Characterisation of M2e Antigenicity using anti-M2 Monoclonal Antibody and anti-M2e Polyclonal Antibodies

Matrix 2 ectodomain (M2e) protein is a potential antigen for detection of influenza A virus infection in vaccinated poultry (DIVA test). However the M2e antigenicity and immune response it induces in either humans or animals are poorly understood. Seventeen M2e peptides and sixteen recombinant M2e (rM2e) proteins with amino acid (aa) changes introduced at position 10, 11, 12, 13 14, 16, 18 and 20 were compared by western blot (WB) and enzyme-linked immunosorbent assay (ELISA) using mouse anti-M2 monoclonal antibody (mAb) 14C2, and anti-M2e peptide chicken and rabbit polyclonal antibody (pAb). The mAb 14C had the best discriminating power and indicated that all six positions contributed to the M2e antigenicity. Position 11 was the important immunodominant and affected Mab14C binding to a greatest degree. Changes in the adjacent position 14, 16 and 18 also influenced the binding, and it detected regardless of the method (WB or ELISA), or the antigen used (M2e peptide or rM2e). For chicken pAb and rabbit pAb, the immunodominant aa was position 10 and the antibody reaction was not affected by aa change at 11. The binding of rabbit pAb was also affected by changes at 14 and 16, which confirm the contribution of these positions to the M2e antigenicity. Position 10 was the only important position for the binding of chicken pAb to M2e. Overall, the study showed that the M2e antigenic sites are located between residues 10 – 18 and that aa changes at position 10, 11, 12, 14, 16 and 18 may all affect the antibody binding within the M2e protein

Developing Farm-Level Post-vaccination Sero-Monitoring Systems for H5N1 Highly Pathogenic Avian Influenza in an Endemically Infected Country

Whilst the serological responses of poultry following vaccination against highly pathogenic avian influenza H5N1 has been extensively investigated under laboratory conditions, there have been fewer studies conducted in the field. This applies particularly to the endemically infected countries routinely practicing vaccination, where the combination of multiple circulating clades and/or the use of vaccines with different seed strains makes the design and interpretation of field studies especially problematic. To address this for the particular situation of layer hens in the small to medium commercial sector in Indonesia, we developed a sampling regime before and after the vaccination given to point-of-lay pullets, and assessed serological response with a panel of test antigens. This confirmed that high titres were induced in those birds vaccinated with locally produced homologous H5N1 vaccines administered two or more times, but in flocks using imported heterologous H5N2 vaccines median titres were significantly lower, and unlikely to provide protection throughout the production cycle, without additional vaccination. Comparing the HI responses against the panel of antigens enabled the detection of the flock's exposure to different vaccine antigens, and made possible the detection of mislabelled vaccine seed strains. Furthermore, we show that test antigens need not be exactly matched to assess sero-protection in well vaccinated birds. Finally our study suggests that the POL vaccination serves as a useful reference point for following cohorts of layers throughout their production cycle, and thus enabling robust vaccination field effectiveness studies

Epitope mapping of avian influenza m2e protein: different species recognise various epitopes

Published: June 30, 2016A common approach for developing diagnostic tests for influenza virus detection is the use of mouse or rabbit monoclonal and/or polyclonal antibodies against a target antigen of the virus. However, comparative mapping of the target antigen using antibodies from different animal sources has not been evaluated before. This is important because identification of antigenic determinants of the target antigen in different species plays a central role to ensure the efficiency of a diagnostic test, such as competitive ELISA or immunohistochemistry-based tests. Interest in the matrix 2 ectodomain (M2e) protein of avian influenza virus (AIV) as a candidate for a universal vaccine and also as a marker for detection of virus infection in vaccinated animals (DIVA) is the rationale for the selection of this protein for comparative mapping evaluation. This study aimed to map the epitopes of the M2e protein of avian influenza virus H5N1 using chicken, mouse and rabbit monoclonal or monospecific antibodies. Our findings revealed that rabbit antibodies (rAbs) recognized epitope 6EVETPTRN13 of the M2e, located at the N-terminal of the protein, while mouse (mAb) and chicken antibodies (cAbs) recognized epitope 10PTRNEWECK18, located at the centre region of the protein. The findings highlighted the difference between the M2e antigenic determinants recognized by different species that emphasized the importance of comparative mapping of antibody reactivity from different animals to the same antigen, especially in the case of multi-host infectious agents such as influenza. The findings are of importance for antigenic mapping, as well as diagnostic test and vaccine development.Noor Haliza Hasan, Esmaeil Ebrahimie, Jagoda Ignjatovic, Simson Tarigan, Anne Peaston, Farhid Hemmatzade

