A highly potent and stable pan-coronavirus fusion inhibitor as a candidate prophylactic and therapeutic for COVID-19 and other coronavirus diseases

The development of broad-spectrum antivirals against human coronaviruses (HCoVs) is critical to combat the current coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants, as well as future outbreaks of emerging CoVs. We have previously identified a polyethylene glycol-conjugated (PEGylated) lipopeptide, EK1C4, with potent pan-CoV fusion inhibitory activity. However, PEG linkers in peptide or protein drugs may reduce stability or induce anti-PEG antibodies in vivo. Therefore, we herein report the design and synthesis of a series of dePEGylated lipopeptide-based pan-CoV fusion inhibitors featuring the replacement of the PEG linker with amino acids in the heptad repeat 2 C-terminal fragment (HR2-CF) of HCoV-OC43. Among these lipopeptides, EKL1C showed the most potent inhibitory activity against infection by SARS-CoV-2 and its spike (S) mutants, as well as other HCoVs and some bat SARS-related coronaviruses (SARSr-CoVs) tested. The dePEGylated lipopeptide EKL1C exhibited significantly stronger resistance to proteolytic enzymes, better metabolic stability in mouse serum, higher thermostability than the PEGylated lipopeptide EK1C4, suggesting that EKL1C could be further developed as a candidate prophylactic and therapeutic for COVID-19 and other coronavirus diseases.

Recent advances in developing small-molecule inhibitors against SARS-CoV-2

The COVID-19 pandemic caused by the novel SARS-CoV-2 virus has caused havoc across the entire world. Even though several COVID-19 vaccines are currently in distribution worldwide, with others in the pipeline, treatment modalities lag behind. Accordingly, researchers have been working hard to understand the nature of the virus, its mutant strains, and the pathogenesis of the disease in order to uncover possible drug targets and effective therapeutic agents. As the research continues, we now know the genome structure, epidemiological and clinical features, and pathogenic mechanism of SARS-CoV-2. Here, we summarized the potential therapeutic targets involved in the life cycle of the virus. On the basis of these targets, small-molecule prophylactic and therapeutic agents have been or are being developed for prevention and treatment of SARS-CoV-2 infection.

Homologous or Heterologous Booster of Inactivated Vaccine Reduces SARS-CoV-2 Omicron Variant Escape from Neutralizing Antibodies

The massive and rapid transmission of SARS-CoV-2 has led to the emergence of several viral variants of concern (VOCs), with the most recent one, B.1.1.529 (Omicron), which accumulated a large number of spike mutations, raising the specter that this newly identified variant may escape from the currently available vaccines and therapeutic antibodies. Using VSV-based pseudovirus, we found that Omicron variant is markedly resistant to neutralization of sera form convalescents or individuals vaccinated by two doses of inactivated whole-virion vaccines (BBIBP-CorV). However, a homologous inactivated vaccine booster or a heterologous booster with protein subunit vaccine (ZF2001) significantly increased neutralization titers to both WT and Omicron variant. Moreover, at day 14 post the third dose, neutralizing antibody titer reduction for Omicron was less than that for convalescents or individuals who had only two doses of the vaccine, indicating that a homologous or heterologous booster can reduce the Omicron escape from neutralizing. In addition, we tested a panel of 17 SARS-CoV-2 monoclonal antibodies (mAbs). Omicron resists 7 of 8 authorized/approved mAbs, as well as most of the other mAbs targeting distinct epitopes on RBD and NTD. Taken together, our results suggest the urgency to push forward the booster vaccination to combat the emerging SARS-CoV-2 variants.

Broad neutralization of SARS-CoV-2 variants by an inhalable bispecific single-domain antibody

The effectiveness of SARS-CoV-2 vaccines and therapeutic antibodies has been limited by the continuous emergence of viral variants, and by the restricted diffusion of antibodies from circulation into the sites of respiratory virus infection. Here, we report the identification of two highly conserved regions on Omicron variant RBD recognized by broadly neutralizing antibodies. Based on this finding, we generated a bispecific single-domain antibody that was able to simultaneously and synergistically bind these two regions on a single Omicron variant RBD as revealed by Cryo-EM structures. This inhalable antibody exhibited exquisite neutralization breadth and therapeutic efficacy in mouse models of SARS-CoV-2 infections. The structures also deciphered an uncommon cryptic epitope within the spike trimeric interface that may have implications for the design of broadly protective SARS-CoV-2 vaccines and therapeutics.

