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Immune responses to non-structural protein 3 (NS3) of bovine viral diarrhoea virus (BVDV) in NS3 vaccinated and naturall

Immune responses to non-structural protein 3 (NS3) of bovine viral diarrhoea virus (BVDV) in NS3 vaccinated and naturally infected cattle. N.J.Young , C.J.Thomas, I. Thompson, M.E. Collins, J. Brownlie Royal Veterinary College, Hertfordshire, UK. BVDV – Introduction. Worldwide prevalence

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Immune responses to non-structural protein 3 (NS3) of bovine viral diarrhoea virus (BVDV) in NS3 vaccinated and naturall

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  1. Immune responses to non-structural protein 3 (NS3) of bovine viral diarrhoea virus (BVDV) in NS3 vaccinated and naturally infected cattle N.J.Young, C.J.Thomas, I. Thompson, M.E. Collins, J. Brownlie Royal Veterinary College, Hertfordshire, UK. 2nd European Symposium on BVDV Control, Porto, Portugal

  2. BVDV – Introduction • Worldwide prevalence • 1998 – 95% dairy herds naturally exposed • Economic losses • Reduced fertility • Abortion and congenital defects • Birth of persistently infected calves increasing herd infection Royal Veterinary College

  3. BVDV – The virus • Virus – ss +ve sense RNA, 12.5Kb • Proteins – 4 structural and 4/5 non-structural Royal Veterinary College

  4. Immunity to non-structural protein 3 (NS3) • NS3 • Stimulates cellular immunity • B cell epitopes identified • Aim • Investigate immunity to NS3 in calves after DNA vaccination followed by virus challenge Royal Veterinary College

  5. NS3 cDNA from type 1a BVDV cloned into mammalian expression vector Calves vaccinated intradermally with 500µg DNA on 3 occasions V 1 V 2 V 3 Challenge 21 -42 -63 0 -21 Study design Royal Veterinary College

  6. Rectal temperatures • Mean rectal temperatures reduced in the NS3 vaccinated calves Royal Veterinary College

  7. Individual rectal temperatures of the NS3 vaccinated calves • Pyrexia prevented in two animals and reduced in a third Royal Veterinary College

  8. Nasal discharge • Delayed onset of nasal discharge in NS3 vaccinated calves Royal Veterinary College

  9. Anti-NS3 antibodies • Identified one vaccinated responder with NS3 specific antibodies before challenge. Remaining animals seroconverted to NS3 post-challenge Royal Veterinary College

  10. Virus isolation from nasal mucosa • The vaccinated group demonstrated reduced viraemia and faster clearance in the nasal mucosa samples Royal Veterinary College

  11. Conclusions • NS3 vaccination • Level of protection in all calves, with one demonstrating specific humoral response • Anti-NS3 antibodies not neutralising but virus shedding still reduced • Cellular immunity not identified in this study but will be investigated in the future as may play some part in the protection seen in all vaccinated calves Royal Veterinary College

  12. Future work • Assessment of viral load in vaccinated and control animals by quantitative RT-PCR • Investigation into proliferation responses to NS3 in challenged animals Royal Veterinary College

  13. Acknowledgements • PhD supervisors: • Prof. Joe Brownlie • Dr. Margaret Collins • Research Group • Dr Carole Thomas • Dr Jude Heaney • Novartis Animal Vaccines Ltd • Dr Ian Thompson • BBSRC Royal Veterinary College

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