Evaluation of recombinant avian influenza compared to inactivated vaccines to induce immune response in chicken

Abstract EN

The present Avian Influenza epidemic in Egypt is consider one of the major problems facing the poultry field and caused by circulation of genetically and antigenetically diverse influenza H5N1 viruses.

This problem is controlled by applying vaccination.

The objective was to determine the AI H5 recombinant vaccines efficacy (rHVT-H5, rFP-AIH5 (Scotland and Ireland), k rND-AI and k rBucAI+ND) against classical and variant field HPAI H5N1 viruses in comparison to the traditionally inactivated whole AI virus vaccines as K R H5N1 / Egy, k H5N2 and k combined AI+ND vaccines.

A single dose of the different types of vaccines either recombinant or inactivated whole virus vaccines was administered at different ages of chicken.

Eight chicken groups were vaccinated with 8 vaccines and challenged after 4 weeks post vaccination to measure the protection %.

Fecal and tracheal swabs were taken after 2 day post challenge to detect viral shedding.

It was found that, live rFPAI-H5 of both Scotland and Ireland strains induced poor clinical protection with high level of virus shedding.

While, inactivated rND-AI, live rHVT-H5 and inactivated rBuc-AI+ND vaccines induced high protection rates ranged from 86.7% to 93.3% against both classical and variant HPAI viruses with a decrease or suppression of viruses shedding.

In a parallel way, the inactivated whole virus AI vaccines either K R H5N1 / Egy, k H5N2 or k AI+ND induced a protection rates ranged from 85.7% to 100% with a high decrease in virus shedding levels.

The data clearly indicate that inactivated whole AI virus and inactivated recombinant vaccines confers high levels of clinical protec tion with suppression in viral shedding compared to that of live recombinant vaccines except rHVTH5 vaccine which induce a great level of protection and decrease in viral shedding in SPF chicken.