Antibody-dependent enhancement (ADE) of SARS-CoV-2 infection in recovered COVID-19 patients: studies based on cellular and structural biology analysis

Antibody-dependent enhancement (ADE) has been reported in several virus infections including dengue fever virus, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronavirus infection. To study whether ADE is involved in COVID-19 infections, in vitro pseudotyped SARS-CoV-2 entry into Raji cells, K562 cells, and primary B cells mediated by plasma from recovered COVID-19 patients were employed as models. The enhancement of SARS-CoV-2 entry into cells was more commonly detected in plasma from severely-affected elderly patients with high titers of SARS-CoV-2 spike protein-specific antibodies. Cellular entry was mediated via the engagement of Fc{gamma}RII receptor through virus-cell membrane fusion, but not by endocytosis. Peptide array scanning analyses showed that antibodies which promote SARS-CoV-2 infection targeted the variable regions of the RBD domain. To further characterize the association between the spike-specific antibody and ADE, an RBD-specific monoclonal antibody (7F3) was isolated from a recovered patient, which potently inhibited SARS-Cov-2 infection of ACE-2 expressing cells and also mediated ADE in Raji cells. Site-directed mutagenesis the spike RBD domain reduced the neutralization activity of 7F3, but did not abolish its binding to the RBD domain. Structural analysis using cryo-electron microscopy (Cryo-EM) revealed that 7F3 binds to spike proteins at a shift-angled pattern with one "up" and two "down" RBDs, resulting in partial overlapping with the receptor binding motif (RBM), while a neutralizing monoclonal antibody that lacked ADE activity binds to spike proteins with three "up" RBDs, resulting in complete overlapping with RBM. Our results revealed that ADE mediated by SARS-CoV-2 spike-specific antibodies could result from binding to the receptor in slightly different pattern from antibodies mediating neutralizations. Studies on ADE using antibodies from recovered patients via cell biology and structural biology technology could be of use for developing novel therapeutic and preventive measures for control of COVID-19 infection.

Distinct mechanisms for TMPRSS2 expression explain organ-specific inhibition of SARS-CoV-2 infection by enzalutamide

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly become a global public health threat due to the lack of effective drugs or vaccines against SARS-CoV-2. The efficacy of several repurposed drugs has been evaluated in clinical trials. Among these drugs, a relatively new antiandrogen agent, enzalutamide, was proposed because it reduces the expression of transmembrane serine protease 2 (TMPRSS2), a key component mediating SARS-CoV-2-driven entry into host cells, in prostate cancer cells. However, definitive evidence for the therapeutic efficacy of enzalutamide in COVID-19 is lacking. Here, we evaluated the antiviral efficacy of enzalutamide in prostate cancer cells, lung cancer cells, human lung organoids and SARS-CoV-2-infected Ad-ACE2-transduced Tmprss2 knockout (Tmprss2-KO) and wild-type (WT) mice. TMPRSS2 knockout significantly inhibited SARS-CoV-2 infection in vivo. Enzalutamide effectively inhibited SARS-CoV-2 infection in human prostate cancer cells (LNCaP) but not in human lung cancer cells or patient-derived lung organoids. Although Tmprss2 knockout effectively blocked SARS-CoV-2 infection in ACE2-transduced mice, enzalutamide showed no antiviral activity due to the AR independence of TMPRSS2 expression in mouse and human lung epithelial cells. Moreover, we observed distinct AR binding patterns between prostate cells and lung cells and a lack of direct binding of AR to TMPRSS2 in human lung cells. Thus, our findings do not support the postulated protective role of enzalutamide in treating COVID-19.

Long-term survival of salmon-attached SARS-CoV-2 at 4 degree as a potential source of transmission in seafood markets

Several outbreaks of COVID-19 were associated with seafood markets, raising concerns that fish-attached SARS-CoV-2 may exhibit prolonged survival in low-temperature environments. Here we showed that salmon-attached SARS-CoV-2 at 4{degrees}C could remain infectious for more than one week, suggesting that fish-attached SARS-CoV-2 may be a source of transmission.

