by Dr Chris Oura, head of the Non-Vesicular Reference Laboratories, Institute for Animal Health, Pirbright, UK.
With vaccination, you do not have to worry about giving drugs or treating the animals. Once you have got an effective immune response through vaccination then that animal is immune to that particular virus, bacteria or parasite.
We have seen many examples of where vaccination has been used effectively in the veterinary world; the shining example would be Rinderpest. In 1962, a vaccine was produced that was cheap, effective and protected animals for life. We are now looking towards declaring, in the next couple of years, that we have eradicated rinderpest worldwide. That is a massive achievement and has only been achieved with one other virus in the world – smallpox.
Some other types of diseases are more complicated as the antibodies that are stimulated in the immune system are not protective. Instead, another arm of the immune system which is cell mediated is responsible for protection. It is sometimes quite difficult to stimulate both parts of the immune system at once. So you need a different type of vaccine which actually stimulates these cells as well as the antibodies and that is what many people in many universities around the world have been trying to develop.
Vaccines for malaria and HIV are problematic to produce because you have to stimulate all the different parts of the immune system in order to get protection. So what goes into the vaccine is absolutely vital.
In some cases you might be able to take a virus, kill it, put it in the animal and get protection. But if you do that with another virus, you get no protection. In many cases you need to engineer a far more sophisticated vaccine to stimulate the necessary immune response.
Another problem we have is that pathogens are often one step ahead. They are able to evade the immune response and break through vaccines very quickly because they are evolving and changing all the time. So you cannot just produce a vaccine and say, “job done, let’s move onto the next one” because within a short period of time that particular pathogen may have broken through the vaccine. This takes you back to square one and you have to start working on a new and improved vaccine against the pathogen. It is a constant battle between the virus and the vaccine.
For developing countries, it is absolutely vital that we work on the diseases that are affecting their livestock and try to produce these cheap, effective vaccines. Ultimately, however, the people that produce the vaccines are commercial companies and they have to have the prospect of making money, which is why they have primarily focused on diseases that affect developed countries. So there has to be some mechanism whereby the pharmaceutical companies are given the push, the money or whatever is needed to produce those vaccines for the poorer countries.
At the end of the day, what we are all looking for is an effective control against disease in livestock and without a doubt, the best method is vaccination.