Endotoxins are common exogenous pyrogens. Excessive endotoxins in medical devices and injections can lead to serious consequences such as sepsis, septic shock, and even death. Therefore, endotoxin detection plays a crucial role in medical, pharmaceutical, and food sectors. The wide application of Limulus amebocyte lysate (LAL) has led to a sharp decline in the number of horseshoe crabs. Moreover, the LAL assay has limitations such as interbatch variations and difficulty in quantification. The recombinant factor C (rFC) assay is stable between batches, highly sensitive, and capable of quantitation, and thus it can be used as an alternative for the LAL assay. However, the high cost and complex procedures involved in producing recombinant factor C have limited the widespread application of this method. In order to simplify the preparation and reduce the production cost of recombinant factor C, this study focuses on the production of recombinant factor C based on the baculovirus expression system. Multiple measures such as a high-yield and anti-apoptotic vector qBac-IIIG, the optimal signal peptide, and the optimized codon were used to reach the goal of endotoxin detection with cell supernatant. This method simplifies the steps of protein purification. The sensitivity of the supernatant reached 0.05 EU/mL in a 1-L fermentation system, and 500 000 detecting reactions can be supported per liter of fermentation broth. This study increases the yield and activity of recombinant factor C, simplifies the procedures of protein purification, and reduces the cost, laying a foundation for the promotion and application of recombinant factor C in endotoxin detection.
Animals ; Recombinant Proteins/genetics* ; Horseshoe Crabs/chemistry* ; Baculoviridae/metabolism* ; Endotoxins/analysis* ; Protein C/biosynthesis* ; Genetic Vectors/genetics* ; Arthropod Proteins/genetics* ; Enzyme Precursors ; Serine Endopeptidases

Human keratinocyte growth factor-1 (hKGF-1), a member of the fibroblast growth factor (FGF) family, plays crucial roles in organ development, cell proliferation, wound healing, and tissue repair, representing one of the most effective and specific growth factors for skin repair. However, obtaining recombinant hKGF-1 remains challenging due to its universally low expression efficiency in vitro. This study employs the Bombyx mori baculovirus expression system to establish a technological platform that utilizes the economically important insect Bombyx mori as a bioreactor for high-efficiency and low-cost expression and production of recombinant human keratinocyte growth factor 1 (hKGF-1) protein, ultimately achieving high-level expression of hKGF-1 in Bombyx mori ovary cell line (BmN). In this study, we optimized the hKGF-1 sequence based on the codon preference of baculovirus. By fusing hKGF-1 with polyhedrin (highly expressed in this system) and adding extra promoters and enhancers, we significantly improved the expreesion level of hKGF-1 in Bombyx mori cells. The results demonstrated that the aforementioned strategies significantly enhanced the expression level of hKGF-1 in Bombyx mori cells. SDS-PAGE and Western blotting results revealed that the highest hKGF-1 expression (accounting for 8.7% of total cellular protein) was achieved when the Polh promoter was combined in tandem with the P6.9 promoter and hKGF-1 was fused with a 15-residue polyhedrin fragment for co-expression. The optimal harvest time was determined to be 120 h post transfection. This study achieved the efficient expression of hKGF-1 in Bombyx mori cells, establishing an ideal technological platform for the industrial utilization of recombinant hKGF-1. The developed methodology not only provides valuable technical references for the production of other growth factors and complex proteins, but also demonstrates significant implications for employing silkworms as bioreactors for recombinant human protein expression.
Bombyx/metabolism* ; Animals ; Baculoviridae/metabolism* ; Humans ; Fibroblast Growth Factor 7/biosynthesis* ; Recombinant Proteins/genetics* ; Cell Line ; Genetic Vectors/genetics*

