Biomedical subjects

Ian Ramshaw

Publications and source records attributed to Ian Ramshaw.

3 recordsLinked to original sources

PubMed2004

A polytope DNA vaccine elicits multiple effector and memory CTL responses and protects against human papillomavirus 16 E7-expressing tumour.

Vaccine-induced CD8 T cells directed to tumour-specific antigens are recognised as important components of protective and therapeutic immunity against tumours. Where tumour antigens have pathogenic potential or where immunogenic epitopes are lost from tumours, development of subunit vaccines consisting of multiple individual epitopes is an attractive alternative to immunising with whole tumour antigen. In the present study we investigate the efficacy of two DNA-based multiepitope ('polytope') vaccines containing murine (H-2b) and human (HLA-A*0201)-restricted epitopes of the E7 oncoprotein of human papillomavirus type 16, in eliciting tumour-protective cytotoxic T-lymphocyte (CTL) responses. We show that the first of these polytopes elicited powerful effector CTL responses (measured by IFN-gamma ELISpot) and long-lived memory CTL responses (measured by functional CTL assay and tetramers) in immunised mice. The responses could be boosted by immunisation with a recombinant vaccinia virus expressing the polytope. Responses induced by immunisation with polytope DNA alone partially protected against infection with recombinant vaccinia virus expressing the polytope. Complete protection was afforded against challenge with an E7-expressing tumour, and reduced growth of nascent tumours was observed. A second polytope differing in the exact composition and order of CTL epitopes, and lacking an inserted endoplasmic reticulum targeting sequence and T-helper epitope, induced much poorer CTL responses and failed to protect against tumour challenge. These observations indicate the validity of a DNA polytope vaccine approach to human papillomavirus E7-associated carcinoma, and underscore the importance of design in polytope vaccine construction.

Amino Acid Sequence↗

PubMed2003

Dendritic cells infected with a vaccinia virus interleukin-2 vector secrete high levels of IL-2 and can become efficient antigen presenting cells that secrete high levels of the immunostimulatory cytokine IL-12.

Dendritic cell (DC) therapies using DC presenting tumor antigen/s can induce CD8(+) CTL that mediate tumor eradication, nonetheless many patients remain unresponsive. Thus, cytokine gene vectors applied to DC may amplify these responses. Herein, we examined the responses that monocyte-derived DC (at different maturational stages) make when infected with a vaccinia virus-interleukin-2 (VV-IL-2) vector in vitro. VV-IL-2-infected DC secreted significant levels of bioactive IL-2 and maintained their antigen presentation function. However, we show that DC are exquisitely sensitive to their local antigenic microenvironment, and that responses generated by one antigen can be altered by another. VV-IL-2 infection of immature DC led to DC activation (upregulation of CD80, CD86 and class II surface molecules) when the virus was propagated through xenogeneic, but not syngeneic, mammalian cells; these DC secreted IL-10 and tumor necrosis factor-alpha (TNF-alpha), but not IL-12. In contrast, after VV-IL-2 infection (regardless of their mammalian cellular context), IFNgamma/LPS-matured DC inevitably downregulated their antigen presenting machinery. In conclusion, immunostimulatory DC can be generated by VV-IL-2, but this depends upon (i) infecting immature DC only, (ii) the mammalian cells through which the virus is prepared and (iii) individual donors; hence donors must be screened to assess their specific responses.

Antigen Presentation↗

PubMed2003

DNA vaccination.

Few advances in the history of vaccination have had as quick a passage (approximately 10 years) from their discovery to clinical trials and, hopefully soon, registration as DNA immunisation. A very clear picture has now emerged of the recognition of the CpG-motif rich, chimaeric bacterial DNA by dendritic cells (antigen-presenting cells [APCs]) and the subsequent activation of T lymphocytes. Both humoral and comprehensive cell-mediated responses occur in both mice and primates. No significant safety concerns have been observed following administration to several hundred human volunteers, including some children. Of special interest is the generation of strong and high avidity CD8+ cytotoxic T lymphocyte (CTL) responses in primates, following priming with chimaeric DNA and subsequent boosting with a chimaeric live viral vector, such as an attenuated poxvirus or adenovirus. The DNA may also be used as a highly potent adjuvant, inducing mainly T helper (Th)1 responses. Advantages include its potential use in the presence of antibody to the targeted infectious agent and a generally simple manufacturing process.

Animals↗