Comparative Evaluation of HVT-IBD Vector, Immune Complex, and Live IBD Vaccines against vvIBDV in Commercial Broiler Chickens with High Maternally Derived Antibodies

Abstract

Infectious bursal disease (IBD) causes increased mortality and severe immunosuppression in commercial chickens. Currently, vaccination mainly used to control IBD. In this study, Group A (n = 30) received the HVT-IBD vector vaccine (Vaxxitek®) s/c and Group B (n = 30) received the immune complex vaccine (Bursa-Plex®) s/c at 1 day of age. Group C (n = 30) received a single dose of intermediate plus vaccine (228E) through the eye-drop route at 14 days of age. Group D (n = 30) was vaccinated twice with the intermediate vaccine (D78) at 12 and 22 days of age by eye-drop. Group E (n = 30) had the same treatment as group D along with the IBD killed vaccine (Nobilis G®) at 5 days of age. The PC (n = 20) and NC (n = 20) groups were non IBD vaccinated birds either challenged or not with vvIBDV, respectively; 20 chicks from each group were challenged with vvIBDV at 4 weeks of age. Based on clinical signs, postmortem gross lesions, histopathological changes, mortality rate, feed conversion rate, serology, bursal and spleen indices, the HVT-IBD vector vaccine administered was found to be safer and provided better protection against the vvIBDV challenge. The use of a killed IBD vaccine at an earlier age in broilers strengthened the protection induced by double doses of intermediate vaccines in broilers with high maternally derived antibodies against the vvIBDV challenge.

The expression in plants of an engineered VP2 protein of Infectious Bursal Disease Virus induces formation of structurally heterogeneous particles that protect from a very virulent viral strain

“…Similarly, in our experiments, the immunization with the VP2-BP were able to induce not only a strong immune response towards vvIBDV but also protection from the onset of the disease and, in most animals, of the bursal lesions associated to viral infection. A recently published article comparing the efficacy in broilers of different commercially available new generation vaccines [ 44 ] showed that the best results, in terms of protection against challenge with vvIBDV, were obtained using the HVT-IBD vector vaccine ( Vaxxitek ®) and the immune complex vaccine ( Bursa-Plex ®). Both these vaccines are based on live viruses and could present some environmental safety concerns.…”

Live unattenuated vaccines for controlling viral diseases, including COVID‐19

“…It is administered subcutaneously to day‐old chicks even in the presence of maternally derived antibodies (MDA). This LUV was found to be equal to or better than that of conventional LAVs in efficacy 20,21 . The success of this LUV indicates a potential approach to circumventing the MDA interference, which is a problem in vaccination against multiple viral diseases.…”

“…The AVAs used for AVA LUV production are from the plasma or serum of recovered or vaccinated homologous hosts, which are of limited supply and contamination risk 16‐21 . Humanized mAbs could be employed for the production of AVA LUVs because they can efficiently inhibit viral replication and aid complements and immune cells to destroy relevant viruses, and have been used successfully in the therapy of related viral diseases 23,24,29,30,35 .…”

“…ADE is a mechanism through which dengue viruses, feline coronaviruses, SARS coronavirus, and HIV viruses take advantage of low levels of antiviral antibodies to infect host cells 65 . Moreover, AVA LUVs and AGA LUVs could circumvent the interference of MDA, as indicated by the AVA LUV used for chicken infectious bursal disease 20,21 . Meanwhile, the protection effect of MDA could be unaffected with inoculation of AVA LUVs, as the LUVs can be bound with neutralizing antibodies before inoculation, and the vaccine virus cannot replicate efficiently in vivo.…”

“…Live vaccines are live attenuated vaccines (LAVs), with some exceptions of live unattenuated vaccines (LUVs) 12‐21 . LAVs are excellent in efficacy and cost, but they are time‐consuming in development and dangerous to those with immunodeficiency.…”