Engineered Trimeric ACE2 Binds and Locks "Three-up" Spike Protein to Potently Inhibit SARS-CoVs and Mutants

SARS-CoV-2 enters cells via ACE-2, which binds the spike protein with moderate affinity. Despite a constant background mutational rate, the virus must retain binding with ACE2 for infectivity, providing a conserved constraint for SARS-CoV-2 inhibitors. To prevent mutational escape of SARS-CoV-2 and to prepare for future related coronavirus outbreaks, we engineered a de novo trimeric ACE2 (T-ACE2) protein scaffold that binds the trimeric spike protein with extremely high affinity (KD < 1 pM), while retaining ACE2 native sequence. T-ACE2 potently inhibits all tested pseudotyped viruses including SARS-CoV-2, SARS-CoV, eight naturally occurring SARS-CoV-2 mutants, two SARSr-CoVs as well as authentic SARS-CoV-2. The cryo-EM structure reveals that T-ACE2 can induce the transit of spike protein to "three-up" RBD conformation upon binding. T-ACE2 thus represents a promising class of broadly neutralizing proteins against SARS-CoVs and mutants.

Yeast-Expressed SARS-CoV Recombinant Receptor-Binding Domain (RBD219-N1) Formulated with Alum Induces Protective Immunity and Reduces Immune Enhancement

We developed a severe acute respiratory syndrome (SARS) subunit recombinant protein vaccine candidate based on a high-yielding, yeast-engineered, receptor-binding domain (RBD219-N1) of the SARS beta-coronavirus (SARS-CoV) spike (S) protein. When formulated with Alhydrogel®, RBD219-N1 induced high-level neutralizing antibodies against both pseudotyped virus and a clinical (mouse-adapted) isolate of SARS-CoV. Here, we report that mice immunized with RBD219-N1/Alhydrogel® were fully protected from lethal SARS-CoV challenge (0% mortality), compared to ∼ 30% mortality in mice when immunized with the SARS S protein formulated with Alhydrogel®, and 100% mortality in negative controls. An RBD219-N1 formulation Alhydrogel® was also superior to the S protein, unadjuvanted RBD, and AddaVax (MF59-like adjuvant)-formulated RBD in inducing specific antibodies and preventing cellular infiltrates in the lungs upon SARS-CoV challenge. Specifically, a formulation with a 1:25 ratio of RBD219-N1 to Alhydrogel® provided high neutralizing antibody titers, 100% protection with non-detectable viral loads with minimal or no eosinophilic pulmonary infiltrates. As a result, this vaccine formulation is under consideration for further development against SARS-CoV and potentially other emerging and re-emerging beta-CoVs such as SARS-CoV-2.Competing Interest StatementThe authors have declared no competing interest.View Full Text

Neutralizing antibody responses to SARS-CoV-2 in a COVID-19 recovered patient cohort and their implications

BackgroundThe COVID-19 pandemic caused by SARS-CoV-2 coronavirus threatens global public health. Currently, neutralizing antibodies (NAbs) versus this virus are expected to correlate with recovery and protection of this disease. However, the characteristics of these antibodies have not been well studied in association with the clinical manifestations in patients. MethodsPlasma collected from 175 COVID-19 recovered patients with mild symptoms were screened using a safe and sensitive pseudotyped-lentiviral-vector-based neutralization assay. Spike-binding antibody in plasma were determined by ELISA using RBD, S1, and S2 proteins of SARS-CoV-2. The levels and the time course of SARS-CoV-2-specific NAbs and the spike-binding antibodies were monitored at the same time. FindingsSARS-CoV-2 NAbs were unable to cross-reactive with SARS-CoV virus. SARS-CoV-2-specific NAbs were detected in patients from day 10-15 after the onset of the disease and remained thereafter. The titers of NAb among these patients correlated with the spike-binding antibodies targeting S1, RBD, and S2 regions. The titers of NAbs were variable in different patients. Elderly and middle-age patients had significantly higher plasma NAb titers (P<0.0001) and spike-binding antibodies (P=0.0003) than young patients. Notably, among these patients, there were ten patients whose NAb titers were under the detectable level of our assay (ID50: < 40); while in contrast, two patients, showed very high titers of NAb, with ID50 :15989 and 21567 respectively. The NAb titers were positive correlated with plasma CRP levels but negative correlated with the lymphocyte counts of patients at the time of admission, indicating an association between humoral response and cellular immune response. InterpretationThe variations of SARS-CoV-2 specific NAbs in recovered COVID-19 patients may raise the concern about the role of NAbs on disease progression. The correlation of NAb titers with age, lymphocyte counts, and blood CRP levels suggested that the interplay between virus and host immune response in coronavirus infections should be further explored for the development of effective vaccine against SARS-CoV-2 virus. Furthermore, titration of NAb is helpful prior to the use of convalescent plasma for prevention or treatment. FundingMinistry of Science and Technology of China, National Natural Science Foundation of China, Shanghai Municipal Health Commission, and Chinese Academy of Medical Sciences

