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Human growth hormone (hGH) is a peptide hormone secreted by eosinophils of the human anterior pituitary, and a regulatory factor for a variety of metabolic pathways. A 30-kD protein from the pupa stage of silkworm was detected by Western blotting and confirmed by immunoprecipitation based on its ability to bind to anti-hGH antibody. This protein, named BmhGH-like protein, was purified from fresh silkworm pupas through low-temperature homogenization, filtration, and centrifugation to remove large impurity particles. The supernatants were precipitated, resuspended, and passed through a molecular sieve. Further purification by affinity chromatography and two-dimensional electrophoresis resulted in pure protein for analysis by MS MALDI-TOF-MS analysis. An alignment with predicted proteins indicated that BmhGH-like protein consisted of two lipoproteins, which we named hGH-L1 and hGH-L2. These proteins belong to the β-trefoil superfamily, with β domains similar to the spatial structure of hGH. Assays with K562 cells demonstrated that these proteins could promote cell division in vitro. To further validate the growth-promoting effects, hGH-L2 was cloned from pupa cDNA to create recombinant silkworm baculovirus vBmNPV-hGH-L2, which was used to infect silkworm BmN cells at low titer. Flow cytometric analysis demonstrated that the protein shortened the G0/G1 phase of the cells, and enabled the cells to rapidly traverse the G1/S phase transition point to enter S phase and promote cell division. Discovery of hGH-like protein in silkworm will once again arouse people’s interest in the potential medicinal value of silkworm and establish the basis for the development of new hormone drugs. [ABSTRACT FROM AUTHOR]

A key molecule in the pathogenesis of Alzheimer's disease (AD) is a 42-amino acid isoform of the amyloid-β peptide (Aβ42), which is the most toxic element of senile plaques. In this study, to develop an edible, safe, low-cost vaccine for AD, a cholera toxin B subunit (CTB)-Aβ42 fusion protein was successfully expressed in silkworm pupae. We tested the silkworm pupae-derived oral vaccination containing CTB-Aβ42 in a transgenic mouse model of AD. Anti-Aβ42 antibodies were induced in these mice, leading to a decreased Aβ deposition in the brain. We also found that the oral administration of the silk worm pupae vaccine improved the memory and cognition of mice, as assessed using a water maze test. These results suggest that the new edible CTB-Aβ42 silkworm pupae-derived vaccine has potential clinical application in the prevention of AD. [ABSTRACT FROM AUTHOR]

We identified a novel gene encoding a Bombyx mori thymosin (BmTHY) protein from a cDNA library of silkworm pupae, which has an open reading frame (ORF) of 399 bp encoding 132 amino acids. It was found by bioinformatics that BmTHY gene consisted of three exons and two introns and BmTHY was highly homologous to thymosin betas (Tβ). BmTHY has a conserved motif LKHTET with only one amino acid difference from LKKTET, which is involved in Tβ binding to actin. A His-tagged BmTHY fusion protein (rBmTHY) with a molecular weight of approximately 18.4 kDa was expressed and purified to homogeneity. The purified fusion protein was used to produce anti-rBmTHY polyclonal antibodies in a New Zealand rabbit. Subcellular localization revealed that BmTHY can be found in both Bm5 cell (a silkworm ovary cell line) nucleus and cytoplasm but is primarily located in the nucleus. Western blotting and real-time RT-PCR showed that during silkworm developmental stages, BmTHY expression levels are highest in moth, followed by instar larvae, and are lowest in pupa and egg. BmTHY mRNA was universally distributed in most of fifth-instar larvae tissues (except testis). However, BmTHY was expressed in the head, ovary and epidermis during the larvae stage. BmTHY formed complexes with actin monomer, inhibited actin polymerization and cross-linked to actin. All the results indicated BmTHY might be an actin-sequestering protein and participate in silkworm development.

Background: Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) is usually administered by injection, and its oral administration in a clinical setting has been not yet reported. Here we demonstrate the bioavailability of orally administered rhGM-CSF in healthy volunteers. The rhGM-CSF was expressed in Bombyx mori expression system (BmrhGM-CSF)., Methods and Findings: Using a single-dose, randomized, open-label, two-period crossover clinical trial design, 19 healthy volunteers were orally administered with BmrhGM-CSF (8 microg/kg) and subcutaneously injected with rhGM-CSF (3.75 microg/kg) respectively. Serum samples were drawn at 0.0h, 0.5h ,0.75h,1.0h,1.5h,2.0h ,3.0h,4.0h,5.0h,6.0h,8.0h,10.0h and 12.0h after administrations. The hGM-CSF serum concentrations were determined by ELISA. The AUC was calculated using the trapezoid method. The relative bioavailability of BmrhGM-CSF was determined according to the AUC ratio of both orally administered and subcutaneously injected rhGM-CSF. Three volunteers were randomly selected from 15 orally administrated subjects with ELISA detectable values. Their serum samples at the 0.0h, 1.0h, 2.0h, 3.0h and 4.0h after the administrations were analyzed by Q-Trap MS/MS TOF. The different peaks were revealed by the spectrogram profile comparison of the 1.0h, 2.0h, 3.0h and 4.0h samples with that of the 0.0h sample, and further analyzed using both Enhanced Product Ion (EPI) scanning and Peptide Mass Fingerprinting Analysis. The rhGM-CSF was detected in the serum samples from 15 of 19 volunteers administrated with BmrhGM-CSF. Its bioavailability was observed at an average of 1.0%, with the highest of 3.1%. The rhGM-CSF peptide sequences in the serum samples were detected by MS analysis, and their sizes ranging from 2,039 to 7,336 Da., Conclusions: The results demonstrated that the oral administered BmrhGM-CSF was absorbed into the blood. This study provides an approach for an oral administration of rhGM-CSF protein in clinical settings., Trial Registration: www.chictr.orgChiCTR-TRC-00000107.

Avian influenza virus (H5N1) has caused serious infections in human beings. This virus has the potential to emerge as a pandemic threat in humans. Effective vaccines against H5N1 virus are needed. A recombinant Bombyx mori baculovirus, Bmg64HA, was constructed for the expression of HA protein of H5N1 influenza virus displaying on the viral envelope surface. The HA protein accounted for approximately 3% of the total viral proteins in silkworm pupae infected with the recombinant virus. Using a series of separation and purification methods, pure Bmgp64HA virus was isolated from these silkworm pupae bioreactors. Aluminum hydroxide adjuvant was used for an H5N1 influenza vaccine. Immunization with this vaccine at doses of 2 mg/kg and 0.67 mg/kg was carried out to induce the production of neutralizing antibodies, which protected monkeys against influenza virus infection. At these doses, the vaccine induced 1:40 antibody titers in 50% and 67% of the monkeys, respectively. The results of safety evaluation indicated that the vaccine did not cause any toxicity at the dosage as large as 3.2 mg/kg in cynomolgus monkeys and 1.6 mg/kg in mice. The results of dose safety evaluation of vaccine indicated that the safe dose of the vaccine were higher than 0.375 mg/kg in rats and 3.2 mg/kg in cynomolgus monkeys. Our work showed the vaccine may be a candidate for a highly effective, cheap, and safe influenza vaccine for use in humans.