Peptides with 16R in S2 protein showed broad reactions with sera against different types of infectious bronchitis viruses

Revealing Novel-Strain-Specific and Shared Epitopes of Infectious Bronchitis Virus Spike Glycoprotein Using Chemical Linkage of Peptides onto Scaffolds Precision Epitope Mapping

The avian coronavirus, infectious bronchitis virus (IBV), is an economically important infectious disease affecting chickens, with a diverse range of serotypes found globally. The major surface protein, spike (S), has high diversity between serotypes, and amino acid differences in the S1 sub-unit are thought to be responsible for poor cross-protection afforded by vaccination. Here, we attempt to address this, by using epitope mapping technology to identify shared and serotype-specific immunogenic epitopes of the S glycoprotein of three major circulating strains of IBV, M41, QX, and 4/91, via CLIPS peptide arrays based on peptides from the S1 sub-units. The arrays were screened with sera from chickens immunised with recombinant IBV, based on Beau-R backbone expressing heterologous S, generated in two independent vaccination/challenge trials. The screening of sera from rIBV vaccination experiments led to the identification of 52 immunogenic epitopes on the S1 of M41, QX, and 4/91. The epitopes were assigned into six overlapping epitope binding regions. Based on accessibility and location in the hypervariable regions of S, three sequences, 25YVYYYQSAFRPPNGWHLQGGAYAVVNSTN54, 67TVGVIKDVYNQSVASI82, and 83AMTVPPAGMSWSVS96, were selected for further investigation, and synthetic peptide mimics were recognised by polyclonal sera. These epitopes may have the potential to contribute towards a broader cross-protective IBV vaccine.

A novel S2-derived peptide-based ELISA for broad detection of antibody against infectious bronchitis virus

Avian infectious bronchitis (IB) is a highly contagious disease caused by infectious bronchitis virus (IBV). Vaccination is an effective approach for controlling IBV. Therefore, reliable immune monitoring for IB is critical for poultry. In this study, a novel peptide derived from S2 protein was used to develop an enzyme-linked immunosorbent assay (ELISA) for the detection of broadly cross-reactive antibodies against IBV. The peptide-based ELISA (pELISA) showed good specificity and sensitivity in detecting IBV antibodies against different serotypes. A semilogarithmic regression method for determining IBV antibody titers was also established. Antibody titers detected by pELISA and calculated with this equation were statistically similar to those evaluated by indirect fluorescence assay (IFA). Moreover, the comparison analysis showed a 96.07% compatibility between the pELISA and IDEXX ELISA. All these data demonstrate that the pELISA generated here can be as a rapid and reliable serological surveillance tool for monitoring IBV infection or vaccination.

Preparation of the RIPK3 Polyclonal Antibody and Its Application in Immunoassays of Nephropathogenic Infectious Bronchitis Virus-Infected Chickens

Receptor interacting protein kinase 3 (RIPK3) is a vital serine/threonine kinase in regulating the programmed destruction of infected cells to defend against RNA viruses. Although the role of RIPK3 in viruses in mice is well characterized, it remains unclear where in nephropathogenic infectious bronchitis virus (NIBV) in chickens. Here, we use a self-prepared polyclonal antibody to clarify the abundance of RIPK3 in tissues and define the contributions of RIPK3 in tissue damage caused by NIBV infection in chickens. Western blot analyses showed that RIPK3 polyclonal antibody can specifically recognize RIPK3 in the vital tissues of Hy-Line brown chicks and RIPK3 protein is abundantly expressed in the liver and kidney. Moreover, NIBV significantly upregulated the expression levels of RIPK3 in the trachea and kidney of chicks in a time-dependent manner. In addition, the activation of necroptosis in response to NIBV infection was demonstrated by the coimmunoprecipitation (CoIP) experiments through RIPK3 in the necrosome, which phosphorylates its downstream mixed-spectrum kinase structural domain-like protein (MLKL). Our findings offered preliminary insights into the key role of RIPK3 protein in studying the underlying mechanism of organ failure caused by NIBV infection.

Phylogenetic and Spatiotemporal Analyses of the Complete Genome Sequences of Avian Coronavirus Infectious Bronchitis Virus in China During 1985-2020: Revealing Coexistence of Multiple Transmission Chains and the Origin of LX4-Type Virus

Infectious bronchitis (IB) virus (IBV) causes considerable economic losses to poultry production. The data on transmission dynamics of IBV in China are limited. The complete genome sequences of 212 IBV isolates in China during 1985–2020 were analyzed as well as the characteristics of the phylogenetic tree, recombination events, dN/dS ratios, temporal dynamics, and phylogeographic relationships. The LX4 type (GI-19) was found to have the highest dN/dS ratios and has been the most dominant genotype since 1999, and the Taiwan-I type (GI-7) and New type (GVI-1) showed an increasing trend. A total of 59 recombinants were identified, multiple recombination events between the field and vaccine strains were found in 24 isolates, and the 4/91-type (GI-13) isolates were found to be more prone to being involved in the recombination. Bayesian phylogeographic analyses indicated that the Chinese IBVs originated from Liaoning province in the early 1900s. The LX4-type viruses were traced back to Liaoning province in the late 1950s and had multiple transmission routes in China and two major transmission routes in the world. Viral phylogeography identified three spread regions for IBVs (including LX4 type) in China: Northeastern China (Heilongjiang, Liaoning, and Jilin), north and central China (Beijing, Hebei, Shanxi, Shandong, and Jiangsu), and Southern China (Guangxi and Guangdong). Shandong has been the epidemiological center of IBVs (including LX4 type) in China. Overall, our study highlighted the reasons why the LX4-type viruses had become the dominant genotype and its origin and transmission routes, providing more targeted strategies for the prevention and control of IB in China.

