SUMMARYAspergillus fumigatus, a ubiquitous fungus, is implicated in the pathogenesis of a number of clinically different allergic diseases in man, including allergic broncopulmonary aspergillosis. Peptide-based immunotherapy may offer an alternative treatment strategy for the management of allergic disease. The objective of this study was to alter the allergen-specific immune response using dominant T cell epitopes of a major A. fumigatus allergen, Asp f2, expressed in yeast as virus-like particles (VLP). The T cell epitopes of Asp f2, recognized in mice with an H-2 d background, were determined by producing T-cell hybridomas. Two dominant T cell epitopes, aa60-71 and aa235-249, were identified and expressed in a yeast VLP system. To induce tolerance VLP-peptides were injected subcutaneously into mice previously immunized with recombinant Asp f2. The T cell immune response was abrogated totally in 3 weeks following a single injection of VLP but was restored 2 months later following intranasal antigen exposure. T-cell depletion resulted in the reduction of 20-30% of all antigen-specific immunoglobulin classes. Thus, recombinant peptides expressed in the VLP system can be used successfully in the modulation of Asp f2-induced immune response in mice, although a single administration is not sufficient to maintain a state of tolerance for a long period of time.
Virus-like particles (VLPs) containing heterologous proteins are often used as vaccines. Two approaches for the construction of bi-functional VLPs using hybrid protein pl-380 of the Ty1 transposon of Saccharomyces yeast are described. We have shown that both C- and N-termini of p1–380 can be used for the expression of heterologous peptides. Peptides from A. fumigatus Asp f 2, expressed at the C- and/or N-termini of p1–380, did not interfere with VLP self-assembling, were accessible for antibodies and hence were exposed at the VLP surface. Another way to obtain bivalent VLPs is the formation of mixed particles, which co-express two hybrid pl proteins with different heterologous protein fragments at the C-terminus. To do it the yeast cells were transfected with a mixture of two recombinant DNA coding Asp f 2 peptide and green fluorescent protein (Gfp). We have shown that both Asp f 2 peptide and Gfp are expressed within the same particle. To evaluate biological activity of bi-functional VLP a construction containing peptides representing dominant T- and B-cell epitopes of Asp f 2 was produced. Bi-functional particles were more potent in stimulating memory immune responses. These results demonstrate new possibilities of pl-380 based expression system to produce multifunctional VLPs.
Sub-unit vaccines are synthetic or recombinant peptides representing T- or B-cell epitopes of major protein antigens from a particular pathogen. Epitope selection requires the synthesis of peptides that overlap the protein sequences and screening for the most effective ones. In this study a new method of immunogenic peptide selection based on the analysis of information structure of protein sequences is suggested. The analysis of known B-cell epitope location in the information structure of Aspergillus fumigatus proteins Asp f 2 and Asp f 3 has shown that epitopes are scattered along the sequences of proteins for the exception of sites with Increased Degree Information Coordination (IDIC). Based on these results peptides from different allergens such as Asp f 2, Der p 1, and Fel d 1 were selected and produced in a recombinant form in the context of yeast virus-like particles (VLPs). Immunization of mice with VLPs containing peptides form allergens has induced the production of IgG able to recognize full-length antigens. This result suggests that the analysis of information structure of proteins can be used for the selection of peptides possessing cryptic B-cell epitope activity.
The paper presents analysis of the structure of HIV-infected persons at different stages of the development of the HIV epidemic process in the Tyumen region (no autonomous areas) from the moment of the first case registration until 2018. We used descriptive-evaluative, analytical, statistical and epidemiological research methods taking into account intensive and extensive indicators, the structure of HIV-infected persons, the identification of trend in the epidemic process. Analysis of the long-term and intra-annual dynamics of the morbidity and prevalence of HIV infection in the Tyumen region clearly showed that the epidemiological situation in the region is alarmingly tense, but the concentration of health authorities and the sanitary-epidemiological service have already yielded positive results in this direction.
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