We have recently demonstrated that immunization with hepatitis C virus-like particles (HCV-LPs) generated in insect cells can elicit both humoral and cellular immune responses in BALB͞c mice. Here, we evaluate the immunogenicity of HCV-LPs in HLA2.1 transgenic (AAD) mice in comparison to DNA immunization. HCV-LP immunization elicited a significantly stronger humoral immune response than DNA immunization. HCV-LP-immunized mice also developed stronger HCV-specific cellular immune responses than DNA-immunized mice as determined by using quantitative enzyme-linked immunospot (ELISpot) assay and intracellular cytokine staining. In BALB͞c mice, immunization with HCV-LPs resulted in a >5 log10 reduction in vaccinia titer when challenged with a recombinant vaccinia expressing the HCV structural proteins (vvHCV.S), as compared to 1 log 10 decrease in DNA immunization. In HLA2.1 transgenic mice, a 1-2 log10 reduction resulted from HCV-LP immunization, whereas no reduction was seen from DNA immunization. Adoptive transfer of lymphocytes from HCV-LP-immunized mice to naive mice provided protection against vvHCV.S challenge, and this transferred immunity can be abrogated by either CD4 or CD8 depletion. Our results suggest that HCV-LPs can induce humoral and cellular immune responses that are protective in a surrogate HCV challenge model and that a strong cellular immunity provided by both CD4 and CD8 effector lymphocytes may be important for protection from HCV infection.

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Persistent infection with human papillomaviruses (HPV) is a prerequisite for the development of cervical cancer. Vaccination with virus-like particles (VLP) has demonstrated efficacy in prophylaxis but lacks therapeutic potential. HPV16 L1E7 chimeric viruslike particles (CVLP) consist of a carboxy-terminally truncated HPV16L1 protein fused to the amino-terminal part of the HPV16 E7 protein and self-assemble by recombinant expression of the fusion protein. The CVLP are able to induce L1-and E7-specific cytotoxic T lymphocytes. We have performed a first clinical trial to gain information about the safety and to generate preliminary data on the therapeutic potential of the CVLP in humans. A randomized, double blind, placebo-controlled clinical trial has been conducted in 39 HPV16 mono-infected high grade cervical intraepithelial neoplasia (CIN) patients (CIN 2/3). Two doses (75 lg or 250 lg) of CVLP were applied. The duration of the study was 24 weeks with 2 optional visits after another 12 and 24 weeks. The vaccine showed a very good safety profile with only minor adverse events attributable to the immunization. Antibodies with high titers against HPV16 L1 and low titers against HPV16 E7 as well as cellular immune responses against both proteins were induced. Responses were equivalent for both vaccine concentrations. A trend for histological improvement to CIN 1 or normal was seen in 39% of the patients receiving the vaccine and only 25% of the placebo recipients. Fifty-six percent of the responders were also HPV16 DNA-negative by the end of the study. Therefore, we demonstrated evidence for safety and a nonsignificant trend for the clinical efficacy of the HPV16 L1E7 CVLP vaccine. ' 2007 Wiley-Liss, Inc.Key words: cervical cancer; clinical trial; immunization; antibody; T cell Genital infection with human papillomavirus (HPV) is one of the most common sexually transmitted diseases. Various molecular and epidemiological studies have documented a correlation between infection with ''high risk'' HPV types and premalignant or malignant tumors of the anogenital tract. 1,2 It is widely acknowledged that a causal relationship exists between persistent HPV infection and development of cervical intraepithelial neoplasia (CIN) and cervical cancer. 3,4 There are over 100 known papillomavirus types that are stratified into low and high risk, based on their association with malignant and invasive lesions. More than 95% of invasive cervical cancers are positive for HPV-DNA, mainly from HPV types 16 (50%) and 18 (20%). Moreover, HPV16 can be detected in 30270% of all HPV-positive high grade CIN patients. 5,6 The prevalence of HPV16 in other intraepithelial neoplasias is even higher, e.g., 70280% in high grade vulvar intraepithelial neoplasia. 7 Whereas for low grade CIN a high spontaneous recovery rate is observed 6,8 high grade CIN regress less often particular at higher age when lesions are more persistent. 9 Because of the potential progression of high grade CIN to invasive cancer, 10 a thorough evaluation consisting of colp...