Fully human single-domain antibodies against SARS-CoV-2

The COVID-19 pandemic is spreading rapidly, highlighting the urgent need for an efficient approach to rapidly develop therapeutics and prophylactics against SARS-CoV-2. We describe here the development of a phage-displayed single-domain antibody library by grafting naive CDRs into framework regions of an identified human germline IGHV allele. This enabled the isolation of high-affinity single-domain antibodies of fully human origin. The panning using SARS-CoV-2 RBD and S1 as antigens resulted in the identification of antibodies targeting five types of neutralizing or non-neutralizing epitopes on SARS-CoV-2 RBD. These fully human single-domain antibodies bound specifically to SARS-CoV-2 RBD with subnanomolar to low nanomolar affinities. Some of them were found to potently neutralize pseudotyped and live virus, and therefore may represent promising candidates for prophylaxis and therapy of COVID-19. This study also reports unique immunogenic profile of SARS-CoV-2 RBD compared to that of SARS-CoV and MERS-CoV, which may have important implications for the development of effective vaccines against SARS-CoV-2.

Inhibition of SARS-CoV-2 infection (previously 2019-nCoV) by a highly potent pan-coronavirus fusion inhibitor targeting its spike protein that harbors a high capacity to mediate membrane fusion

The recent outbreak of coronavirus disease (COVID-19) caused by SARS-CoV-2 infection in Wuhan, China has posed a serious threat to global public health. To develop specific anti-coronavirus therapeutics and prophylactics, the molecular mechanism that underlies viral infection must first be confirmed. Therefore, we herein used a SARS-CoV-2 spike (S) protein-mediated cell-cell fusion assay and found that SARS-CoV-2 showed plasma membrane fusion capacity superior to that of SARS-CoV. We solved the X-ray crystal structure of six-helical bundle (6-HB) core of the HR1 and HR2 domains in SARS-CoV-2 S protein S2 subunit, revealing that several mutated amino acid residues in the HR1 domain may be associated with enhanced interactions with HR2 domain. We previously developed a pan-coronavirus fusion inhibitor, EK1, which targeted HR1 domain and could inhibit infection by divergent human coronaviruses tested, including SARS-CoV and MERS-CoV. We then generated a series of lipopeptides and found that the EK1C4 was the most potent fusion inhibitor against SARS-CoV-2 S protein-mediated membrane fusion and pseudovirus infection with IC50s of 1.3 and 15.8 nM, about 241- and 149-fold more potent than that of EK1 peptide, respectively. EK1C4 was also highly effective against membrane fusion and infection of other human coronavirus pseudoviruses tested, including SARS-CoV and MERS-CoV, as well as SARSr-CoVs, potently inhibiting replication of 4 live human coronaviruses, including SARS-CoV-2. Intranasal application of EK1C4 before or after challenge with HCoV-OC43 protected mice from infection, suggesting that EK1C4 could be used for prevention and treatment of infection by currently circulating SARS-CoV-2 and emerging SARSr-CoVs.

Potent binding of 2019 novel coronavirus spike protein by a SARS coronavirus-specific human monoclonal antibody

The newly identified 2019 novel coronavirus (2019-nCoV) has caused more than 800 laboratory-confirmed human infections, including 25 deaths, posing a serious threat to human health. Currently, however, there is no specific antiviral treatment or vaccine. Considering the relatively high identity of receptor binding domain (RBD) in 2019-nCoV and SARS-CoV, it is urgent to assess the cross-reactivity of anti-SARS-CoV antibodies with 2019-nCoV spike protein, which could have important implications for rapid development of vaccines and therapeutic antibodies against 2019-nCoV. Here, we report for the first time that a SARS-CoV-specific human monoclonal antibody, CR3022, could bind potently with 2019-nCoV RBD (KD of 6.3 nM). The epitope of CR3022 does not overlap with the ACE2 binding site within 2019-nCoV RBD. Therefore, CR3022 has the potential to be developed as candidate therapeutics, alone or in combination with other neutralizing antibodies, for the prevention and treatment of 2019-nCoV infections. Interestingly, some of the most potent SARS-CoV-specific neutralizing antibodies (e.g., m396, CR3014) that target the ACE2 binding site of SARS-CoV failed to bind 2019-nCoV spike protein, indicating that the difference in the RBD of SARS-CoV and 2019-nCoV has a critical impact for the cross-reactivity of neutralizing antibodies, and that it is still necessary to develop novel monoclonal antibodies that could bind specifically to 2019-nCoV RBD.

