Foot-and-mouth disease vaccine trial on cows

Foot-and-mouth disease vaccine trial on cows


There is a large outbreak of foot and mouth
disease in south-east Asia. It appears that the current vaccine is not proving adequate
protection. We need to develop a new vaccine that’s more closely matched and so will
give better protection to the virus that is circulated in that area. We have developed
a new strain of vaccine and we need to carry out a study in animals to show whether this
vaccine will protect against the virus that is circulating in south-east Asia. Based on
those results we can advise those countries whether this vaccine they should use to vaccinate
millions of animals and protect them from an outbreak.
We have got 18 animals in this trial of which 15 will be vaccinated and then we have to
have 3 controls to show that the virus we are using will actually cause diseases. We
hope and expect that the animals that are being vaccinated will either show no clinical
signs at all, they will be fully protected or they will show very mild clinical signs.
The animals that are not protected at all would eventually show severe signs of foot-and-mouth
disease but we don’t allow them to get to that point. As soon as we are sure that they
are infected and that is at a stage when they have mild or moderate clinical signs we then
remove them from the trial. The study design has being used for probably
50 years and we know that results we are getting from these vaccine protection studies do translate into
demonstrating the vaccine will be efficacious in the field. Because we know precisely how
much virus we are giving each animal then this means that we can use smaller groups
sizes to prove whether that vaccine is going to be protective or not. We will vaccinate
these animals next week and then we will leave them 21 days and then we will challenge them
and we will know probably within 3-4 days whether they are protected from infection
or not. The study goes out 8 days post vaccination. You usually know quite quickly whether the
vaccine is going to be protective or not. If the vaccine is protective then we can give
advice that can be used in the field in the countries that are suffering from the disease.
If it isn’t protective then we have to go and find a different vaccine formulation but
that is very important information because then we are not advising the companies or
governments to use a vaccine that will know will not provide full protection in the field,
so both results are very important. If this trial is successful, we can go straight into
production into growth in 10,000 litre vessels to make thousands and millions of doses of
vaccines. Theoretically, there could be a useable vaccine on the market in probably
6 weeks to 2 months. If the trial isn’t successful, then we have
to go back to the drawing board and go back to looking at other isolates of virus which
we have taken from the field and then we have to get them to grow in tissue culture. It
could be another 3-4 months at least before we are in the position to have another virus
that can be made into a vaccine to test again. These studies because of the nature of the
disease are monitored very closely as a minimum the animal staff will come in here at least
twice a day to make sure to formally examine the animals to look at their clinical signs.
We have highly trained staff who have huge amount of experience of this disease and know
the process that the animals go through and in the run up to them showing disease so they
are very familiar with the early clinical signs and that is very important that we can
control the severity of infection closely. There is always the question of you are deliberating
infecting animals with the virus that is going to cause disease and then of course we have
to kill the animals at the end of that study because they can’t be released back onto
the farm because they have been infected and could carry foot-and-mouth disease that could
have devastating effect on the UK’s agricultural system.
We have gone through an extensive laboratory studies to choose what we believe is a vaccine
that will protect these animals for foot-and-mouth disease and then we are using 18 animals to
test a vaccine that will be used to protect millions of animals and to stop them getting
disease. So even though I don’t think any of us likes to carry out these types of studies
they are essential if we are going to protect the larger livestock population around the
world.

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