Pseudorabies (PR) is an infectious disease caused by the pseudorabies virus (PRV), affecting various domesticated and wild animals. Since pigs are the only natural hosts of PRV, PR poses a serious threat to the pig farming industry. Currently, PR is primarily prevented through vaccination with inactivated vaccines or genetically modified attenuated live vaccines. Developing safe and effective genetically engineered vaccines would facilitate the eradication and control of PR. In this study, the PRV vaccine strain Bartha-K61 was used as the reference strain. The gB protein was expressed via the baculovirus-insect cell expression system. Non-denaturing gel electrophoresis confirmed that the gB protein could form a trimeric structure. The purified gB protein was used to immunize mice, and the immune effect was evaluated by a challenge test. The results showed that the gB antigen induced a strong immune response in mice, with the serum-neutralizing antibody titer above 1:70. The lymphocyte stimulation index reached more than 1.29, and the level of (interferon gamma, IFN-γ) release was higher than 100 pg/mL. After immunization, mice were challenged with the virus at a dose of 10⁴ TCID₅₀/mL, 200 μL per mouse, and the clinical protection rate was 100%. Immunohistochemistry, histopathological section, and tissue viral load results showed that the pathological damage and viral load in the gB-immunized group were significantly lower than those in the PBS group. In summary, the gB protein obtained in this study induced strong humoral and cellular immune responses in mice, laying a foundation for developing a recombinant gB protein subunit vaccine.
Animals ; Mice ; Baculoviridae/metabolism* ; Viral Envelope Proteins/biosynthesis* ; Herpesvirus 1, Suid/genetics* ; Pseudorabies/immunology* ; Swine ; Pseudorabies Vaccines/genetics* ; Antibodies, Viral/blood* ; Insecta/cytology* ; Mice, Inbred BALB C ; Female ; Viral Vaccines/immunology*

ObjectiveTo construct a GFP-fused mouse Parkin co-regulated gene (PACRG) baculovirus recombinant PACRG/GFP-pFastBac1 vector and express the fusion protein in Sf9 insect cells.

METHODSFull-length mouse PACRG cDNA was amplified by PCR and cloned in frame to the vector pFastBac1 with eGFP (rpFBac-PACRG-GFP recombinant vector). The plasmid was transformed into DH10Bac cells to obtain the recombinant bacmid plasmid, the bacmid was transfected into Sf9 insect cells, and the expressed PACRG/GFP fusion protein was analyzed by Western blot and fluorescence microscopy.

RESULTSThe construction of the PACRG/GFP-pFastBac1 baculovirus plasmid was confirmed by sequencing and restriction enzyme digestion. Western blot showed the expression of the fusion protein carrying a green fluorescence in the Sf9 insect cells.

CONCLUSIONSConclusion: A PACRG/GFP-pFastBac1 recombinant baculovirus vector was successfully constructed and the fusion protein was highly expressed in the Sf9 insect cells. Our findings have provided a basis for further studies on the structure of the PACRG protein and regulation of spermatogenesis.

Animals ; Baculoviridae ; Blotting, Western ; DNA, Complementary ; Genetic Vectors ; Green Fluorescent Proteins ; biosynthesis ; Mice ; Plasmids ; Polymerase Chain Reaction ; Proteins ; genetics ; metabolism ; Recombinant Fusion Proteins ; biosynthesis ; Sf9 Cells ; Transfection

Baculoviruses are a family of arthropod-specific viruses that produce two morphologically distinct types of virions (budded and occlusion-derived) in their lifecycle. Baculoviruses establish infection in the midgut of their host via the oral route: occlusion-derived virions have pivotal roles in these processes. This review summarizes the basic characteristics of baculoviruses, and discusses the composition and classification of baculovirus occlusion-derived virions. The latter focuses mainly on the evolution and role of multiple occlusion-derived virions in the lifecycle of baculoviruses. These achievements should aid understanding the evolution and infection mechanisms of baculoviruses.
Animals ; Baculoviridae ; genetics ; growth & development ; physiology ; Insecta ; virology ; Viral Proteins ; genetics ; metabolism ; Virion ; genetics ; growth & development ; physiology

Hemagglutinin (HA) contains a head domain with a high degree of variability and a relatively conserved stem region. HA is the major viral antigen on the surface of the influenza virus. To define the biologic activities of chimeric HA bearing different head domains and stem regions or their potential use, a HA chimeric gene containing the head domain of the H7 subtype virus and stem region of the H3 subtype virus was modified and expressed using a baculovirus expression vector. Then, the secreted protein was purified and its biologic activities characterized. Approximately 1.4 mg/mL cH7/3 HA could be obtained, and its molecular weight was ≈ 70 kD. The trimer form of cH7/3 protein had hemagglutination activity and could be recognized by specific antibodies. The method described here can be used for further studies on the screening of HA stem-reactive antibodies or the development of vaccines with conserved epitopes.
Antibodies, Viral ; immunology ; Baculoviridae ; genetics ; metabolism ; Gene Expression ; Genetic Vectors ; genetics ; metabolism ; Hemagglutination ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; immunology ; Humans ; Influenza Vaccines ; genetics ; immunology ; Influenza, Human ; prevention & control ; virology

OBJECTIVETo investigate the methods and solve the technical bottlenecks in the preparation of recombinant human protein hZP3 using the baculovirus expression system and pave the technical ground for the production and application of recombinant hZP3.

