Preparation and identification of a broad-spectrum antibody targeting hemagglutinin protein of influenza A virus / 中华微生物学和免疫学杂志

Objective:To prepare and identify a broad-spectrum antibody FHA3 targeting influenza A virus hemagglutinin (HA).Methods:According to the single-chain antibody fragment (scFv) sequence, the heavy chain (VH) and light chain (VL) variable regions of FHA3 were amplified by PCR and a recombinant plasmid pFRT-IgG1κ-FHA3 was constructed by linking the expression vector pFRT-IgG1κ. FHA3 was expressed in the ExpiCHO system and purified by affinity purification. The binding activity of FHA3 to influenza A virus HA was detected by ELISA. The neutralizing activity of FHA3 was detected in vitro by infecting host cells with pseudovirus. Results:SDS-PAGE showed that high-purity FHA3 was obtained. FHA3 could bind to H1N1 HA, H2N2 HA, H3N2 HA, H5N1 HA, H7N9 HA and H9N2 HA in a concentration-dependent manner. FHA3 had good neutralizing activity in vitro that was it could effectively block the invasion of H5N1 and H7N9 pseudoviruses into target cells at a low concentration of 5 μg/ml and H1N1 pseudovirus at 0.012 5 μg/ml. Conclusions:A broad spectrum antibody targeting HA protein of influenza A virus with neutralizing activity in vitro was obtained.

Single B cell sorting-based amplification and functional identification of HIV-1 monoclonal antibody genes / 中华微生物学和免疫学杂志

Objective@#To amplify and identify monoclonal antibody genes from HIV-1-infected patients.@*Methods@#Single cell sorting was used to isolate antigen-specific single B cells. Sequence Identity Matrix and the international ImMunoGeneTics information system were used to analyze antibody variable region genes. Binding abilities were detected by enzyme linked immunosorbent assay. Neutralizing activities were tested by TZM-bl/pseudovirus assay.@*Results@#The heavy and light chain genes of four, seven, and eleven antibodies were amplified and sequenced from three HIV-1-infected patients, respectively. They were derived from various germline genes with flexible CDR3 lengths and somatic mutations. A1 and B3 antibodies bound to HIV-1 clade B, CRF01_AE, and CRF07_BC antigens. The half maximal inhibitory concentration values of A1 and B3 against MW965 virus were 0.04 μg/ml and 37.34 μg/ml.@*Conclusion@#In this study, we acquired a lot of monoclonal antibody genes and two HIV-1 monoclonal binding and neutralizing antibodies, which would provide basic data for further research on monoclonal antibody identification.

Isolation and identification of neutralizing monoclonal antibodies to two Tier 2 viruses in a patient with HIV-1 infection / 中华微生物学和免疫学杂志

Objective To isolate neutralizing monoclonal antibodies to Tier 2 viruses in a Chinese patient with HIV-1 infection. Methods Monoclonal antibodies were isolated using single B cell sorting and monoclonal antibody expression technique. The international ImMunoGeneTics database (IMGT) was used to analyze antibody variable region genes. Antibody binding ability and neutralizing activity were tested by enzyme linked immunosorbent assay and TZM-bl/pseudovirus assay,respectively. Results Two monoclonal antibodies (E11 and H2) that could neutralize two Tier 2 viruses were isolated from the patient with clade B HIV-1 infection. Heavy chains of E11 and H2 were derived from IGHV4-4*08 with a somatic mutation rate of 15.79% and 14.74%,respectively. Light chains were both derived from IGKV3-15*01 with a somatic mutation rate of 8.33% and 7.95%, respectively. E11 and H2 could bind to HIV-1 clade B, CRF01_AE and CRF07_BC viruses. The half maximal inhibitory concentration(IC50) values of E11 and H2 were 18.78 μg/ml and 22.43 μg/ml against 398-F1 virus and 43.35 μg/ml and 39.45 μg/ml against 25710 virus. Conclusion In this study, two neutralizing monoclonal antibodies to two Tier 2 viruses were identified in the patient with HIV-1 infection,which might provide reference for the development of AIDS vaccines.

Preparation and preliminary application of a neutralizing monoclonal antibody against rabies virus / 中华微生物学和免疫学杂志

Objective To prepare a neutralizing monoclonal antibody against rabies virus. Meth-ods BALB/c mice were immunized with the inactivated rabies virus CTN strains on day 0, 7, 14 and 28. Spleen cell samples were collected and then fused with SP2/0 cells to prepare the hybridoma cell line. Posi-tive hybridoma cells that were screened out with RFFIT technique were injected into BALB/c mice intraper-itoneally. Ascites samples were collected from the mice to separate neutralizing monoclonal antibodies. Affin-ity chromatography was used for the purification of neutralizing monoclonal antibodies. Subtype identification and sequencing analysis were performed for further identification. A colloidal gold strip based method for rap-id detection of rabies vaccine was established with the prepared monoclonal antibodies. Results The hybri-doma cell line, CTN-McAb1, was prepared successfully with stable secretion of neutralizing monoclonal anti-bodies against rabies virus. The purity of those antibodies was more than 95% after purification and the sub-type of them was IgG1. The colloidal gold strip for raid detection of rabies vaccine was successful prepared. Conclusion The neutralizing monoclonal antibody against rabies virus was successfully prepared and could be used for preliminary application. This study will be of great significance for the quality control of rabies vaccine.

