The HIV-1 capsid protein (CA) plays an essential role in viral core assembly and maturation. Proteolytic cleavage at the MA-CA junction of the retroviral gag polyprotein refolds the amino-terminal end of capsid into a beta-helix structure that is stabilized by a salt bridge between the protein's processed amino-terminus and a conserved acidic residue. The refolded capsid aminoterminus then creates a new CA-CA interface, allowing assembly of the mature capsid core. Recently, researches focus on assembly of CA in vitro and development of CA vaccine. CA vaccine will provide widely immune protection because CA is comparatively conserved. Experiments demonstrate that fusing as few as four matrix residues onto the amino-terminus of capsid redirects protein assembly from cylinder to spheres in vitro. Evaluation of immunogenicity showed that immunization with virus-like particles induced both cellular and neutralizing antibody responses. Furthermore, mucosal administration of virus-like particles effectively induced both mucosal and systemic immune responses. These results indicate that virus-like particles consisting of HIV structural proteins are an attractive vaccine platform for eliciting anti-viral immune responses, especially neutralizing antibody responses. The production of antigens for vaccines in plants indicates that plant-based transgenic expression represents a viable means of producing CA vaccine for the development of HIV vaccine and for use in HIV diagnostic procedures and it has the potential as a safe and cost-effective alternative to traditional production systems.
AIDS Vaccines ; immunology ; Capsid ; immunology ; metabolism ; Capsid Proteins ; genetics ; immunology ; metabolism ; HIV-1 ; genetics ; immunology ; metabolism ; Virion ; genetics ; immunology ; metabolism

BACKGROUND: The dramatic increase in use of the IgG test for toxoplasma, rubella, cytomegalovirus (CMV), and herpes simplex virus (HSV) [TORCH] has led to the requirement for a high-efficiency method that can be used in the clinical laboratory. This study aimed to compare the results of BGI-Array ELISA TORCH IgG (BGI-GBI, China) screening method to those of Virion/Serion TORCH IgG ELISA (Virion/Serion, Germany). METHODS: Serum specimens (n=400) submitted for routine IgG testing by Virion/Serion ELISA were also tested using the BGI-Array ELISA method. The agreements of these two kinds of method were analyzed by kappa-coefficients calculation. RESULTS: Following repeat testing, the BGI-Array ELISA TORCH IgG assays demonstrated agreements of 99.5% (398/400 specimens), 98% (392/400 specimens), 99% (396/400 specimens), and 99.5% (398/400 specimens), respectively. The BGI-Array ELISA IgG assays provided results comparable to Virion/Serion ELISA results, with kappa-coefficients showing near-perfect agreement for the HSV (kappa=0.87), rubella (kappa=0.92) and CMV (kappa=0.93) and substantial agreement for the toxoplasma (kappa=0.80) IgG assays. The use of the BGI-Array ELISA TORCH IgG assays could reduce the turnaround time (1.5 hr vs. 5 hr by Virion/Serion ELISA for 100 specimens) and were easy to use. CONCLUSIONS: BGI-Array ELISA TORCH IgG shows a good agreement with Virion/Serion ELISA methods and is suitable for clinical application.
Antibodies, Viral/blood ; Cytomegalovirus/immunology/*metabolism ; *Enzyme-Linked Immunosorbent Assay ; Humans ; Immunoglobulin G/*analysis/blood ; Protozoan Infections/diagnosis ; Reagent Kits, Diagnostic ; Rubella virus/immunology/*metabolism ; Sensitivity and Specificity ; Simplexvirus/immunology/*metabolism ; Toxoplasma/immunology/*metabolism ; Virion/*immunology/metabolism ; Virus Diseases/diagnosis