METHODSThe recombinant vector pFASTBAC HTa-hZP3 was constructed and transferred to competent E. coli cells carrying bacmid to produce recombinant bacmid by homologous recombination. Sf9 cells were transfected with the recombinant bacmid to produce recombinant baculovirus. Full-length recombinant hZP3 (amino acids 1-424) and truncated recombinant hZP3 (amino acids 23-348) were expressed in the sf9 cells by infection with the recombinant baculovirus. The expression time of hZP3 was determined by Western blot and its purification was explored.

RESULTSThe recombinant bacmid and baculovirus were successfully constructed for expressing both the full-length and truncated hZP3. The maximal expression of recombinant hZP3 in the sf9 cells was achieved at 72-96 hours after baculovirus infection. Some of the recombinant hZP3 with His-tag could bind affinity matrix and got purified but most of the solubilized hZP3 passed through and the reasons remained unknown. Purified recombinant hZP3 labeled with Dylight Dye488 was able to bind human sperm.

CONCLUSIONIt is feasible to express recombinant hZP3 in insect cells using the baculovirus system though the yield of hZP3 needs to be optimized. The methods for efficient enrichment and purification of recombinant hZP3 require further exploration.

Baculoviridae ; genetics ; metabolism ; Blotting, Western ; Egg Proteins ; genetics ; metabolism ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Humans ; Membrane Glycoproteins ; genetics ; metabolism ; Receptors, Cell Surface ; genetics ; metabolism ; Recombinant Proteins ; genetics ; metabolism ; Transfection ; methods ; Zona Pellucida Glycoproteins

OBJECTIVETo explore the combined anti-tumor effect of radiation therapy and gene-targeted suppression of tumor neovasculature in lung adenocarcinoma in vivo, and to explore the feasibility of micro-PET/CT in dynamic evaluation of treatment effectiveness.

METHODSThirty 5-6-week old male BALB/c nude mice were used in this study. The mouse models of xenotransplanted human lung adenocarcinoma were divided into 5 groups at random, six mice in each group: the control group, radiation treatment alone group and three groups of recombinant baculovirus plus radiation treatment (intratumoral injection, tail vein injection, and intramuscular injection). The tumor volume was measured every 2 days. Growth delay time (GD) and growth inhibition rate was calculated. FDG metabolism was evaluated by micro-PET-CT before and after treatment. The expressions of VEGF, CD31 and Ki-67 were detected by immunohistochemistry (IHC).

RESULTSThe tumor growth delay was >12 days, and the tumor inhibition rate was >45% in the recombinant baculovirus combined with radiotherapy groups, significantly higher than that of the radiotherapy alone group (P < 0.05). Immunohistochemical analysis showed that the expressions of VEGF, CD31 and Ki-67 were significantly lower than that in other groups (P < 0.05). The micro-PET-CT assessment showed that the FDG-metabolism in the recombinant baculovirus combined with radiotherapy groups was significantly reduced (P < 0.05), and the SUVmax (FDG metabolism) of transplanted tumors after treatment was also markedly decreased in comparison with that of the control group. The tumor volume after treatment was significantly correlated with SUVmax in the recombinant baculovirus intratumoral injection + radiotherapy group(r = 0.976), recombinant baculovirus intravenous injection + radiotherapy group (r = 0.954), recombinant baculovirus intramuscular injection + radiotherapy group (r = 0.929), and radiotherapy alone group (r = 0.871, P < 0.05).

CONCLUSIONSThe recombinant baculovirus containing Egr1 promoter and K5 gene combined with radiotherapy enhances the suppressing effect on the growth of lung adenocarcinoma in the tumor-bearing nude mice. The inducibility of Egr1 promoter by radiation allows the targeting and controllability of treatment. Micro-PET-CT results have a good correlation with the treatment effectiveness. Therefore, it can be used in real-time evaluation of tumor metabolic function in vivo.

