Characterization of a monoclonal antibody against the hemagglutinin stem of H7N9 subtype avian influenza virus / 生物工程学报

The conserved hemagglutinin (HA) stem region of avian influenza virus (AIV) is an important target for designing broad-spectrum vaccines, therapeutic antibodies and diagnostic reagents. Previously, we obtained a monoclonal antibody (mAb) (5D3-1B5) which was reactive with the HA stem epitope (aa 428-452) of H7N9 subtype AIV. To systematically characterize the mAb, we determined the antibody titers, including the HA-binding IgG, hemagglutination-inhibition (HI) and virus neutralizing (VN) titers. In addition, the antigenic epitope recognized by the antibody as well as the sequence and structure of the antibody variable region (VR) were also determined. Moreover, we evaluated the cross-reactivity of the antibody with influenza virus strains of different subtypes. The results showed that the 5D3-1B5 antibody had undetectable HI and VN activities against H7N9 virus, whereas it exhibited strong reactivity with the HA protein. Using the peptide-based enzyme-linked immunosorbent assay and biopanning with a phage-displayed random peptide library, a motif with the core sequence (431W-433Y-437L) in the C-helix domain in the HA stem was identified as the epitope recognized by 5D3-1B5. Moreover, the mAb failed to react with the mutant H7N9 virus which contains mutations in the epitope. The VR of the antibody was sequenced and the complementarity determining regions in the VR of the light and heavy chains were determined. Structural modeling and molecular docking analysis of the VR verified specific binding between the antibody and the C-helix domain of the HA stem. Notably, 5D3-1B5 showed a broad cross-reactivity with influenza virus strains of different subtypes belonging to groups 1 and 2. In conclusion, 5D3-1B5 antibody is a promising candidate in terms of the development of broad-spectrum virus diagnostic reagents and therapeutic antibodies. Our findings also provided new information for understanding the epitope characteristics of the HA protein of H7N9 subtype AIV.

Identification, sequence analysis, and infectivity of H9N2 avian influenza viruses isolated from geese

The subtype H9N2 avian influenza virus greatly threatens the Chinese poultry industry, even with annual vaccination. Waterfowl can be asymptomatically infected with the H9N2 virus. In this study, three H9N2 virus strains, designated A/Goose/Jiangsu/YZ527/2011 (H9N2, Gs/JS/YZ527/11), A/Goose/Jiangsu/SQ119/2012 (H9N2, Gs/JS/SQ119/12), and A/Goose/Jiangsu/JD564/2012 (H9N2, Gs/JS/JD564/12), were isolated from domestic geese. Molecular characterization of the three isolates showed that the Gs/JS/YZ527/11 virus is a double-reassortant virus, combining genes of A/Quail/Hong Kong/G1/97 (H9N2, G1/97)-like and A/Chicken/Shanghai/F/98 (H9N2, F/98)-like; the Gs/JS/SQ119/12 virus is a triple-reassortant virus combining genes of G1/97-like, F/98-like, and A/Duck/Shantou/163/2004 (H9N2, ST/163/04)-like. The sequences of Gs/JS/JD564/12 share high homology with those of the F/98 virus, except for the neuraminidase gene, whereas the internal genes of Gs/JS/YZ527/11 and Gs/JS/SQ119/12 are closely related to those of the H7N9 viruses. An infectivity analysis of the three isolates showed that Gs/JS/SQ119/12 and Gs/JS/YZ527/11 replicated well, with seroconversion, in geese and chickens, the Gs/JS/JD564/12 did not infect well in geese or chickens, and the F/98 virus only infected chickens, with seroconversion. Emergence of these new reassortant H9N2 avian influenza viruses indicates that these viruses can infect both chicken and goose and can produce different types of lesions in each species.

Proteomic analysis of chicken peripheral blood mononuclear cells after infection by Newcastle disease virus

Characteristic clinical manifestations of Newcastle disease include leukopenia and immunosuppression. Peripheral blood mononuclear cells (PBMCs) are the main targets of Newcastle disease virus (NDV) infection. To survey changes in proteomic expression in chicken PBMCs following NDV infection, PBMC proteins from 30 chickens were separated using two-dimensional electrophoresis (2-DE) and subjected to mass spectrometry analysis. Quantitative intensity analysis showed that the expression of 78 proteins increased more than two-fold. Thirty-five proteins exhibited consistent changes in expression and 13 were identified as unique proteins by matrix assisted laser desorption ionization-time of flight mass spectrometer/mass spectrometer including three that were down-regulated and 10 that were up-regulated. These proteins were sorted into five groups based on function: macromolecular biosynthesis, cytoskeleton organization, metabolism, stress responses, and signal transduction. Furthermore, Western blot analysis confirmed the down-regulation of integrin-linked kinase expression and up-regulation of lamin A production. These data provide insight into the in vivo response of target cells to NDV infection at the molecular level. Additionally, results from this study have helped elucidate the molecular pathogenesis of NDV and may facilitate the development of new antiviral therapies as well as innovative diagnostic methods.

