R. Forero*1, M. Gaimard1, S. Lesceu1, C. Redal1, J-E. Drus1, C. Lefebvre1, P. Pourquier. Innovative Diagnostics, 310 rue Louis Pasteur, 34790 Grabels – FRANCE . *Corresponding Author: rafael.forero@innovative-diagnostics.com
Avian infectious laryngotracheitis (ILT) is a respiratory disease of chickens caused by the Gallid 1 herpesvirus. The ILT virus causes significant economic losses, which could be reduced by vaccination using any conventional vaccine (TCO and CEO) or vectored vaccines whose Commercially used viral vectors are Turkey Herpesvirus (HVT) or Smallpox Virus (FPV). Since conventional serology kits do not efficiently detect seroconversion to vectored vaccines, IDvet has developed unique and innovative indirect ELISA tests based on recombinant glycoproteins to monitor vectored vaccines.
Flocks of birds vaccinated with three different commercially available vectored vaccines (HVT-gI, FPV-gB and HVT-gD) were serologically evaluated at different weeks post-vaccination (SPV) using the following indirect ELISA kits:
- ID Screen® ILT gI: based on a recombinant gI protein for the detection of antibodies against the gI protein of the ILT virus.
- ID Screen® ILT gB: based on a recombinant gB protein for the detection of antibodies against the gB protein of the ILT virus.
- ID Screen® ILT gD: based on a recombinant gD protein for the detection of antibodies against the gD protein of the ILT virus.
HVT-gI Vaccine Monitoring: Sera from two batches of breeding stock (origin: Spain), vaccinated with a recombinant HVT-gI vaccine at day one of age, were analyzed in parallel using the indirect ID Screen® ILT gI and ID Screen® ILT gB ELISAs. The birds were bled at seven and nine weeks of age.
FP-gB vaccine monitoring: Sera from 4 batches of commercial layers (origin: Mexico), vaccinated with the recombinant FP-gB vaccine at 21 days of age, were analyzed in parallel with the indirect ELISA kits ID Screen® ILT gB and ID Screen® ILT gI. Birds were bled at five to seven weeks of age.
HVT-gD Vaccine Monitoring: Sera from four batches of broiler chickens (origin: USA), vaccinated with a recombinant HVT-gD vaccine at day one of age, were analyzed in parallel using the ID Screen® ILT gD and ID Screen® ILT gI ELISAs. The birds were bled at six weeks of age.
Results:
HVT-gI Vaccine Monitoring: The indirect ELISA detected antibodies between seven to nine SPVs with the HVT-gI vaccine, with titres between 3500 and 4500. There is no detection of HVT-gI vaccine-induced seroconversion with the indirect gB ELISA.
FP-gB vaccine monitoring: The indirect gB ELISA detected antibodies between two and five SPV with the FP-gB vaccine, with titres between 5000 and 9000. There is no detection of seroconversion induced by the FP-gB vaccine with the indirect gI ELISA .
HVT-gD Vaccine Monitoring: The indirect gD ELISA detected antibodies to all six SPVs with the HVT-gD vaccine, with titres between 3000 and 9000. There is no detection of seroconversion induced by the HVT-gD vaccine with the indirect gI ELISA.
Conclusion:
Antibodies generated by the recombinant ILT vaccines were specifically detected by indirect ELISA, based on the associated ILT glycoprotein. Consequently, serology remains a good tool to monitor antibody titers after vaccination.
ID Screen® ILT gI, gB or gD iELISA are unique tests designed to efficiently monitor recombinant vaccines.