Production of highly and broad-range specific monoclonal antibodies against hemagglutinin of H5-subtype avian influenza viruses and their differentiation by mass spectrometry

Salmonella delivers H9N2 influenza virus antigens via a prokaryotic and eukaryotic dual-expression vector and elicits bivalent protection against avian influenza and fowl typhoid

The H9N2 avian influenza virus significantly affects the health of poultry and humans. We identified a prokaryotic and eukaryotic dual-expression vector system, pJHL270, that can provide simultaneous MHC class I and II stimulation of the host immune system, and we designed vaccine antigens by selecting the consensus HA1 sequence and M2e antigens from H9N2 virus circulating in South Korea from 2000 to 2021. The genes were cloned into the pJHL270 vector, and the cloned plasmid was delivered by a live-attenuated Salmonella Gallinarum (SG) strain. The immunity and protective efficacy of the SG-based H9N2 vaccine construct, JOL2922, against avian influenza and fowl typhoid (FT) were evaluated. The Ptrc and CMV promoters conferred antigen expression in prokaryotic and eukaryotic cells to induce balanced Th-1/Th-2 immunity. Chickens immunized with JOL2922 yielded high antigen-specific humoral and mucosal immune responses. qRT-PCR revealed that the strain generated polyfunctional IFN-γ and IL-4 secretion in immunized chickens. Furthermore, a FACS analysis showed increased CD3CD4+ and CD3CD8+ T-cell subpopulations following immunization. Peripheral Blood Mononuclear Cells (PBMCs) harvested from the immunized chickens significantly increased MHC class I and II expression, 3.5-fold and 2.5-fold increases, respectively. Serum collected from the immunized groups had an evident hemagglutinin inhibition titer of ≥6 log2. Immunization reduced the lung viral titer by 3.8-fold within 5 days post-infection. The strain also generated SG-specific humoral and cellular immune responses. The immunized birds all survived a virulent SG wild-type challenge. In addition, the bacterial burden was reduced by 2.7-fold and 2.1-fold in spleen and liver tissue, respectively, collected from immunized chickens. Our data indicate that an attenuated SG strain successfully delivered the dual-expression vector system and co-stimulated MHC class I and II antigen presentation pathways via exogenous and endogenous antigen presentation, thereby triggering a balanced Th-1/Th-2-based immune response and conferring effective protection against avian influenza and FT.

Expression of the gene encoding blood coagulation factor VIII without domain B in E. coli bacterial expression system

In this article, we have demonstrated the feasibility of generating an active form of recombinant blood coagulation factor VIII using an E. coli bacterial expression system as a potential treatment for hemophilia type A. Factor VIII (FVIII), an essential blood coagulation protein, is a key component of the fluid phase blood coagulation system. So far, all available recombinant FVIII formulations have been produced using eukaryotic expression systems. Mammalian cells can produce catalytically active proteins with all the necessary posttranslational modifications. However, cultivating such cells is time-consuming and highly expensive, and the amount of the obtained product is usually low. In contrast to eukaryotic cells, bacterial culture is inexpensive and allows the acquisition of large quantities of recombinant proteins in a short time. With this study, we aimed to obtain recombinant blood coagulation factor VIII using the E. coli bacterial expression system, a method not previously explored for this purpose. Our research encompasses the synthesis of blood coagulation factor VIII and its expression in a prokaryotic system. To achieve this, we constructed a prokaryotic expression vector containing a synthetic factor VIII gene, which was then used for the transformation of an E. coli bacterial strain. The protein expression was confirmed by mass spectrometry, and we assessed the stability of the gene construct while determining the optimal growth conditions. The production of blood coagulation factor VIII by the E. coli bacterial strain was carried out on a quarter-technical scale. We established the conditions for isolation, denaturation, and renaturation of the protein, and subsequently confirmed the activity of FVIII.

