T cell-mediated and non-specific inflammatory mechanisms contribute to the skin pathology of HPV 16 E6E7 transgenic mice

ISCOMATRIX™ adjuvant: an adjuvant suitable for use in anticancer vaccines

Human Papillomavirus type 16 (HPV16) E6 and E7 oncoproteins are associated with cervical cancer development and progression and can therefore be used as target antigens for cancer immunotherapy. In this study we evaluated the immunogenicity in mice, of different vaccine formulations using recombinant HPV16 derived E6E7 or E7GST fusion proteins. When co-administered with ISCOMATRIX adjuvant, these E6E7 proteins consistently induced E7 specific CTL, in vivo tumor protection, antibody and DTH responses. ISCOMATRIX adjuvant has been developed for use in the formulation of novel human vaccines and has been evaluated for safety and toxicity in human trials. A formulation containing aluminum hydroxide (Al(OH)3) gave a lesser degree of E7 specific antibody, and no local E7 specific CTL response but similar DTH and tumor protection. These findings demonstrate the potential of ISCOMATRIX adjuvant to stimulate both cellular and humoral immune responses to endogenously processed target antigens, and hence is the preferred adjuvant when CTL responses are desirable.

Evasion of host immunity directed by papillomavirus-encoded proteins

The nature of the interaction between papillomaviruses (PV) and their infected host has led to the identification of ways in which the viral oncoproteins can transform the infected host cells into cancer cells. As viral persistence is required for malignancy, and persistence requires avoidance of immune attack by the host, defining the relationship between PV and the immune system is also paramount in understanding tumorigenesis. It has emerged that PV have evolved several ways in which to prevent clearance by the host immune system. The limitation of the PV replication cycle to the epithelium, together with low level expression of the virus proteins and an absence of inflammation, minimises the exposure of virus to immune cells. In addition, more recently it has been shown that, like many other viruses, PV can directly subvert the immune response, including interference with the interferon pathway, modulation of antigen presentation, inhibition of interleukin-18 activity and down-regulation of major histocompatibility class I on infected cells. Collectively these mechanisms explain how PV lesions are able to persist for long periods of time in immunocompetent hosts.