Develope Monoclonal Antibody against Foot-and-mouth Disease Virus A Type / 中国病毒学·英文版

In order to develop an anti-FMDV A Type monoclonal antibo by (mAb),BABL/c mice were immunized with FMDV A type.Monoclonal antibodies (mAbs) 7B11 and 8H4 against Foot-and-mouth disease virus (FMDV) serotype A were produced by fusing SP2/O myeloma cells with splenocyte from the mouse immunized with A/AV88.The microneutralization titer of the mAbs 7B11 and 8H4 were 1024 and 512,respectively.Both mAbs contain kappa light chains,the mAbs were IgG1.In order to define the mAbs binding epitopes,the reactivity of these mAbs against A Type FMDV,were examined using indirect ELISA,the result showed that both mAbs reacted with A Type FMDV.These mAbs may be used for further vaccine studies,diagnostic methods,prophylaxis,etiological and immunological research on FMDV.Characterization of these ncindicated that prepared anti-FMDV A mAbs had no cross-reactivity with Swine Vesicular Disease (SVD) or FMDV O,Asial and C Type antigens.Their titers in abdomen liquor were 1:5×106 and 1:2×106,respectively.7B11 was found to be of subtype IgG1,8H4 was classified as IgG2b subtype.The mAbs prepared in this study,are specific for detection of FMDV serotype A,and is potentially useful for pen-side diagnosis.

The impact of the modification of 2G12 and 2F5 neutralizing epitopes of the HIY-1 envelope (Env) on its assembly of functional pseudovirus and neutralizing activity / 中华微生物学和免疫学杂志

Objective To study the influence of the modification of the special neutralizing epitopes of the HIV-1 envelope (Env) on its assembly of functional pseudovirus and neutralizing activity. Methods Site-directed mutations were performed using cycling mutagenesis and selection of mutants with Dpn I . With this method, the 2G12 and 2F5 neutralizing epitopes were integrated into Env of subtype BC which was without the two epitopes, then the capability of forming pseudovirus and the neutralizing activity against 2G12 and 2F5 were compared with pre-modified Env. Results The special Env neutralizing epitopes of five HIV pseudovirus (BC02, BC03, BC04, BC05 and BC12) were modified. Among the five pseudovirus, BC04 and BC12 pseudovirus can't be formed after the 2G12 epitope was modified, whilst the BC02, BC03 and BC05 pseudovirus can be formed after the 2G12 and 2F5 epitopes were added, and there was no variation of the pseudovirus titer; On the aspect of neutralizing activity, BG03 pseudovirus against 2G12 and 2F5 was enhanced, BC02 and BC05 pseudovirus against 2F5 was enhanced while which against 2G12 was not changed. Conclusion The modification of 2G12 epitope influences the forming of pseudovirus and the addition of neutralizing epitopes can enhance the neutralizing activity of pseudovirus, which offers new approach for the optimization of HIV immunogen.

"Unconventional" Neutralizing Activity of Antibodies Against HIV / 中国病毒学·英文版

Neutralizing antibodies are recognized to be one of the essential elements of the adaptive immune response that must be induced by an effective vaccine against HIV. However, only a limited number of antibodies have been identified to neutralize a broad range of primary isolates of HIV-1 and attempts to induce such antibodies by immunization were unsuccessful. The difficulties to generate such antibodies are mainly due to intrinsic properties of HIV-1 envelope spikes, such as high sequence diversity, heavy glycosylation, and inducible and transient nature of certain epitopes. In vitro neutralizing antibodies are identified using "conventional" neutralization assay which uses phytohemagglutinin (PHA)-stimulated human PBMCs as target cells. Thus, in essence the assay evaluates HIV-1 replication in CD4+ T cells. Recently, several laboratories including us demonstrated that some monoclonal antibodies and HIV-1-specific polyclonal IgG purified from patient sera, although they do not have neutralizing activity when tested by the "conventional" neutralization assay, do exhibit potent and broad neutralizing activity in "unconventional" ways. The neutralizing activity of these antibodies and IgG fractions is acquired through post-translational modifications, through opsonization of virus particles into macrophages and immature dendritic cells (iDCs), or through expression of antibodies on the surface of HIV-1-susceptible cells. This review will focus on recent findings of this area and point out their potential applications in the development of preventive strategies against HIV.