Magnetic graphene oxide, a suitable support in ficin immobilization

In the present study, we aimed to develop a fast, non-toxic ultrasonic-assisted technique for the preparation of graphene oxide (GO) and GO that were accessorized with Fe₃O₄ (GO-Fe₃O₄) for enzyme immobilization. The structural properties of nanosheets were determined by FTIR, XRD, and SEM. Immobilized enzymes on the GO-Fe₃O₄ and GO were counted. Enzyme activity, reusability, and improvements in enzyme stability were studied. According to the results, the immobilization efficiency was 256.86 mg ficin/GO (g), and 253.63 mg ficin/GO-Fe₃O₄ (g). Furthermore, immobilized ficin was affected in terms of stability by variations in pH and temperature. The immobilized ficin on the GO-Fe₃O₄ could be easily recycled from the reaction medium by applying external magnetic separation, involving 10 cycles for 120 days. Over this period and with this number of cycles, the immobilized enzyme on the GO-Fe₃O₄ retained 74% of its original activity, whereas the immobilized enzyme on the GO was recycled from the reaction medium after centrifuging, thereby retaining 70% of its original activity. Thus, GO and GO-Fe₃O₄ nanosheets were obtained efficiently from the ultrasonic-assisted technique and can be regarded as excellent nanocarriers for enzyme immobilization.

Development of a Rapid Fluorescent Diagnostic System for Early Detection of the Highly Pathogenic Avian Influenza H5 Clade 2.3.4.4 Viruses in Chicken Stool

Rapid diagnosis is essential for the control and prevention of H5 highly pathogenic avian influenza viruses (HPAIVs). However, highly sensitive and rapid diagnostic systems have shown limited performance due to specific antibody scarcity. In this study, two novel specific monoclonal antibodies (mAbs) for clade 2.3.4.4 H5Nx viruses were developed by using an immunogen from a reversed genetic influenza virus (RGV). These mAbs were combined with fluorescence europium nanoparticles and an optimized lysis buffer, which were further used for developing a fluorescent immunochromatographic rapid strip test (FICT) for early detection of H5Nx influenza viruses on chicken stool samples. The result indicates that the limit of detection (LoD) of the developed FICT was 40 HAU/mL for detection of HPAIV H5 clade 2.3.4.4b in spiked chicken stool samples, which corresponded to 4.78 × 10⁴ RNA copies as obtained from real-time polymerase chain reaction (RT-PCR). An experimental challenge of chicken with H5N6 HPAIV is lethal for chicken three days post-infection (DPI). Interestingly, our FICT could detect H5N6 in stool samples at 2 DPI earlier, with 100% relative sensitivity in comparison with RT-PCR, and it showed 50% higher sensitivity than the traditional colloidal gold-based rapid diagnostic test using the same mAbs pair. In conclusion, our rapid diagnostic method can be utilized for the early detection of H5Nx 2.3.4.4 HPAIVs in avian fecal samples from poultry farms or for influenza surveillance in wild migratory birds.

A novel epitope-blocking ELISA for specific and sensitive detection of antibodies against H5-subtype influenza virus hemagglutinin

Background

H5-subtype highly pathogenic (HP) avian influenza viruses (AIVs) cause high mortality in domestic birds and sporadic infections in humans with a frequently fatal outcome, while H5N1 viruses have pandemic potential. Due to veterinary and public health significance, these HPAIVs, as well as low pathogenicity (LP) H5-subtype AIVs having a propensity to mutate into HP viruses, are under epidemiologic surveillance and must be reported to the World Organization for Animal Health (OIE). Our previous work provided a unique panel of 6 different monoclonal antibodies (mAbs) against H5 hemagglutinin (HA), which meets the demand for high-specificity tools for monitoring AIV infection and vaccination in poultry. In this study, we selected one of these mAbs to develop an epitope-blocking (EB) ELISA for detecting H5 subtype-specific antibodies in chicken sera (H5 EB-ELISA).

Methods

In the H5 EB-ELISA, H5 HA protein produced in a baculovirus-expression vector system was employed as a coating antigen, and the G-7-27-18 mAb was employed as a blocking antibody. The performance characteristics of the assay were evaluated by testing 358 sera from nonimmunized chickens and chickens immunized with AIVs of the H1–H16 subtypes or recombinant H5 HA antigen to obtain the reference and experimental antisera, respectively. The samples were classified as anti-H5 HA positive or negative based on the results of the hemagglutination inhibition (HI) assay, the gold standard in subtype-specific serodiagnosis.