The identification of a B-cell epitope in bovine viral diarrhea virus (BVDV) core protein based on a mimotope obtained from a phage-displayed peptide library

Bovine pestivirus A and B, previously known as bovine viral diarrhea virus (BVDV)-1 and 2, respectively, are important pathogens of cattle worldwide, which causes significant economic losses. B-cell epitopes in BVDV glycoprotein E2 and nonstructural protein NS2/3 have been extensively identified. In this study, we screened a 12-mer phage display peptide library using commercial goat anti-BVDV serum, and identified a mimotope "LTPHKHHKHLHA" referred to as P3. With sequence alignment, a putative B-cell epitope "77ESRKKLEKALLA88" termed as P3-BVDV1/2 residing in BVDV core protein was identified. The synthesized peptides of both P3 and P3-BVDV1/2 show strong reactivity with BVDV serum in immune blot assay. Immunization of mice with these individual peptides leads to the production of antibody that cannot neutralize virus infectivity. Thus for the first time we identified a B-cell epitope, "77ESRKKLEKALLA88", in BVDV core protein. Interestingly, the epitope was highly conserved in Pestivirus A, B, C, D, as well as emerging Pestivirus E and I, but highly variable in Pestiviruses H, G, F, and J, as well as unclassified Pestivirus originated from non-ruminant animals. Whether this putative B-cell epitope is implicated in pestivirus pathogenesis or evolution needs further investigations once large numbers of isolates are available in the future.

Peptide enzyme-linked immunosorbent assay (pELISA) as a possible alternative to the neutralization test for evaluating the immune response to IBV vaccine

BACKGROUND

Infectious bronchitis virus (IBV), a coronavirus, is one of the most important poultry pathogens worldwide due to its multiple serotypes and poor cross-protection. Vaccination plays a vital role in controlling the disease. The efficacy of vaccination in chicken flocks can be evaluated by detecting neutralizing antibodies with the neutralization test. However there are no simple and rapid methods for detecting the neutralizing antibodies.

RESULTS

In this study, a peptide enzyme-linked immunosorbent assay (pELISA) as a possible alternative to the neutralization test for evaluating the immune response to IBV vaccine was developed. The pELISA could indirect evaluate neutralizing antibody titers against different types of IBV in all tested sera. The titers measured with the pELISA had a coefficient of 0.83 for neutralizing antibody titers.

CONCLUSIONS

The pELISA could detect antibodies against different types of IBV in all tested sera. The pELISA has the potential to evaluate samples for IBV-specific neutralizing antibodies and surveillance the infection of IBV.

A Peptide-Based Enzyme-Linked Immunosorbent Assay for Detecting Antibodies Against Avian Infectious Bronchitis Virus

Infectious bronchitis virus (IBV) causes substantial loss to the poultry industry despite extensive vaccination. Assessing the antibody response is important for the development and evaluation of effective vaccines. We have developed an enzyme-linked immunosorbent assay (ELISA) for the detection of IBV-specific antibodies, using a synthetic peptide based on a conserved sequence in the IBV spike protein. This peptide-based ELISA (pELISA) specifically detects antibodies to different genotypes of IBV but not antibodies against other common chicken viruses. This assay could detect IBV-specific antibody response on as early as day 7 postinfection. In the testing with field serum samples collected from chickens administered with IBV vaccines, the sensitivity, specificity, and accuracy of pELISA were 98.30, 94.12, and 98.8%, respectively, relative to indirect immunofluorescence assay. Our data demonstrate that the pELISA is of value for the detection of IBV antibody and the evaluation of IBV vaccines.

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

Infectious bronchitis (IB) and Newcastle disease (ND) are two important diseases of poultry and have remained a threat to the development of the poultry industry in many parts of the world. The immunology of avian has been well studied and numerous vaccines have been developed against the two viruses. Most of these vaccines are either inactivated vaccines or live attenuated vaccines. Inactivated vaccines induce weak cellular immune responses and require priming with live or other types of vaccines. Advanced technology has been used to produce several types of vaccines that can initiate prime immune responses. However, as a result of rapid genetic variations, the control of these two viral infections through vaccination has remained a challenge. Using various strategies such as combination of live attenuated and inactivated vaccines, development of IB/ND vaccines, use of DNA vaccines and transgenic plant vaccines, the problem is being surmounted. It is hoped that with increasing understanding of the immunological mechanisms in birds that are used in fighting these viruses, a more successful control of the diseases will be achieved. This will go a long way in contributing to global food security and the economic development of many developing countries, given the role of poultry in the attainment of these goals.