Effective chemical virus inactivation of patient serum compatible with accurate serodiagnosis of infections.

OBJECTIVES: Highly pathogenic viruses such as EBOV are a threat to routine laboratory workers. Inactivation procedures with Triton X-100 0.1% and/or heat are currently recommended, but have unknown effects on the accuracy of serological testing. Furthermore, virus inactivation by Triton X-100 0.1% was shown to be ineffective in serum. This study aimed to demonstrate virus inactivation in serum by Triton X-100 1% and maintained accuracy of serological testing. METHODS: A panel of 19 serological tests was run on patient serum samples after treatment with Triton X-100 1%, 0.1%, and 0.1% + heat inactivation at 60°C for 1 h. Mean differences between measurements (bias) were calculated applying the Bland-Altman method. To determine effectiveness of virus inactivation, herpes simplex virus 1 (HSV-1) was spiked into medium containing 90% or 1% serum, and treated with Triton X-100 0.1% or 1%. Infectious titres were then determined on Vero cells. RESULTS: Serological measurements showed good agreement between controls and samples treated with Triton X-100 0.1% and 1%, with an estimated bias of 0.6 ± 9.2% (n = 258) and -0.1 ± 18.6% (n = 174), respectively. Discordant qualitative results were rare. Conversely, heat inactivation alone and combined with Triton X-100 0.1% triggered a bias of 17.5 ± 66.4% (n = 200) and 37.9 ± 79.8% (n = 160), respectively. Triton X-100 1% completely inactivated HSV-1 in 1% and 90% serum while Triton X-100 0.1% failed to do so in 90% serum. CONCLUSIONS: Unlike heat inactivation, Triton X-100 1% enabled accurate serological testing and completely inactivated HSV-1 in serum. This simple method could allow safe routine serological diagnostics in high-risk patients.

Clinical and immune response to undiluted and diluted smallpox vaccine.

QUESTION UNDER STUDY: To assess clinical reactions, immune responses and adverse events to undiluted, three- and sixfold diluted Lister strain vaccine stockpiled in Switzerland. METHODS: A prospective, triple-blinded, randomised, parallel group clinical trial was performed. RESULTS: From 2001 to 2007 104 persons with an indication for vaccinia vaccination were recruited. They had a median age of 33 years (range 18-65), 56 (53.8%) were re-vaccinees and 48 (46.2%) primary vaccinees. There was no statistically significant variation in the proportion of revaccinees between diluted and undiluted vaccine groups (75% vs 51%, p = 0.118). With an overall clinical take rate (major reaction) of 97.1% the majority of the vaccinia-naïve participants exhibited an at least fourfold increase of neutralising antibody titres (32/38, 84.2%) post-vaccination. Interestingly this proportion was lower among re-vaccinees (29/46, 63.0%, p = 0.048). No significant difference was observed in the take rate or at least fourfold seroconversion rate between the threefold and sixfold diluted vaccine doses. Adverse events were reported by 98 (94.2%) participants, not accounting for itching at the vaccination site. CONCLUSION: Subjects requiring immunisation were successfully (re-) vaccinated with undiluted as well as with three- or sixfold diluted vaccinia vaccine. Our findings complement previous studies with respect to the clinical take rate and immune response. The rate of adverse events was substantial but not unexpected and no severe adverse events occurred. In conclusion, the existing smallpox vaccine stockpile might be expanded by administering three- or sixfold diluted vaccine doses combined with a careful pre-vaccination screening and extensive instructions to vaccinees.

Peptide vaccines against hepatitis B virus: from animal model to human studies.

An estimated 400 million people are chronically infected with the hepatitis B virus (HBV). Chronic viral hepatitis infection incurs serious sequelae such as liver cirrhosis and hepatocellular carcinoma. Prevention and treatment, thus, represent an important target for public health. Preventive vaccines using HBsAg alone or combined with other antigens allow for the generation of neutralizing antibodies which effectively prevent infection in immunocompetent individuals. Cell-mediated immunological mechanisms are thought to be crucial in determining viral persistence or viral elimination. Therapeutic approaches aiming to shift cellular immunity towards viral elimination have been on the research agenda for many years. This paper summarizes pre-clinical and clinical results obtained with the use of immunogenic peptides formulated as vaccines to selectively boost cellular immune responses. Such vaccines are capable of generating cellular immune responses in animal models as well as in humans and represent an important step towards the development of a therapeutic vaccine against chronic hepatitis.

Perspectives: towards a peptide-based vaccine against hepatitis C virus.

Hepatitis C virus (HCV) is a widespread infectious disease in humans with the negative implication of becoming chronic in most persons. Patients infected with HCV are at risk of liver cirrhosis or hepatocellular carcinoma at later stages. In contrast to hepatitis A and hepatitis B, there is no immunization yet available, neither prophylactic nor therapeutic. Thus, there is an urgent need to develop a safe, protective vaccine against this fatal disease. Developing countries are even more at risk for HCV. There are currently a number of scientific approaches aimed towards solving this problem. Taking both risks and costs of immunization into consideration, a peptide-based vaccine may be a reasonable prophylactic protection. Also, it might be of therapeutic use in already infected patients by increasing a specific CTL response against HCV. In our lab, we are focusing on immunopotentiating reconstituted influenza virosomes (IRIVs) as carriers for immunogenic HLA-A2-restricted core epitopes to induce peptide-specific cytotoxic T lymphocytes (CTLs). The IRIVs are similar to liposomes, but in addition contain influenza-derived hemagglutinin and neuraminidase on their outer surface which makes them fusogenic, thus, permitting antigen delivery to host cells. So far, virosomes have been successfully used for vaccine development and as a result a virosomal vaccine against both influenza virus (Inflexal) BERNA) and hepatitis A virus (HAV) (Epaxal) BERNA) already exist on the market. This paper focuses on the importance of development of a successful vaccine against HCV and, more specifically, we discuss the use, advantages and disadvantages of a peptide-based vaccine. A brief report of our latest findings will be included.