxidation of the small molecule luciferin. Luciferin is inoculated into mice that have received luciferaseexpressing immunogens, and the quantity of light emitted by this reaction is monitored in living mice (6).The use of in vivo imaging and luciferase expression (4), a technology developed for evaluating gene therapy strategies, is well suited for studying these novel vaccine vectors. We have recently shown that IVIS can be used to monitor the distribution and kinetics of vaccine vectors in the living mouse (12). The present study was done to explore the impact of the route of vaccine administration on vaccine antigen expression. In the process of doing these studies, we observed a striking association between the kinetics of antigen expression in vivo and the induction of long-term memory T cells.

Modified Vaccinia Virus Ankara-Based Vaccine Vectors Induce Apoptosis in Dendritic Cells Draining from the Skin via both the Extrinsic and Intrinsic Caspase Pathways, Preventing Efficient Antigen Presentation

“…4 and 7). These data may also indicate why when poxvirus vectors are used levels of T cell response are generally lower than in vaccination strategies that utilize replicationdeficient adenovirus vectors (9,27,61,62,77). At this moment, it is not known how MVA-infected ALDC affect surface receptor expression of bystander cells, but our preliminary data indicate that one or more soluble factors are involved in this phenomenon.…”

Anti-Gamma Interferon Antibodies Enhance the Immunogenicity of Recombinant Adenovirus Vectors

“…Previous studies from our laboratory have shown that rAd expressing a luciferase transgene (rAd-Luc) generates highlevel transgene expression for approximately 1 week in wildtype mice (20). In these studies, differences between the clearance of transgene expression in wild-type and athymic mice after rAd-Luc administration suggested that the kinetics of this clearance might be associated with the generation of cellular immune responses.…”

“…In these studies, differences between the clearance of transgene expression in wild-type and athymic mice after rAd-Luc administration suggested that the kinetics of this clearance might be associated with the generation of cellular immune responses. In fact, a relationship between the rate of clearance of transgene expression and the generation of longterm memory cellular immune responses was noted (20). Since vaccine antigen (Ag) clearance can limit the magnitudes of adaptive immune responses, and these responses are associated with the magnitudes of the elicited memory cellular responses, we are evaluating changing the kinetics of rAddelivered antigen clearance as a strategy for enhancing rAd vaccine-elicited memory responses.…”

Non-classical Natural Killer T Cells Modulate Plasmid DNA Vaccine Antigen Expression and Vaccine-elicited Immune Responses by MCP-1 Secretion after Interaction with a β2-Microglobulin-independent CD1d

“…Innate Immune Cells-We have previously shown that antigen expression during the first 3 days following plasmid DNA inoculation influenced the strength of the vaccine-induced memory T cell immune response (1). Because DNA vaccination is associated with the accumulation of both NK and NKT cells at the site of inoculation (2), we sought to determine whether these cell populations modulate plasmid DNA-elicited adaptive immune responses.…”

“…Plasmid DNA vaccine-induced T cell memory responses are potentiated by innate immune responses that are generated during the first days after vaccination (1). At that time Natural Killer (NK) 2 and Natural Killer T (NKT) cells are attracted to the site of vaccine administration (2).…”