Simultaneous Protective Immune Responses of Ducks against Duck Plague and Fowl Cholera by Recombinant Duck Enteritis Virus Vector Expressing Pasteurella multocida OmpH Gene

Abstract

Duck enteritis virus and Pasteurella multocida are major duck pathogens that induce duck plague and fowl cholera, respectively, in ducks and other waterfowl populations, leading to high levels of morbidity and mortality. Immunization with live attenuated DEV vaccine containing P. multocida outer membrane protein H (OmpH) can provide the most effective protection against these two infectious diseases in ducks. We have recently reported the construction of recombinant DEV expressing P. multocida ompH gene using the CRISPR/Cas9 gene editing strategy with the goal of using it as a bivalent vaccine that can simultaneously protect against both infections. Here we describe the findings of our investigation into the systemic immune responses, potency and clinical protection induced by the two recombinant DEV-ompH vaccine constructs, where one copy each of the ompH gene was inserted into the DEV genome at the UL55-LORF11 and UL44-44.5 intergenic regions, respectively. Our study demonstrated that the insertion of the ompH gene exerted no adverse effect on the DEV parental virus. Moreover, ducklings immunized with the rDEV-ompH-UL55 and rDEV-ompH-UL44 vaccines induced promising levels of P. multocida OmpH-specific as well as DEV-specific antibodies and were completely protected from both diseases. Analysis of the humoral and cellular immunity confirmed the immunogenicity of both recombinant vaccines, which provided strong immune responses against DEV and P. multocida. This study not only provides insights into understanding the immune responses of ducks to recombinant DEV-ompH vaccines but also demonstrates the potential for simultaneous prevention of viral and bacterial infections using viral vectors expressing bacterial immunogens.

Pathogenicity studies and molecular characterization of DPV infection in ducklings

“…The structure of the LORF11 gene of the SD423 strain was similar to that of the Chinese SD and LH2011 strains, with an 861 bp non-coding region in the middle dividing LORF11 into two coding regions ( Apinda et al, 2022 ), LORF11-A and LORF11-B. The LORF11 gene of European strong strain 2085 and Indian strong strain DP-AS-Km-19 had a deletion of 1,171 bp after 493 bp, resulting in a portion of the gene at both the 5′ and 3′ ends that was highly homologous to SD423 LORF11-A and SD423 LORF11-B, respectively; The LORF11 gene of attenuated duck enteritis virus K p63 has a 647 bp homologous portion at the 5′ end, followed by a deletion of the 3516 bp gene, and then a 178 bp homologous portion.…”

Development and evaluation of a chicken embryo fibroblast cell culture based live attenuated Indian strain duck plague vaccine

“…Then, RPMI-1640 growth medium (100 μL) with DEV (10 4 TCID 50 ) was added to the wells in triplicates for assessment of antigen-specific proliferative response (Apinda et al. 2022 ). Concanavalin A (Con-A, Sigma-Aldrich) @ 20 μg/mL in RPMI-1640 as the positive control and plain growth medium (without antigen or Con-A) as negative control were also taken in triplicate wells.…”

Current Status of Poultry Recombinant Virus Vector Vaccine Development

“…More importantly, DEV-attenuated live vaccines can rapidly induce protective immunity within several hours, and their efficacy is not affected by maternal antibodies [ 161 ]. These advantages make it gradually become a hotspot of vector vaccine research, which has been frequently reported in recent years, including being used as viral vectors to express the P. multocida outer membrane protein H (OmpH) [ 162 ], F protein of NDV [ 163 ], the hemagglutinin genes of H5 and H7 influenza viruses [ 164 ], and P1 and 3C protein of duck hepatitis A virus 3 [ 165 ]. All these recombinants had effective immune protection against specific pathogens.…”