Interaction of wild-type and naturally occurring deleted variants of hepatitis B virus core polypeptides leads to formation of mosaic particles.

The simultaneous presence of hepatitis B virus (HBV) genomes carrying wild-type (wt) and in-frame deleted variants of the HBV core gene has been identified as a typical feature of HBV-infected renal transplant patients with severe liver disease. To investigate possible interactions of wt and deleted core polypeptides a two-vector Escherichia coli expression system ensuring their concomitant synthesis has been developed. Co-expression of wt and a mutant core lacking 17 amino acid residues (77-93) within the immunodominant region led to the formation of mosaic particles, whereas the mutant alone was incapable of self-assembly.

Mosaic Qbeta coats as a new presentation model.

The new protein carrier was developed on the basis of recombinant RNA phage Qbeta capsid. C-terminal UGA extension of the short form of Qbeta coat, so-called A1 extension, served as a target for presentation of foreign peptides on the outer surface of mosaic Qbeta particles. In conditions of enhanced UGA suppression, the proportion of A1-extended to short coats in mosaic particles dropped from 48% to 14%, with an increase of the length of A1 extension. A model insertion, short preS1 epitope 31-DPAFR-35 of hepatitis B surface antigen, demonstrated superficial location on the mosaic Qbeta particles and ensured specific antigenicity and immunogenicity.

New chimaeric hepatitis B virus core particles carrying hantavirus (serotype Puumala) epitopes: immunogenicity and protection against virus challenge.

Virus-like particles generated by the heterologous expression of virus structural proteins are able to potentiate the immunogenicity of foreign epitopes presented on their surface. In recent years epitopes of various origin have been inserted into the core antigen of hepatitis B virus (HBV) allowing the formation of chimaeric HBV core particles. Chimaeric core particles carrying the 45 N-terminal amino acids of the Puumala hantavirus nucleocapsid protein induced protective immunity in bank voles, the natural host of this hantavirus. Particles applied in the absence of adjuvant are still immunogenic and partially protective in bank voles. Although a C-terminally truncated core antigen of HBV (HBcAg delta) tolerates the insertion of extended foreign sequences, for the construction of multivalent vaccines the limited insertion capacity is still a critical factor. Recently, we have described a new system for generating HBV 'mosaic particles' in an Escherichia coli suppressor strain based on a readthrough mechanism on a stop linker located in front of the insert. Those mosaic particles are built up by both HBcAg delta and the HBcAg delta/Puumala nucleocapsid readthrough protein. The particles formed presented the 114 amino acid (aa) long hantavirus sequence, at least in part, on their surface and induced antibodies against the hantavirus sequence in bank voles. Variants of the stop linker still allowed the formation of mosaic particles demonstrating that stop codon suppression alone is sufficient for the packaging of longer foreign sequences in mosaic particles. Another approach to increase the insertion capacity is based on the simultaneous insertion of different Puumala nucleocapsid protein sequences (aa 1-45 and aa 75-119) into two different positions (aa 78 and behind aa 144) of a single HBcAg molecule. The data presented are of high relevance for the generation of multivalent vaccines requiring a high insertion capacity for foreign sequences.

Evaluating a 'non-diet' wellness intervention for improvement of metabolic fitness, psychological well-being and eating and activity behaviors.

CONTEXT: Current public health policy recommends weight loss for obese individuals, and encourages energy-restricted diets. Others advocate an alternative, 'non-diet' approach which emphasizes eating in response to physiological cues (eg hunger and satiety) and enhancing body acceptance. OBJECTIVE: To evaluate the effects of a 'health-centered' non-diet wellness program, and to compare this program to a traditional 'weight loss-centered' diet program. DESIGN: Six-month, randomized clinical trial. SETTING: Free-living, general community. PARTICIPANTS: Obese, Caucasian, female, chronic dieters, ages 30-45 y (n=78). INTERVENTIONS: Six months of weekly group intervention in a non-diet wellness program or a traditional diet program, followed by 6 months of monthly after-care group support. OUTCOME MEASURES: Anthropometry (weight, body mass index); metabolic fitness (blood pressure, blood lipids); energy expenditure; eating behavior (restraint, eating disorder pathology); psychology (self-esteem, depression, body image); attrition and attendance; and participant evaluations of treatment helpfulness. Measures obtained at baseline, 3 months, 6 months and 1 y. RESULTS: (1 y after program initiation): Cognitive restraint increased in the diet group and decreased in the non-diet group. Both groups demonstrated significant improvement in many metabolic fitness, psychological and eating behavior variables. There was high attrition in the diet group (41%), compared to 8% in the non-diet group. Weight significantly decreased in the diet group (5.9+/-6.3 kg) while there was no significant change in the non-diet group (-0.1+/-4.8 kg). CONCLUSIONS: Over a 1 y period, a diet approach results in weight loss for those who complete the intervention, while a non-diet approach does not. However, a non-diet approach can produce similar improvements in metabolic fitness, psychology and eating behavior, while at the same time effectively minimizing the attrition common in diet programs.

RNA phage Q beta coat protein as a carrier for foreign epitopes.

The Q beta gene C has been proposed as a new carrier for the exposure of foreign peptide sequences. Contrary to well-known 'display vectors' on the basis of coat proteins of RNA phage group I, group III phage Q beta-based vectors suggested application of the 195-amino acid extension of coat protein (CP) within the so-called A1 protein for insertion of the appropriate immunological epitopes. 'Mosaic' capsids presenting model hepatitis B virus preS1 and HIV-1 gp120 epitopes and formed by Q beta CP together with A1-derived proteins were obtained as a result of (1) suppression of leaky UGA stop codon of the CP gene and (2) simultaneous expression of 'pure' CP and full-length A1-derived genes obtained after the changing of CP-terminating UGA to strong UAA stop codon or sense GGA codon, respectively.