Most species of the genus
Bifidobacterium
contain the gene cluster PFNA, which is presumably involved in the species-specific communication between bacteria and their hosts. The gene cluster PFNA consists of five genes including
fn3
, which codes for a protein containing two fibronectin type III domains. Each fibronectin domain contains sites similar to cytokine-binding sites of human receptors. Based on this finding we assumed that this protein would bind specifically to human cytokines
in vitro
. We cloned a fragment of the
fn3
gene (1503 bp; 501 aa) containing two fibronectin domains, from the strain
B. longum
subsp.
longum
GT15. After cloning the fragment into the expression vector pET16b and expressing it in
E. coli
, the protein product was purified to a homogenous state for further analysis. Using the immunoferment method, we tested the purified fragment’s ability to bind the following human cytokines: IL-1β, IL-6, IL-10, TNFα. We developed a sandwich ELISA system to detect any specific interactions between the purified protein and any of the studied cytokines. We found that the purified protein fragment only binds to TNFα.
Introduction. The ability of SARS-CoV-2 antibodies to neutralize the virus is the primary indicator of their specific activity. The test for virus neutralizing antibodies (NAbs) is much needed in different biomedical studies.The aim of the study is to find optimum conditions for microscopic and spectrophotometric detection of SARSCoV-2 NAbs by inhibition of cytopathic effect (CPE) in cell cultures.Materials and methods. Blood sera collected from COVID-19 convalescent patients and healthy individuals (n = 96) were tested using the ELISA method. The SARS-CoV-2 coronavirus, Dubrovka strain (GenBank accession no. MW514307.1) was grown in culture medium of Vero cell line CCL-81 (ATCC). Real-time RT-PCR, ELISA, and Sanger sequencing were used for detection of the virus. The results of the neutralization test (NT) were assessed through the microscopic examination for CPE and by the methyl thiazolyl tetrazolium (MTT) assay.Results. SARS-CoV-2 was isolated from a COVID-19 patient and adapted to grow in cell culture. At a low dose of infection (MOI = 0.00001), the virus caused a pronounced CPE with the cell viability less than 3%, thus making it possible to assess NT results by CPE inhibition. The NT and ELISA-based comparative study of sera showed positive correlation between virus NAb titers and Nab titers to S-protein RBD (Spearman’s r = 0.714; p < 0.001). The results of NAbs microscopic and spectrophotometric detection (the MTT assay) also demonstrated positive correlation (Spearman’s r = 0.963; p < 0.05).Conclusion. The SARS-CoV-2 virus adapted to Vero cell culture served to develop a NAb titer assessment system, which can be used both in microscopic studies and for an MTT assay in spectrophotometric studies. The MTT assay provides automated reading of NT results, optimizes the statistical analysis of the obtained data, and minimizes subjectivity in assessment of results. Being a vital dye, MTT penetrates only viable cells, thus contributing to the reliability of the obtained results compared to other dyes.
Introduction. The increase in the incidence of whooping cough in children and adults of different age groups justifies the need for their revaccination and the development of new, acceptable for these purposes. This work is devoted to substantiating the design of a clinical trial and describing the results of a comparative study of the safety and tolerability of the drug "GamLPV" with two-fold intranasal administration to healthy adult volunteers using two methods. The choice of the scheme and method of administration of the drug is justified. The serological structure of the population of adults aged 18–40 years living in Moscow and the Moscow region is characterized.Aim. Determination of the safety and tolerability of the drug with a double intranasal administration of the vaccine by drip method and spraying through an actuator.Materials and methods. A randomized placebo-controlled trial included 50 healthy male and female volunteers aged 18 to 40 years who met the inclusion criteria. The volunteers were divided into 2 groups of 25 people: a drip method of administration and spraying through an "actuator". By both methods, the drug was administered twice with an interval of 60 days.Results and discussion. Serological analysis of the population of healthy volunteers at the prescreening stage justified the inclusion in the study of volunteers containing anti-pertussis antibodies in the blood (IgG ≤40 Ed/ml). A comparison of the results of preclinical studies on an experimental model of non-human monkeys and the first phase of a clinical study of GamLPV allowed us to propose two methods of double administration of the drug as a promising vaccination scheme for volunteers. A comparative randomized study shows the safety of using the proposed scheme for vaccination of adult volunteers.Conclusions. Both proposed methods of double administration can be used to plan a multicenter study to research the immunogenicity and protective activity of GamLPV.
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