Here, we presented a method to bacterially express the major structural protein L1 of Human Papillomavirus type 18 (HPV18) as soluble form. We found that the purified L1 could self-assemble to virus-like particles (VLPs). Further, we investigated the immunogenicity and the induced level of neutralizing antibody using these VLPs. First, the genome of HPV18 was cloned from a patient in Xiamen. It was used as template for PCR amplification of HPV18 L1 gene. The resultant DNA fragment was inserted into expression vector pTrxFus and expressed in Escherichia coli GI724. Second, L1 protein was purified by ammonium sulfate precipitation, ion-exchange chromatography and hydrophobic interaction chromatography; and the purified L1 was subjected to self-assembly to form VLPs with the removal of premixed reductant DTT. Finally, the size and morphology of these VLPs was investigated by Dynamic Light Scattering and Transmission Electronic Microscopy as 29.34 nm in hydrated radius and globular particles similar with native HPV18. The half effective dosage (ED50) and maximum level of neutralizing antibody elicitation were measured by vaccinations on mice, rabbit and goat using pseudovirus neutralization cell model. The results showed that the ED50 of HPV18 VLPs is 0.006 microg in mice, and the maximum titer of neutralizing antibody elicited in rabbit and goat is up to 10(7). As a conclusion, we can provide HPV18 VLPs with highly immunogenicity from prokaryote expression system, which may pave a new way for research and development of prophylactic vaccine for HPV18.
Animals ; Capsid Proteins ; biosynthesis ; genetics ; immunology ; Escherichia coli ; genetics ; metabolism ; Goats ; Human papillomavirus 18 ; immunology ; isolation & purification ; Mice ; Oncogene Proteins, Viral ; biosynthesis ; genetics ; immunology ; Rabbits ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Virion ; genetics ; immunology

The baculovirus expression system was employed to prepare the virus-like particles (VLPs) of human parvovirus B19. The synthesized VP2 gene of B19 was inserted into the multi-cloning site (MCS) of pFastBac1 vector; the resulting plasmid was transferred to the Escherichia coli DH10Bac competent cells, which contain a baculovirus shuttle vector (Bacmid), to generate Bacmid-VP2 by site-specific transposition. Recombinant baculovirus carrying VP2 gene (rBac-VP2) was then rescued from Bacmid-VP2-transfected Sf9 cells. Indirect immunofluorescence and Western blotting were used to identify the VP2 protein in rBac-VP2-infected Sf9 cells, and the VLPs were observed under transmission electron microscope after being enriched by ultracentrifugation. The B19 VLPs were successfully produced in insect cells with baculovirus expression system, which will facilitate the development of diagnostic reagents to detect the antibody against B19 virus in human serum.
Animals ; Antibodies, Viral ; blood ; Baculoviridae ; genetics ; metabolism ; Capsid Proteins ; biosynthesis ; genetics ; Cell Line ; Cloning, Molecular ; Genetic Vectors ; genetics ; Parvovirus B19, Human ; genetics ; immunology ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification ; Virion ; genetics ; metabolism

To prepare carboxyl terminus truncated human papillomavirus type 58 L1 (HPV58L1) protein and evaluate its ability to form virus-like particles, the baculovirus and Sf-9 insect cells was used to express HPV58L1 protein, and pFastBac-Htb containing HPV58L1 gene sequence of carboxyl terminus truncation was generated. Then Sf-9 cells were infected with recombinant baculovirus. After being cultured, the post-infected cells expressing--HPV58L1 protein were harvested and analyzed by SDS-PAGE and Western blot. The ProBond purification system was used for protein purification. The bio-activity of purified protein was identified by mouse erythrocyte hemagglutination assay, and the VLP formation was examined with transmission electron microscope. Our results showed that the recombinant baculovirus was generated and the Sf-9 cells was infected with the recombinant baculovirus, and after collecting, total cellular proteins were extracted. Truncated HPV58L1 protein with MW 58KD was revealed by SDS-PAGE and confirmed by Western blot. The purified L1 proteins under native condition could cause mouse erythrocytes to agglutinate and form VLP. It is concluded that HPV58L1 protein with carboxyl terminus truncation could be efficiently expressed. In baculovirus Sf-9 cells expression system, the purified protein could self-assemble into virions in vitro, and induce agglutination of mouse erythrocytes, indicating that carboxyl terminus truncation does not interfere with the bioactivity of HPV58L1 protein.
Baculoviridae ; genetics ; metabolism ; Capsid Proteins ; Carbon Dioxide ; Humans ; Inclusion Bodies, Viral ; ultrastructure ; Oncogene Proteins, Viral ; biosynthesis ; genetics ; immunology ; Papillomaviridae ; physiology ; Recombinant Proteins ; biosynthesis ; Virion ; growth & development ; physiology ; Virus Assembly