Email from Dr Ruth Watkins November 21 2007
The zones to control movement of animals do not prevent the spread of the infection.- as we have witnessed in Europe this summer.The partial vaccination that a voluntary scheme would lead to will also likely make no difference to the spread of BTV-8 either. I think all the countries at risk have an interest in the control of BTV-8. It is unfortunate that the economic interest even temporary advantage appears to make neighbouring areas so ill disposed.
As a virologist I could recommend the following using an inactivated BTV-8 vaccine
1 The import of vaccinated and uninfectious animalsVaccination of animal, then testing once when response to vaccination deemed to be maximum using both antibody and RNA tests. If the animal is antibody positive and virus RNA negative then it is not infectious and is protected against BTV-8 infection. It may have been infected more than 6 months in the past. Or it may never have been infected and has responded to the vaccine and has made a protective immune resonse.
2 The import of vaccinated and never infected animals Test the animal to be vaccinated for both antibody and virus RNA. If it is negative vaccinate. Once the response to vaccine is deemed to be at a maximum (likely 2 weeks after the second dose) retest for both anitbody and virus RNA. If the animal is positive for antibody and negative for virus RNA then it has responded to vaccination and never been infected. If Ireland and other coutnries would agree to this, option 2, I think this could be a basis to move forward on negociations with them.
Caveat. Pirbright is at present using a generic antibody and RNA test for BTV. This is correct strategy in the case of our outbreak (they do checks to exclude the circulation of additional BTV serotypes such as 1) Whilst it is right for options 1 and 2 above to continue with this generic test for BTV virus RNA (so detecting any BTV virus including BTV-8) the antibody screening after vaccination should include a BTV-8 specific antibody test, not simply a test for antibody to any BTV virus. This would confirm a response to BTV serotype 8 surface proteins which is likely to be highly correlated with protection against BTV-8 infection. Therefore the importing country can be assured that it is not going to import an animal infected in transit for example, because the vaccinated animal is protected from infection even if it is bitten by an infected female midge before it makes the journey.
yours sincerelyRuth Watkins