Features of the Humoral Response to Infection, Vaccination, and Revaccination during COVID-19.

IgM and IgG antibodies to the SARS-CoV-2 virus are detected in subjects who have recovered from COVID-19; IgM antibodies persist in a 1/3 of infected subjects up to 12 months from the moment of the disease, while IgG antibodies are present in the vast majority of cases (97%; medium and high levels antibodies were registered in 85% of cases). By the 12th month, 40% of those who recovered still have a very high level of IgG antibodies to the S-protein (>500 BAU/ml). In the feces, urine, and blood serum of patients with long-term persistent IgM antibodies, no coronavirus antigens were detected. After vaccination with the Gam-COVID-Vac vaccine, IgG antibodies to the S-protein are detected in 100% of cases and remain at a high level for 4 months, by the 5-6th month, the level of antibodies decreases. During revaccination, the level of IgG antibodies to S-protein reaches high values earlier than during primary vaccination, and remains high for 4 months (observation period). The blood sera of recovered and vaccinated patients have a high virus-neutralizing activity (at least 1:80), while its level is somewhat higher in recovered patients.

Development of accelerated genodiagnosis method of pertussis and pertussis-like diseases on the basis of mPCR-RT.

The aim of the work was to develop an accelerated genodiagnosis method based on mPCR-RT for the detection DNA of B. pertussis, B. parapertussis, B. holmesii. MATERIALS AND METHODS: The study used 104 strains of microorganisms, of which: 50 strains of B. pertussis, 37 - B. parapertussis, 17 - heterologous species of microorganisms. Assessment of analytical specificity was carried out using DNA strains of various microorganisms with a concentration at least 109 GE / ml. To check the analytical sensitivity we studied a series of serial dilutions of bacterial cultures of the control strains B. pertussis № 143, B. parapertussis № 38b, B. holmesii DSM 13416 with a concentration of 5x109 - 5 µm/ml. RESULTS: Insertion sequences were chosen as diagnostic targets: for B. parapertussis - a specific fragment IS1001, for B. holmesii - a specific fragment hlIS1001, for B.pertussis - a fragment IS481. To develop a genodiagnosis method specific primers were designed and combined into a single multi-primer mixture, the composition of the reaction mixture and the amplification conditions were selected. The analytical sensitivity of the developed method for detecting pertussis and pertussis-like pathogens was 5×101 GE / ml. Verification of the developed methodology of gene diagnostics showed 100% analytical specificity. CONCLUSION: An accelerated genodiagnosis method based on mPCR-RT has been developed, it allows you to identify DNA of B. pertussis, B. parapertussis, B. holmesii, which expands the possibilities of examining patients with suspected pertussis and pertussis-like diseases in order to increase laboratory confirmation of the diagnosis.

[Efficacy of laboratory methods of diagnostic of purulent bacterial meningitis.]

According to the World Health Organization, every year about 1 million cases of purulent bacterial meningitis (PBM) are registered in the world, of which 200 thousand cases end in death. Bacterial meningitis is polyethiologic, which makes the task of determining the pathogen the main in the organization of epidemiological surveillance, treatment regimens, planning of preventive and anti-epidemic measures. The quality of laboratory diagnostics has a key influence on this. The true incidence of meningitis of different etiology can be altered at low-efficiency laboratory diagnostics. This work was carried out to assess the effectiveness of existing laboratory methods for the detection of PBM pathogens: Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis; as a part of the programme on sentinel surveillance of invasive bacterial diseases (IBD) carried out by the WHO regional office for Europe in a number of countries in Europe (Ukraine, Belarus), Transcaucasia (Azerbaijan, Armenia, Georgia), Asia (Uzbekistan, Kyrgyzstan, Kazakhstan) in the period 2010-2017. 2893 samples of clinical material (CSF and blood) obtained from patients with the meningeal syndrome were studied by four diagnostic methods: cultural method, latex-agglutination test, immunochromatographic test (BinaxNOW), PCR (conventional and real-time), used to identify the following pathogens: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae. When identifying the causative agents of BM, PCR more effective than culture method is 5 times in detecting N. meningitidis; 3 times in the detection of S. pneumoniae; 4 times the detection of H. influenzae b. Latex-agglutination test and immunochromatographic test allow to increase the identification of pathogens of BM for N. meningitidis - by 35.6%; S. pneumoniae - by 67%; H. influenzae b - by 19.2%, it is possible to set them in the field and at the epidpoint if necessary. When working with clinical material from patients diagnosed with GBM, it is advisable for bacteriological laboratories to complement the culture method of microbiological diagnosis of latex-agglutination test, immunochromatographic test or PCR.