Purification of neuraminidase from Influenza virus subtype H5N1

Influenza-virus neuraminidase plays vital role in the survival of the organisms. Vaccination of animals with this glycoprotein confers immune responses so that enable it to protect the animals from incoming infection. Supplementation of conventional vaccines with this glycoprotein increases the protection and longevity of the vaccine. Purified neuraminidase can also be used to develop serological tests for differentiation of serologically positive animals due to infection or to vaccination. In this study purification of neuraminidase from influenza virus subtype H5N1 was described. Triton x-100 and Octyl β-D-glucopyranoside were used to extract and diluted the glycoprotein membrane. The enzymatic activity of the neuraminidase was assayed using a fluorochrome substrate, 4-methylumbelliferyl-a-D-N-acetyl neuraminic acid, which was found to be simple, sensitive and suitable for the purification purpose. The neuraminidase was absorbed selectively on an oxamic-acid agarose column. The purity of neuraminidase eluted from this affinity column was high. A higher purity of the neuraminidase was obtained by further separation with gel filtration on Superdex-200. The purified neuraminidase was enzymatically active and did not contain any detectable haemagglutinin, either by haemagglutination assay or by monospecific antibodies raised against H5N1 hemagglutinin.  The purified neuraminidase was recognized strongly by antibodies raised against an internal but only weakly by that against C-terminal regions of the neuraminidase protein of H5N1-influenza virus. The purified neuraminidase was in tetrameric forms but dissociated into monomeric form on reducing condition, or mostly dimeric form on non-reducing SDS-PAGE. Key Words: Neuraminidase, Influenza, H5N1, Methylumbelliferyl, Oxamic-aci

Purification of neuraminidase from Influenza virus subtype H5N1

Influenza-virus neuraminidase plays vital role in the survival of the organisms. Vaccination of animals with this glycoprotein confers immune responses so that enable it to protect the animals from incoming infection. Supplementation of conventional vaccines with this glycoprotein increases the protection and longevity of the vaccine. Purified neuraminidase can also be used to develop serological tests for differentiation of serologically positive animals due to infection or to vaccination. In this study purification of neuraminidase from influenza virus subtype H5N1 was described. Triton x-100 and Octyl β-D-glucopyranoside were used to extract and diluted the glycoprotein membrane. The enzymatic activity of the neuraminidase was assayed using a fluorochrome substrate, 4-methylumbelliferyl-a-D-N-acetyl neuraminic acid, which was found to be simple, sensitive and suitable for the purification purpose. The neuraminidase was absorbed selectively on an oxamic-acid agarose column. The purity of neuraminidase eluted from this affinity column was high. A higher purity of the neuraminidase was obtained by further separation with gel filtration on Superdex-200. The purified neuraminidase was enzymatically active and did not contain any detectable haemagglutinin, either by haemagglutination assay or by monospecific antibodies raised against H5N1 hemagglutinin. The purified neuraminidase was recognized strongly by antibodies raised against an internal but only weakly by that against C-terminal regions of the neuraminidase protein of H5N1-influenza virus. The purified neuraminidase was in tetrameric forms but dissociated into monomeric form on reducing condition, or mostly dimeric form on non-reducing SDS-PAGE

Infectious Bronchitis Viruses with a Novel Genomic Organization▿

A number of novel infectious bronchitis viruses (IBVs) were previously identified in commercial poultry in Australia, where they caused significant economic losses. Since there has been only limited characterization of these viruses, we investigated the genomic and phenotypic differences between these novel IBVs and other, classical IBVs. The 3′ 7.5 kb of the genomes of 17 Australian IBV strains were sequenced, and growth properties of 6 of the strains were compared. Comparison of sequences of the genes coding for structural and nonstructural proteins revealed the existence of two IBV genotypes: classical and novel. The genomic organization of the classical IBVs was typical of those of other group III coronaviruses: 5′-Pol-S-3a-3b-E-M-5a-5b-N-untranslated region (UTR)-3′. However, the novel IBV genotype lacked either all or most of the genes coding for nonstructural proteins at the 3′ end of the genome and had a unique open reading frame, X1. The gene order was either 5′-Pol-S-X1-E-M-N-UTR-3′ or 5′-Pol-S-X1-E-M-5b-N-UTR-3′. Phenotypically, novel and classical IBVs also differed; novel IBVs grew at a slower rate and reached lower titers in vitro and in vivo and were markedly less immunogenic in chicks. Although the novel IBVs induced histopathological lesions in the tracheas of infected chicks that were comparable to those induced by classical strains, they did not induce lesions in the kidneys. This study has demonstrated for the first time the existence of a naturally occurring IBV genotype devoid of some of the genes coding for nonstructural proteins and has also indicated that all of the accessory genes are dispensable for the growth of IBV and that such viruses are able to cause clinical disease and economic loss. The phylogenic differences between these novel IBVs and other avian coronaviruses suggest a reservoir host distinct from domestic poultry

Antibody types and animals used for the generation of antibodies either by H5N1 virus challenge, or KLH-M2e_2-19 peptide immunization.

<p>Antibody types and animals used for the generation of antibodies either by H5N1 virus challenge, or KLH-M2e_2-19 peptide immunization.</p

Summary of epitopes recognized on influenza A virus M2e protein by different antibodies.

<p>Summary of epitopes recognized on influenza A virus M2e protein by different antibodies.</p

Hydrophobicity plot of M2e protein sequence (residue 2 to 24) based on Kyte & Doolittle scale mean of hydrophobicity profile in BioEdit.

<p>Hydrophobicity plot of M2e protein sequence (residue 2 to 24) based on Kyte & Doolittle scale mean of hydrophobicity profile in BioEdit.</p