The development of HIV vaccines targeting gp41 membrane-proximal external region (MPER): challenges and prospects

A human immunodeficiency virus type-1 (HIV-1) vaccine which is able to effectively prevent infection would be the most powerful method of extinguishing pandemic of the acquired immunodeficiency syndrome (AIDS). Yet, achieving such vaccine remains great challenges. The membrane-proximal external region (MPER) is a highly conserved region of the envelope glycoprotein (Env) gp41 subunit near the viral envelope surface, and it plays a key role in membrane fusion. It is also the target of some reported broadly neutralizing antibodies (bNAbs). Thus, MPER is deemed to be one of the most attractive vaccine targets. However, no one can induce these bNAbs by immunization with immunogens containing the MPER sequence(s). The few attempts at developing a vaccine have only resulted in the induction of neutralizing antibodies with quite low potency and limited breadth. Thus far, vaccine failure can be attributed to various characteristics of MPER, such as those involving structure and immunology; therefore, we will focus on these and review the recent progress in the field from the following perspectives: (1) MPER structure and its role in membrane fusion, (2) the epitopes and neutralization mechanisms of MPER-specific bNAbs, as well as the limitations in eliciting neutralizing antibodies, and (3) different strategies for MPER vaccine design and current harvests.

Small molecular agents against MERS-CoV infection / 药学学报

Middle East respiratory syndrome coronavirus (MERS-CoV) has caused outbreaks of SARS-like disease with 35% case-fatality rate, mainly in the Middle East. A more severe outbreak of MERS occurred recently in the Republic of Korea, where 186 people contracted the infections, causing great concern worldwide. So far, there has been no clinically available drug for the treatment of MERS-CoV infection. The potential drugs against MERS-CoV mainly consist of monoclonal antibodies, peptides and small molecular agents. Small molecular agents have an advantage of easier synthesis, lower cost in production and relatively higher stability. There is better chance for those candidates to gain a quick development. This article reviews the progress of developing small molecular MERS-CoV agents.

Development of peptidic MERS-CoV entry inhibitors / 药学学报

In 2012, a new SARS-like coronavirus emerged in the Middle East, namely the Middle East respiratory syndrome coronavirus (MERS-CoV). It has caused outbreaks with high mortality. During infection of target cell, MERS-CoV S protein S1 subunit binds to the cellular receptor (DPP4), and its S2 subunit HR1 and HR2 regions intact with each other to form a stable six-helix bundle to mediate the fusion between virus and target cell membranes. Hence, blocking the process of six-helix bundle formation can effectively inhibit MERS-CoV entry into the target cells. This review focuses on the recent advance in the development of peptidic entry inhibitors targeting the MERS-CoV S2 subunit.

Peptidic HIV-1 fusion inhibitor VIR576 as a potential dual- functional microbicide inhibits antigen-specific CD4(+) T-cell activation / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe if VIR576, an 20-mer peptide derived from the C-proximal subfragment of a1-antitrypsin (a1-AT) which inhibits human immunodeficiency virus type 1 (HIV-1) entry into the target cells by interacting with fusion peptide (FP), can also directly inhibit CD4(+) T cell activation in vitro.</p><p><b>METHODS</b>Splenocytes isolated from DO11.10 OVA Tg mice were stimulated with ovalbumin or concanavalin A to test the effects of VIR576 on antigen-specific or non-antigen-specific T cell activation. Both primary CD4(+)CD25(-) T cells from DO11.10 mice and CD4(+) T cell line A2b were activated with specific antigens to evaluate the effects of VIR576.</p><p><b>RESULTS</b>VIR576 inhibited antigen-specific splenocyte activation but had no significant effect on non-antigen-specific T-cell activation, which bypassed the crosstalk between the CD3-signaling complex and TCR. We furthermore observed that VIR576 could also down-regulate antigen-specific CD4(+) T-cell activation.</p><p><b>CONCLUSIONS</b>Given the high susceptibility of activated CD4(+) T cells in the mucosa to HIV-1 infection, the inhibitory effects of VIR576 on both HIV entry into the target cells and CD4(+) T-cell activation suggest the potential of VIR576 as a microbicide for prevention of sexual transmission of HIV.</p>

