A Recombinant La Sota Vaccine Strain Expressing Multiple Epitopes of Infectious Bronchitis Virus (IBV) Protects Specific Pathogen-Free (SPF) Chickens against IBV and NDV Challenges

Abstract

Infectious bronchitis (IB) and Newcastle disease (ND) are two major infectious diseases that are a threat to the domestic poultry industry. In this study, we successfully generated a recombinant LaSota candidate vaccine strain, rNDV-IBV-T/B, which expresses a short, synthetic, previously identified IBV S1 multi-epitope cassette using the reverse genetic system. The recombinant virus was propagated in nine-day-old embryonated chicken eggs for 20 passages and genetic stability was confirmed by whole genome DNA sequencing. The recombinant virus had a hemagglutination (HA) titer of 2 10 , mean death time (MDT) of 118 hours, and intracerebral pathogenicity index (ICPI) of 0.05. None of these were significantly different from the parental Newcastle disease virus (NDV) LaSota strain (p > 0.05). Vaccination of white leghorn chickens at one day of age with 10 6 EID 50 rNDV-IBV-T/B provided 90% protection against virulent IBV M41 challenge at three weeks of age, which was significantly higher than the protection of the control group vaccinated with phosphate-buffered saline (PBS) (p < 0.05). The ciliostasis scores of rNDV-IBV-T/B-vaccinated and LaSota-vaccinated groups were 4.2 and 37.6, respectively, which indicated that rNDV-IBV-T/B vaccination reduced the pathogenicity of IBV toward the trachea. Furthermore, real-time RT-PCR assay showed that the rNDV-IBV-T/B vaccination resulted in low levels of viral load (647.80 ± 49.65 RNA copies) in the trachea four days post-challenge, which is significantly lower than groups vaccinated with PBS (8591.25 ± 311.10 RNA copies) or LaSota (7742.60 ± 298.50 RNA copies) (p < 0.05). Meanwhile, the same dose of rNDV-IBV-T/B vaccination provided complete protection against velogenic NDV F48E9 challenge. These results demonstrate that the rNDV-IBV-T/B strain is a promising vaccine candidate to control both IB and ND simultaneously. Furthermore, epitope-based live vector vaccines provide an alternative strategy for the development of cost-effective and, broadly, cross-protective vaccines.

Development of a Recombinant Thermostable Newcastle Disease Virus (NDV) Vaccine Express Infectious Bronchitis Virus (IBV) Multiple Epitopes for Protecting against IBV and NDV Challenges

“…Therefore, a novel vaccine should consider protection against challenges by different serotype IBVs. Our previous studies demonstrated that DNA vaccine or recombinant NDVs expressing the IBV multiple epitope cassette S-T/B, consisting of three pieces of B cell neutralizing epitopes and four pieces of BF2-restricted T cell epitopes, offer potency against homologous and heterologous IBV strain challenges [ 24 , 26 ]. However, the main shortcoming of NDV-vectored bivalent vaccines is that their thermolabile and low temperature characteristics might not be properly maintained during mass vaccination.…”

“…The antigenicity for expressing the multiple epitope cassette S-T/B of the rLS-T-HN-T/B strain was analyzed by Western blotting according to a previously reported method [ 24 ].…”

“…During the past two decades, NDV has been proven to be a suitable virus vector for expressing proper exogenous antigens against a variety of pathogens in poultry [ 19 , 20 , 21 , 22 , 23 ]. In a previous study, we developed a recombinant NDV-vector vaccine (rNDV-IBV-T/B) harboring the IBV multiple epitope cassette (S-T/B), which can effectively protect chickens against lethal doses of NDV F48E9 and IBV M41 strain challenges [ 24 ]. The S-T/B multiple epitope cassette consists of three neutralizing epitope domains located at the S1 protein 24–61, 132–149, and 291–398 amino acids (AAs) of the IBV Australian T strain (Genbank AAV52771.1) and the four chicken BF2 (major histocompatibility complex class I)-restricted Cytotoxic T lymphocyte (CTL) epitopes located at the S1 protein 413–421 and 517–525 AAs of the QX-like IBV SH1208 strain (Genbank ASA45778.1) and the 45–52 and 413–421 AAs of the Holte strain (Genbank AAA74379.1) [ 25 , 26 ].…”

Towards Improved Use of Vaccination in the Control of Infectious Bronchitis and Newcastle Disease in Poultry: Understanding the Immunological Mechanisms

“…Some other studies reported a recombinant NDV expressing IBV S protein generated using reverse genetics technology to fully protect from challenge with virulent NDV and IBV [170,171]. Similarly, an rNDV-IBV-T/B multiple-epitope NDV vectored vaccine developed using reverse genetics, protected against IBV and NDV [172]. More so, R-H120-HN/5a an IBV/NDV recombinant vaccine developed by reverse genetics reportedly induced humoral immune response and provided protection against challenge with virulent IBV and NDV.…”

Infectious Bronchitis Virus Evolution, Diagnosis and Control

“…Many of these genetic constructs [ 100 , 101 ] are based on a Beaudette strain (GI-1) backbone, which lacks of pathogenicity and would prevent residual effects of the attenuation process, others focus on the deletion of pathogenicity-associated genes [ 96 ], obtaining attenuation without the loss of protection. Recombinant vaccines have been produced also by cloning IBV proteins into the backbone of other viruses (Fowl Adenovirus, FAdV [ 102 , 103 ]; Newcastle disease virus, NDV [ 104 , 105 ]; avian Metapneumovirus, aMPV [ 106 ]), achieving a variable degree of protection. However, individual administration was still required for these vaccines, thus limiting their practicability.…”