Development and Identification of a Live Attenuated Influenza B Virus Vaccine Candidate / 生物化学与生物物理进展

A cold-adapted (ca), temperature sensitive (ts), live attenuated influenza B virus strain B/Ann Arbor/1/66 was chosen for influenza virus rescue research, in which six internal gene segments, PB1, PB2, PA, NP, M, NS, were fully synthesized and nine amino acid substitutions were artificially alter by human intervention. The resultant B/Ann Arbor/1/66 plasmids were named as pAB121-PB1, pAB122-PB2, pAB123-PA, pAB124-HA, pAB125-NP, pAB126-NA, pAB127-M and pAB128-NS, respectively. A recombinant influenza A virus was previously generated entirely from cloned cDNA. An infectious recombinant influenza B virus was generated here, and designated as rMDV-B, by plasmid-based reverse genetics. The rMDV-B virus contained HA and NA genes from an epidemic influenza B vires strain B/Malaysia/2506/2004 in the background of internal genes derived from influenza B virus strain B/Ann Arbor/1/66. HA titer of rMDV-B in MDCK cells and embryonated chicken eggs ranged from 1 : 64 to 1 : 512. The results may allow an effective live influenza B vaccine to be produced from a single master strain, providing a model for the design of future live human influenza vaccines.

Construction and characterization of avian pathogenic Escherichia coli mutants with iro and/or tsh gene mutation / 生物工程学报

Iro system and temperature-sensitive hemagglutinin (Tsh) genes were identified by suppression subtractive hybridization (SSH) and selective capture of transcribed sequences (SCOTS). To get more insights in the distribution and the occurrence of the iroC and tsh genes, we examined 243 avian E. coli strains for the presences of the these genes. Among 243 avian E. coli isolates, iroC gene was present in 84.4% strains (205/243). Of the 205 iroC-positive isolates, iroC gene was found in 184 (89.8%), 18(8.8%) and 3 (1.5%) isolates with high, intermediate and low pathogenicity, respectively. Of the 167 tsh-positive isolates, tsh gene was detected in 146 (87.4%), 21 (12.6%) and 0 (0%) isolates with high, intermediate and low pathogenicity, respectively. Among tsh-positive isolates, 89.5 to 100% of the highly pathogenic isolates of O1, O2 or O78 serogroups had the tsh gene, while 53.3% of the highly pathogenic isolates of non-O1, O2 and O78 serogroups had the tsh gene (P<0.01). Suicide vectors for deletion of the iroBCDEN or tsh genes were constructed as follows. The 715-bp fragments of iroB and 603-bp fragment of the iroN were generated by PCR respectively. Both of these two fragments together with EGFP gene were cloned into pUC18, termed pUC18-iroBNEGFP. A resultant suicide vector containing the iroB-EGFP-iroN fragment was obtained and named pMEG375-iroBNEGFP. Similarly, both of the 685-bp fragment of tshF and the 692-bp fragment of the tshR together with gentamycin gene were cloned into pUC18, resulting in pUC18-tshFRGm. A resultant suicide vector containing the tshF-Gm-tshR fragment was named pMEG375-tshFRGm. Mutant derivatives of strain E037 were generated by allelic replacements and were named E037(Deltairo), E037(Deltatsh) and E037(DeltairoDeltatsh). The 50% lethal dose (LD50) of E037, E037(Deltairo), E037(Deltatsh) and E037(DeltairoDeltatsh) in commercial day-old chickens experimentally inoculated via intratrachea were determined to be 10(5.6), 10(8.4), 10(9.0) and 10(9.5)CFU, respectively. In the chicken challenging model, the mutants were tested to determine the individual role of this system for virulence and persistence in chickens. The result suggested that Iro system and Tsh were important in the pathogenicity of APEC.

Generation of cold-adapted, attenuated reassortant human influenza A virus with eight-plasmid system / 中华微生物学和免疫学杂志

Objective To set up a technical platform of reverse genetics based on the 8 plasmid.virus rescue system of cold-adapted influenza virus strain. Methods The cold-adapted, temperature sensitive, live attenuated influenza virus strain A/AnnArbor/6/60(H2N2)was chosen as the master donor virus(MDV)for rescue research,and its six internal gene fragments PB2,PB1,PA,NP,M and NS were artificially synthesized. Meanwhile, five amino acid mutations have been introduced as tags. Six fragments were ligated with modified pAD3000 for the construction of rescue plasmid. Six transcription/expression plasmids(pMDV-A-PB2,pMDV-A-PB1,pMDV-A-PA,pMDV-A-NP,pMDV-A-M,and pMDV-A-NS)were obtained, and their sequences were accurate. Results The reassorted virus named as rMDV-A contains HA and NA gene segments derived from PR8 strain along with six gene segments,PB2,PB1,PA,NP,M and NS,from MDV. The COS-1 cells were co-transfected with eight recombinant plasmids. The results showed that a cold-adapted, attenuated reassortant influenza A virus with hemagglutination activity was rescued successfullv bv"6+2" combination of MDV and PR8, and the allanotoic fluid of the injected eggs gave a posigenes of A/AA/6/60 used as backbone has provided experimental materials for further research on the gene function and novel vaccine candidate of cold-adapted, attenuated human influenza virus.

