Dvorah Diminsky

Comparison between hepatitis B surface antigen (HBsAg) particles derived from mammalian cells (CHO) and yeast cells (Hansenula polymorpha): Composition, structure and immunogenicity

The composition, structure and immunogenicity of hepatitis B surface antigen (HBsAg) particles derived from Chinese hamster ovary (CHO) cells and from cells of the yeast Hansenula polymorpha were compared. The particles were similar in size distribution (mean 20-33 nm), in shape (spherical), in gross composition (protein to lipid weight ratio of 60:40), and in types of lipids (phospholipids > > sterols = sterol esters = triacylglycerols). Differences related to genetic engineering and type of host cells were found in peptide and lipid compositions. CHO-HBsAg has three peptides: S, M and L, each in two forms of glycosylation, while the Hansenula-HBsAg has only the nonglycosylated S peptide. The electrical surface potential at the lipid/water interface of HBsAg derived from Hansenula is more negative than that of HBsAg derived from CHO, which was close to neutrality. Although the numbers of cysteine residues (all in the S peptides) are identical (14), 11 of them are free thiols in the CHO-HBsAg, compared with three to four in the Hansenula-HBsAg. The fact that 85% of the phospholipids are hydrolyzed by phospholipase C and that all the aminophospholipids react with trinitrobenzenesulfate suggests that the particles derived from both cell types are either leaky vesicles or have a lipoprotein-like structure. Subcutaneous injection into mice of fluorescein-isothiocyanate-labeled HBsAg particles from both sources resulted in their accumulation in the marginal sinus of lymph nodes. The humoral responses to subcutaneous injection into mice of CHO- and Hansenula-HBsAg were similar: however, the cytotoxic T lymphocyte response to CHO-HBsAg was lower.

Structural and Functional Characterization of Liposomal Recombinant Hepatitis B Vaccine

AbstractLiposomal hepatitis B vaccine was prepared by encapsulating recombinant 22-nm hepatitis B surface antigen (HBsAg) particles derived from a Chinese hamster ovary (CHO) cell line in multilammelar lipid vesicles (MLV) composed of 9:1 dimyristoyl phosphatidyl-choline/dimyristoyl phosphatidylglycerol. The CHO-derived HBsAg particles reveal 6 bands in polyacrylamide gel electrophoresis related to the presence of 3 peptides (S, M, & L). Four different methods were used to prepare the MLV vaccine, each resulting in freeze-dried powder which upon hydration gave MLV of a similar mean size, 4.5 μm. The humoral response to these 4 liposomal vaccines in mice was dependent on the method of preparation, but for all of them it was better than the response to alum-based vaccine (especially at a low dose of antigen). Comparison of vaccination using “naked” HBsAg particles, particles adsorbed to alum, and particles encapsulated in liposomes demonstrated that at low dose of antigen the liposomal vaccine was superior ...

Surface Active Phospholipids as Cartilage Lubricants

Efficient lubrication and extremely low friction are essential for proper functioning of synovial joints. Various joint dysfunctions were described in direct association with increased friction or adhesive forces. Surface-active phospholipids (SAPLs) are well known to reduce friction in synovial joints. This study demonstrates, using a novel human-sourced cartilage-on-cartilage setup, the potential of multilamellar vesicles (MLV) composed of the SAPL dimyristoyl phosphatidylcholine (DMPC) to act as effective lubricants, reducing static and dynamic friction-coefficients to levels of healthy synovial joints. Furthermore, MLV composed of DMPC, in sizes ranging from 0.8 to ∼3.5 μm, were found to be more effective lubricants than histidine buffer, saline, or synovial fluid. The ability to test new cartilage lubricants, simulating, to a great extent, natural conditions, using the setup presented herein is discussed.Copyright