| Chicken and duck show large divergence in susceptibility to H5N1highlypathogenic avian influenza virus (HPAIV), since the spread of avian influenza virus tohuman and the poultry have brought great harm. Various studies have been focusingon impact of the continuing evolution of avian influenza virus and host adaption to it.However, few studies explored the mechanism underlining the divergentsusceptibility of the two bird species. In this study, we sought to investigate thevariable region of the immunoglobulin of HPAIV-infected chicken and duck tounderstand the antibody repertoires of the two species and to find the recombinationtrends of HPAIV-specific antibodies. It will lay foundation for prevention of thedisease and the development of efficient antibody.In this study, immunoglobulin light chain variable region (IgLV) of SPF chickensand avian influenza virus infected (AIV) chickens was amplified using5’RACE.Respectively85and73IgLV sequences were analyzed for chicken SPF chicken andHPAIV-infected chicken. Two groups of IgLV sequences are derived from the samegene family. The homology between the sequences is greater than80%. Poultryrecombinant IgLV depends on the gene conversion mechanism. Characteristics werelisted as follows form calculating usage between germLine (VL germLine) and25pseudogenes: SPF group and AIV-infected group both mostly used psi-v5. SPF groupused more psi-v4and psi-v8. And AIV-infected group used more psi-v14and psi-v10.SPF group did not use the psi-v19; AIV-infected group did not use the psi-v9andpsi-v24. It was speculated that psi-v14and psi-v10were preferred under infectionstatus. It llustrated the usage of psi-v19may be the characteristics sequence of AIVspecific antibody.SPF group got the inserted sequences in the amino acid sequences of CDR1region,but AIV-infected group were conservative; there were no significant changes betweenthem in CDR2region. It seemed similar in the first half of the CDR3region.AIV-infected group shows amino acid deletion in position8-11in a majority of thecomponents, and the SPF group had low levels of various amino acids in this position evenly distributed. Length of CDR3amino acids in SPF group were between8-14,AIV group distributed between1-15. On the basis of the sequence usage, the tertiarystructures of the protein were predicted under the AIV infection.The same method was taken to obtain47IgLV the full-length gene of SPF ducksand32of AIV-infected ducks. Sequence homology was greater than70%. Twogroups of sequences with different preferences, non-infection group preferences usingthe tenth region sequences, AIV-infection group preferences using the second regionsequences. The second region sequences may be the special sequence for AIV specificantibody of duck IgLV. It was obtained21pseudogenes by analysising of duckgenome sequence, and this will fill the blank of the research of duck IgLVpseudogene.AIV-infected and non-infected duck difference structures of amino acids wereanalysised. Conservative amino acid compositions were distributed in the AIV groupin specific sites:3Y in the CDR2region;8Y,9V,10G and12V in CDR3region. Thespecificity of AIV group consisting of specific amino acid at specific sites is differentfrom SPF group: for example,12N in CDR1,2N and4T in CDR2and4E and5G inCDR3. CDR3s of infected duck were composed of10or11amino acids. And CDR3slength of SPF duck ranged grom6to12amino acids. The shortest and longest CDR3were both found in SPF duck. The tertiary structures of the protein were predicted inAIV-infected and non-infected cases. These may be the amino acid composition ofspecific antibody of AIV-infection group. According to the predicted amino acidsequence of protein, the study found the hydrophobic amino acid was reduced afterinfection, and the hydrophilic amino acid were the main component; increased aminoacid such as tyrosine (Y), serine (S), glycine (G), is beneficial for antibody affinitymaturation, which is characteristic of specific antibody of amino acids after AIVinfection. |
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