Vaccination with FMD vaccines
Vaccines are defined as suspensions of attenuated or killed micro-organisms for the prevention of disease or disease symptoms.When an animal is vaccinated:
The immune system is stimulated.
Antibodies are produced against a specific infectious agent.
If the animal is infected by this agent, the antibodies play a role in neutralizing the infectious agent and preventing disease.
FMD viruses produce both structural (SP) and non-structural proteins (NSP) also known as 3ABC proteins. These proteins play a role in the stimulation of the immune system and the subsequent production of antibodies. SP are important in the production of neutralising antibodies and therefore protection against future disease challenges. Antibodies against NSP do not offer clinical protection.
Modern FMD vaccines are based upon highly purified antigens that are free from NSP (3ABC). After vaccination antibodies are only induced against SP. However, in the case of a FMD field virus infection, antibodies against both SP as well as NSP are produced.
When an animal is tested for FMD, the presence and type of antibodies in the blood are measured. As can be seen from the above, it is now possible to differentiate between animals infected with FMD virus and animals vaccinated against FMD. The vaccine can thus be used as a “marker-vaccine”.
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