0000000000117880
AUTHOR
Juris Jansons
Signal sequences modulate the immunogenic performance of human hepatitis C virus E2 gene
Abstract Envelope protein E2 of human hepatitis C virus (HCV) is an attractive component of a prototype HCV vaccine. Delivered by DNA immunogens, E2 evokes specific immune response of Th1-type, failing to induce either considerable antibody production, or T-helper cell proliferation. We aimed at modulating the immunogenic performance of E2 gene by changing the mode of protein expression in eukaryotic cells. Plasmids were constructed encoding full-length E2 and nonstructural protein 1 (p7) fused to either 13 or 38 C-terminal amino acids (aa) of HCV E1 that contain second hydrophobic segment of E1 stop-transfer signal, or a complete E1 stop-transfer signal with duplicated second hydrophobic s…
An outbreak of HBV and HCV infection in a paediatric oncology ward: Epidemiological investigations and prevention of further spread
Hospital-acquired hepatitis B (HBV) and C virus (HCV) infections continue to occur despite increased awareness of this problem among the medical community. One hundred six patients were infected in a haematology oncology ward for children, over the time period 1996 to 2000. Serum samples from 45 such patients and 3 from infected medical personnel were used for nucleic acid amplification. HBV core, as well as HCV core and hypervariable region 1 (HVR1) nucleotide sequences, were analysed by phylogenetic tree analysis, in order to characterise the epidemiological pattern of viral transmission on the ward. Samples from 32 patients were positive for HBV-DNA or HCV-RNA by PCR. Ten patients were p…
Mechanical properties of pultruded glass fiber-reinforced plastic after moistening
Abstract The kinetics of moisture sorption under immersion in water at room and elevated temperatures and flexural characteristics of dry (conditionally initial) and wet (moistened up to saturation level) composite material were investigated on flat specimens of polyester based glass fiber-reinforced plastic, cut from I-beam pultruded profile. It was found that the coefficients of diffusion and swelling are different in three principal axis of the composite. The former have the largest value in fiber axis direction, but the latter – in transverse to fiber axis direction out of plane of the layers. The observed difference in kinetics of mass gain and change of volume strain for the specimens…
Hepatitis B and C virus variants in long-term immunosuppressed renal transplant patients in Latvia.
The incidence of genome variants of hepatitis B and hepatitis C viruses among 38 long-term (2–15 years) immunosuppressed patients after renal transplantation and 10 patients undergoing dialysis was investigated. Twelve patients had only HBV infection, 9 had only HCV infection and 14 were co-infected. Regions corresponding to the HBV X/EnII/BCP, preC/C, preS/S and to the HCV core were sequenced for molecular characterization of the HBV and HCV genomes. Fifty-seven percent of HBV DNA isolates belonged to genotype D and 42% to genotype A, whereas 77% of HCV RNA isolates belonged to genotype 1b and only 17% to genotype 3a. One sample (6%) was of genotype 2c. Detailed analysis of the above-menti…
Drošības risinājumi, izmantojot Android ierīces
Darba ietvaros autors aplūkoja uz šo brīdi populārākās mobilo ierīču operētājsistēmas Android drošības risinājumus, kurus iespējams ieviest papildus operētājsistēmas esošajiem risinājumiem, lai palielinātu datu drošību šajās ierīcēs. Darbā autors aplūkojis jau pieejamus risinājuma aprakstus, kā arī aprakstījis savu ideju par datu drošības palielināšanu ierīcē.
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Encapsulation mechanisms and structural studies of GRM2 bacterial microcompartment particles
Bacterial microcompartments (BMCs) are prokaryotic organelles consisting of a protein shell and an encapsulated enzymatic core. BMCs are involved in several biochemical processes, such as choline, glycerol and ethanolamine degradation and carbon fixation. Since non-native enzymes can also be encapsulated in BMCs, an improved understanding of BMC shell assembly and encapsulation processes could be useful for synthetic biology applications. Here we report the isolation and recombinant expression of BMC structural genes from the Klebsiella pneumoniae GRM2 locus, the investigation of mechanisms behind encapsulation of the core enzymes, and the characterization of shell particles by cryo-EM. We …
The effect of partial exfoliation of multilayer silicate filler particles on the elastic properties of a polymer composite
Abstract A method for stepwise calculation the elastic constants of a three-phase composite, including the polymer matrix, the fully exfoliated silicate nanolayers and the platelike silicate particles in the form of multilayer intercalated stacks is considered. A theoretical analysis is carried out by using the Mori–Tanaka theory of an equivalent medium. The influence of degree of exfoliation (the ratio of exfoliated filler content to the total filler content) on the reinforcing efficiency is studied and discussed. A comparative analysis of experimental data of elastic modulus for a rigid polyurethane/montmorillonite composite and prediction results is carried out. It is shown, that with gr…
N‐Terminal Modification of Gly‐His‐Tagged Proteins with Azidogluconolactone
Site-specific protein modifications are vital for biopharmaceutical drug development. Gluconoylation is a non-enzymatic, post-translational modification of N-terminal HisTags. We report high-yield, site-selective inâ vitro α-aminoacylation of peptides, glycoproteins, antibodies, and virus-like particles (VLPs) with azidogluconolactone at pHâ 7.5 in 1â h. Conjugates slowly hydrolyse, but diol-masking with borate esters inhibits reversibility. In an example, we multimerise azidogluconoylated SARS-CoV-2 receptor-binding domain (RBD) onto VLPs via click-chemistry, to give a COVID-19 vaccine. Compared to yeast antigen, HEK-derived RBD was immunologically superior, likely due to observed diffe…
Evaluation of HBs, HBc, and frCP virus-like particles for expression of human papillomavirus 16 E7 oncoprotein epitopes.
<i>Objectives:</i> In an attempt to develop virus-like particles (VLPs) as experimental vaccine against human papilloma virus (HPV)-induced tumours, the HPV16 E7 oncoprotein epitopes spanning amino acid (aa) residues 35–98 were expressed on three proteins capable of VLP formation: hepatitis B virus (HBV) surface (HBs) and core (HBc) antigens, and RNA phage fr coats (frCP). <i>Methods:</i> The profile of immunoglobulin isotypes induced in Balb/C mice after immunization with purified chimeric proteins was studied. <i>Results:</i> The HBs*-E7(35–54) protein expressing E7 residues 35–54 between residues 139 and 142 of the HBs carrier formed HBs-like particles…
Fine-mapping of the B-cell epitope domain at the N-terminus of the preS2 region of the hepatitis B surface antigen
In this study, we report the exact localization and substitutional characterization of a B-cell epitope domain at the N-terminus of the preS2 region of the hepatitis B surface antigen. A set of deletion variants containing preS2 sequences of different length was generated on the basis of frCP as a carrier. It was found after Western blot analysis that three monoclonal antibodies (MAbs) (2-11B1, 3-11C2, HB.OT10) recognized the linear preS2 sequence within the amino acid (aa) stretch 3-WNSTTFHQTLQDP-13. The importance of each aa residue of the epitope was proved by comparison of antibody binding to alanine-substituted peptides in both free-peptide and Pepscan variants.