Design,synthesis and activity evaluation of new anti-HIV-1 CXCR4 inhibitors / 军事医学

Objective To design and synthesize a series of new type four hydrogen quinoline-benzyl/benzimidazole amine derivatives as a potential new inhibitor targeting auxiliary receptor CXCR 4, and determine their inhibitory activities to HIV-1.Methods Based on HIV-1 receptor CXCR4 inhibitors containing three nitrogen structure-activity motif and CCR5 partial hydrophobic pharmacophore , a series of new compounds were designed , synthesized and characterized by 1 HNMR and MS.The inhibitory activities of these compounds were determined using HIV-1 IIIB virus.Results and Conclusion Ten target compounds are synthesized .Four hydrogen quinoline-benzimidazole amine derivatives exhibit good anti-HIV activity(IC50 8 μmol/L).

Virtual screening of small molecular HIV-1 entry inhibitor NC-2 targeting gp120 and its action mechanism / 南方医科大学学报

<p><b>OBJECTIVE</b>To screen the HIV-1 entry inhibitors targeting HIV-1 gp120 from the IBS natural product database by virtual screening based on the binding mode of the neutralizing antibody VRC01 with HIV-1 gp120 and investigate the anti-viral activities of the inhibitors and their action mechanisms.</p><p><b>METHODS</b>The binding interaction of the candidate molecules binding gp120 and changes of the binding free energy were analyzed by MM-PBSA calculation. The anti-HIV-1 activities of the tested compounds were detected by HIV-1 pseudotyped virus, laboratory-adapted HIV-1 and a cell-cell fusion assay. The cytotoxicity of the studied molecules was examined by XTT colorimetric assay. The mechanisms of the anti-viral activities of the candidate molecules were analyzed using enzyme-linked immunosorbent assay.</p><p><b>RESULTS</b>A total of 19 molecules with distinct reduction of the binding free energy after binding with gp120 were screened from 40000 molecules. Among them, NC-2 showed anti-HIV-1 activities against HIV-1 pseudotyped virus and laboratory-adapted HIV-1, and was capable of blocking HIV-1 envelope-mediated cell-cell fusion. The IC50 of NC-2 for inhibiting HIV-1IIIB and pseudotyped HIV-1JRFL infection were 1.95∓0.44 µmol/L and 10.58∓0.13 µmol/L, respectively. The results of ELISA suggested that NC-2 could inhibit the binding of HIV-1 gp120 to CD4 without blocking the formation of gp41 six-helix bundle in vitro.</p><p><b>CONCLUSION</b>This computer-based virtual screening method can be used to screen HIV-1 entry inhibitors targeting gp120. Using this virtual screening approach combined with anti-viral activity screening, we obtained a potent HIV-1 entry inhibitor NC-2 with novel structure.</p>

Construction of personalized full-length fully human mammalian display antibody library for children with systemic lupus erythematosus / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a personalized full-length fully human antibody mammalian display library for children with systemic lupus erythematosus (SLE).</p><p><b>METHODS</b>The total RNA was isolated from the PBMCs of SLE children. The heavy chain variable region and kappa light chain (VH and LCκ) of the antibody genes were amplified by RT-PCR and inserted into the pDGB-HC-TM vector separately to construct the heavy chain and light chain libraries. The library DNAs were transfected into 293T cells and the expression of full-length fully human antibody on the surface of 293T cells was analyzed by flow cytometry.</p><p><b>RESULTS</b>Using 0.8 µg total RNA as the template, the VH and LCκ were amplified and the full-length fully human antibody mammalian display library was constructed. The VH and LCκ gene libraries had a size of 9.4×10(4) and 8.4×10(4), respectively. Sequence analysis of 10 clones randomly selected from the VH and LCκ gene libraries each showed that 8 heavy chain clones and 7 light chain clones contained correct open reading frames, and flow cytometry demonstrated that all the 15 clones express full-length antibodies on 293T cell surfaces. 293T cells co-transfected with the VH and LCκ gene libraries expressed the full-length antibodies on the cell surface.</p><p><b>CONCLUSION</b>The personalized full-length fully human antibody library for SLE children constructed allows display of the full-length antibodies on mammalian cell surfaces, thus providing a valuable platform for analyzing the autoantibodies, their etiological role, and their clinical implications in SLE.</p>