A promising vaccine against hepatitis C has been formulated by Italian scientists who have developed a new method for producing vaccines – basing them on chimpanzee viruses. Although harmless to humans, chimpanzee viruses are well suited as they are unknown to the human immune system, which is therefore able to develop an immune response that is much more powerful than that induced by the classic viruses in use today.
As reported in two articles in the journal Translational Medicine, published by Science, the technique comes from a company called Okairos, whose laboratories are situated within the Naples CEINGE biotechnology centre.
As Alfredo Nicosia told ANSA, the hepatitis C vaccine has already passed its first experimental phase of tests on human subjects, but this is just the first of a long series and in fact, as he revealed, ”our biotech is working on a series of vaccines including one against malaria, one against the RSV virus and a universal vaccine against influenza – as well as a vaccine against Ebola. All these candidate vaccines are based on our adenoviral vectors derived from chimpanzees and for the moment they have been successfully tested on animal models to demonstrate their efficacy before clinical trials with humans”.
The development of a vaccine is based on using so-called ‘vectors’, or little genetic ‘vessels’ that carry the antigen into the human immune system. These vectors are created using inactive viruses (that have been rendered harmless). Usually human adenoviruses are used, but as these viruses are well known to our bodies, (just think of the common cold, for example), they don’t tend to provoke a strong immune reaction.
It was here that the idea arose of using chimpanzee viruses as they are harmless but also unknown to our bodies and therefore able to ‘tease out a reaction’ from the immune system in a much stronger way.
The Italian researchers have gathered a series of samples of chimpanzee adenovirus and have used these to create new vectors.
Of all these vaccines so far developed using these vectors, the most advanced stage of development has been reached by the anti-hepatitis C vaccine. ”It was recently injected into human volunteers and it proved to be very safe, i.e. free of side-effects, as well as very effective in its ability to induce a strong and lasting immune response against HCV,” Mr Nicosia said. ”Furthermore, the vaccine has prove capable of inducing cytotoxic T-cells (also know as T CD8), that are our only real weapon against such subtle viruses as hepatitis C and HIV”.
”In order to measure the degree of immune response induced by the candidate vaccine in human volunteers, we took blood samples from those who had been vaccinated and isolated their cytoxic T-cells, measuring quantities and abilities to react to HCV antigens. Now, in collaboration with the US National Institute of Health, we have asked for experiments to be authorised to assess the efficacy of our virus and we are hoping to start with Phase II clinical trials in the USA by the end of the first quarter of 2012. This will be at two US university clinics: the Johns Hopkins University in Baltimore and the University of California San Francisco”.