Construction of Attenuated Influenza Virus Vaccines of Vaccines of-2006-2007 / 生物化学与生物物理进展

Six gene segments,PB1,PB2,PA,NP,M and NS,were fully synthesized which derived from the master donor virus (MDV),cold-adapted(ca),temperature sensitive(ts),live attenuated influenza virus strain A/Ann Arbor/6/60(MDV-A).Meanwhile,five amino acid substitutions (PB1-391E,58lG,661T,PB2-265S,NP-34G) were artificially altered by human intervention.HA and NA fragments derived from the 2006-2007 circulating strain A/New Caledonia/20/99 (H1N1).Eight fragments were ligated with modified pAD3000 for rescue plasmid construction.Eiight transcription/expression plasmids were named as pMDV-A-PB2,pMDV-A-PB1,pMDV-A-PA,pMDV-A-NP,pMDV-A-M,pMDV-A-NS,pMDV-A-HA,pMDV-A-NA,respectively.The COS-l cells were co-transfected with eight plasmids representing 6 internal viral backbone of the strain A/AA/6/60 and two plasmids containing the CDNA of the HA and NA segments of the strain A/New Caledonia/20/99 (H1N1),the results showed that cold-adapted,attenuated reassortant influenza A virus Was rescued successfully.Titers of a reassorted influenza A virus in embryonated chicken eggs mnged from 1:29to l:210.The rescue system of six intemal genes used as backbone opens the way for further research on gene function and neotype vaccine candidate of cold-adapted,live attenuated human influenza virus.

Construction of Attenuated Influenza Virus Vaccines of 2006～2007 / 生物化学与生物物理进展

Six gene segments, PB1, PB2,PA, NP, M and NS, were fully synthesized which derived from the master donor virus(MDV), cold-adapted(ca),temperature sensitive(ts), live attenuated influenza virus strain A/Ann Arbor/6/60(MDV-A). Meanwhile, five amino acid substitutions (PB1-391E, 581G, 661T, PB2-265S, NP-34G) were artificially altered by human intervention. HA and NA fragments derived from the 2006～2007 circulating strain A/New Caledonia/20/99 (H1N1). Eight fragments were ligated with modified pAD3000 for rescue plasmid construction. Eight transcription/expression plasmids were named as pMDV-A-PB2, pMDV-A-PB1, pMDV-A-PA, pMDV-A-NP, pMDV-A-M, pMDV-A-NS, pMDV-A-HA, pMDV-A-NA, respectively. The COS-1 cells were co-transfected with eight plasmids representing 6 internal viral backbone of the strain A/AA/6/60 and two plasmids containing the cDNA of the HA and NA segments of the strain A/New Caledonia/20/99 (H1N1), the results showed that cold-adapted, attenuated reassortant influenza A virus was rescued successfully. Titers of a reassorted influenza A virus in embryonated chicken eggs ranged from 1∶29 to 1∶210. The rescue system of six internal genes used as backbone opens the way for further research on gene function and neotype vaccine candidate of cold-adapted, live attenuated human influenza virus.

Study on CD8~+ T cell epitope expressed by eukaryotic plasmid delivered by attenuated E.coli / 中国免疫学杂志

Objective:To analyze the efficiency of delivery for CD8+ T cell epitope by attenuated E.coli vector.Methods:The recombinant E.coli strain 13A(pG2F),harbouring the eukaryotic expression plasmid pG2F with CD8+ T cell epitope of Ovalbumin (OVA) and green fluorescent protein (GFP) marker at the C-terminal was used to infect into LKb cells,bone marrow dendritic cells (BMDC).The efficiency of presentation for CD8+T cell epitope delivered by recombinant bacteria was analyzed by in vitro antigen presentation assay.C57BL/6 mice were immunized intravenously with 13A(pG2F).Murine IFN-? secreting cells were detected in murine splenocytes by enzyme-linked immunospot assay (ELISPOT).Results:After the infection of LKb cells,BMDC by recombinant bacteria,about 0.3%～4% of cells were GFP positive.The results indicated that attenuated strain 13A could deliver the eukaryotic expression plasmid into mammalian cells.At 2 h post infection,CD8+ T cell epitope was presented on the surface of those LKb,BMDC cells infected by 13A (pG2F) could be recognized by B3Z T hybridoma cells.The presentation efficiency of LKb cells for OVA CD8+ T cell epitope was increased at 48h after infection.Furthermore,the presentation efficiency of BMDC was higher than those of LKb cells under the same condition.The recombinant bacteria 13A(pG2F) could induce cellular immune responses in C57BL/6 mice.Conclusion:Attenuated E.coli can effectively deliver the CD8+ T cell epitope in vitro and in vivo.