Adenocarcinoma ; metabolism ; pathology ; radiotherapy ; Animals ; Baculoviridae ; genetics ; Cell Line, Tumor ; Combined Modality Therapy ; Early Growth Response Protein 1 ; genetics ; physiology ; Fluorodeoxyglucose F18 ; Genetic Therapy ; Genetic Vectors ; Humans ; Ki-67 Antigen ; metabolism ; Lung Neoplasms ; metabolism ; pathology ; radiotherapy ; Male ; Mice, Inbred BALB C ; Mice, Nude ; Molecular Targeted Therapy ; Neoplasm Transplantation ; Peptide Fragments ; genetics ; physiology ; Plasminogen ; genetics ; physiology ; Platelet Endothelial Cell Adhesion Molecule-1 ; metabolism ; Positron-Emission Tomography ; Promoter Regions, Genetic ; Random Allocation ; Recombinant Proteins ; genetics ; Tomography, X-Ray Computed ; Tumor Burden ; Vascular Endothelial Growth Factor A ; metabolism

A recombinant hemagglutinin-neuraminidase (rHN) protein from Newcastle disease virus (NDV) with hemagglutination (HA) activity was expressed in Spodoptera frugiperda cells using a baculovirus expression system. The rHN protein extracted from infected cells was used as an antigen in a hemagglutination inhibition (HI) test for the detection and titration of NDV-specific antibodies present in chicken sera. The rHN antigen produced high HA titers of 2(13) per 25 microL, which were similar to those of the NDV antigen produced using chicken eggs, and it remained stable without significant loss of the HA activity for at least 12 weeks at 4degrees C. The rHN-based HI assay specifically detected NDV antibodies, but not the sera of other avian pathogens, with a specificity and sensitivity of 100% and 98.0%, respectively, in known positive and negative chicken sera (n = 430). Compared with an NDV-based HI assay, the rHN-based HI assay had a relative sensitivity and specificity of 96.1% and 95.5%, respectively, when applied to field chicken sera. The HI titers of the rHN-based HI assay were highly correlated with those in an NDV-based HI assay (r = 0.927). Overall, these results indicate that rHN protein provides a useful alternative to NDV antigen in HI assays.
Animals ; Antibodies, Viral/*blood ; Antigens, Viral/*diagnostic use/genetics/metabolism ; Baculoviridae/genetics ; Chickens ; HN Protein/*diagnostic use/genetics/metabolism ; Hemagglutination Inhibition Tests/*methods/veterinary ; Newcastle Disease/*diagnosis/immunology/virology ; Newcastle disease virus/genetics/*immunology/metabolism ; Poultry Diseases/*diagnosis/immunology/virology ; Recombinant Proteins/diagnostic use/genetics/metabolism ; Sf9 Cells ; Spodoptera

Nucleoprotein (NP) of influenza virus is highly conserved and type-specific. NP can trigger strong cell-mediated immune responses in host and is involved in the protection against the challenges with different subtype influenza viruses. Here, NP of an avian H5N1 (A/Hubei/1/2010, HB) was expressed by baculovirus surface-display technology and its immunogenicity as well as protective mechanism was investigated in mice infection model. Western blot and immunolabeled electron microscopy assay showed NP was displayed on baculovirus surface. ELISA results showed NP could induce high level of anti-NP IgG in the sera from NP-Bac-inoculated mice. Two cellular immune peptides (NP57-74 IQNSITIERMVLSAFDER and NP441-458 RTEIIKMMESARPEDLSF) were identified by IFN-gamma ELISPOT assay. NP57-66 and NP441-450 and NP protein could be able to trigger the activation of CD4+ and CD8+ T cells, and the response of CD8+ T was more predominant. The challenge study of mice-adapted virus A/PR/8/34 (H1N1) showed that NP-Bac could reduce viral load and attenuate the damage to lung tissue. 50% protection ratio against the virus could be detected.
Animals ; Antibodies, Viral ; immunology ; Baculoviridae ; genetics ; metabolism ; Cross Protection ; Enzyme-Linked Immunospot Assay ; Female ; Humans ; Immunity, Cellular ; Influenza A Virus, H1N1 Subtype ; genetics ; immunology ; Influenza A Virus, H5N1 Subtype ; genetics ; immunology ; Influenza, Human ; immunology ; virology ; Mice ; Mice, Inbred BALB C ; RNA-Binding Proteins ; genetics ; immunology ; T-Lymphocytes ; immunology ; Viral Core Proteins ; genetics ; immunology