Results

The H5 EB-ELISA correctly discriminated between the anti-H5 HA negative sera, including those against the non-H5 subtype AIVs, and sera positive for antibodies against the various-origin H5 HAs. Preliminary validation showed 100% analytical and 97.6% diagnostic specificities of the assay and 98.0% and 99.1% diagnostic sensitivities when applied to detect the anti-H5 HA antibodies in the reference and experimental antisera, respectively.

Conclusions

The H5 EB-ELISA performed well in terms of diagnostic estimates. Thus, further optimization and validation work using a larger set of chicken sera and receiver operating characteristic (ROC) analysis are warranted. Moreover, the present assay provides a valuable basis for developing multispecies screening tests for birds or diagnostic tests for humans.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01564-6.

Bacterial expression and characterization of an anti-CD22 single-chain antibody fragment

Single-chain variable fragment (scFv) antibodies are fusion proteins of the variable regions of the heavy and light chains of immunoglobulins connected with a short linker peptide. They possess unique and superior features compared to whole antibodies for immunotherapy of various carcinomas, including hematologic B-cell malignancies. In the presented study we obtained efficient production of the recombinant anti-CD22 scFv in Escherichia coli expression system. The active recombinant protein was successfully recovered from inclusion bodies. Assays were performed to assess the in vitro targeting properties and specificity of the obtained anti-CD22 scFv antibody in the CD22 positive and negative lymphoma cell lines.

Prime-Boost Vaccination With a Novel Hemagglutinin Protein Produced in Bacteria Induces Neutralizing Antibody Responses Against H5-Subtype Influenza Viruses in Commercial Chickens

The highly pathogenic (HP) avian influenza virus (AIV), H5N1 and reassortant H5-subtype HPAIVs, H5N2, H5N6, and H5N8, cause high mortality in domestic birds, resulting in economic losses in the poultry industry. H5N1 and H5N6 also pose significant public health risks and H5N1 viruses are a permanent pandemic threat. To control HPAIVs, eukaryotic expression systems have traditionally been exploited to produce vaccines based on hemagglutinin (HA), a protective viral antigen. In contrast, we used a bacterial expression system to produce vaccine targeting the HA protein. A fragment of the HA ectodomain from H5N1, with a multibasic cleavage site deletion, was expressed in Escherichia coli, refolded, and chromatographically purified from inclusion bodies. The resulting antigen, rH5-E. coli, was validated in terms of conformational integrity and oligomerization status. Previously, the protective efficacy of rH5-E. coli adjuvanted with aluminum hydroxide, has been positively verified by challenging the specific pathogen-free layer chickens with homologous and heterologous H5N1 HPAIVs. Protection was provided primarily by the H5 subtype-specific antibodies, as detected in the FluAC H5 test. The present studies were conducted to assess the performance of alum-adjuvanted rH5-E. coli in commercial birds. Broiler chickens were vaccinated twice with 25 μg of rH5-E. coli at 2- and 4-week intervals, while the layer chickens were vaccinated with 5- to 25-μg antigen doses at 4- and 6-week intervals. Post-vaccination sera were analyzed for anti-H5 HA antibodies, using homologous ELISA and heterologous FluAC H5 and hemagglutination inhibition (HI) tests. Prime-boost immunizations with rH5-E. coli elicited H5 HA-specific antibodies in all the chickens tested. Two antigen doses administered at 4- or 6-week intervals were sufficient to induce neutralizing antibodies against H5-subtype HAs; however, they were ineffective when applied with a 2-week delay. In the layers, 80% to 100% of individuals developed antibodies that were active in the FluAC H5 and/or HI tests. A dose-sparing effect was seen when using the longer prime-boost interval. In the broiler chickens, 62.5% positivity was achieved in the FluAC H5 and/or HI tests. The trials confirmed the vaccine potential of rH5-E. coli and provided indications for anti-influenza vaccination with respect to the chicken type and immunization scheme.