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.

Dynamics of Antibodies to Various Antigens of the SARS-CoV-2 Coronavirus in Patients with Confirmed COVID-19 Infection.

The presence of IgG and IgM antibodies in the venous blood of 76 patients with confirmed COVID-19 infection was determined by ELISA using Russian test systems. Different levels of IgM antibodies to N-protein and receptor binding domain of the Spike protein (RBD) were revealed. The dynamics of IgG antibodies to the whole virion antigen and recombinant antigens showed high values on weeks 4-5 of the disease. The level of IgG antibodies to Nprotein remained low throughout the observation period. The characteristic dynamics of IgG measured using test systems with sorbed whole virion or recombinant spike proteins reflects the duration of the disease.

[Definitionof anti-pertussis antibodies by immunoassay.]

Comparative analysis of efficiency of identification the anti-pertussis of antibodies of three classes (IgM, IgG, IgA) by means of four commercial test systems used for serological diagnosis of whooping cough in the Russian Federation by RIDASCREEN (R-Biohharm AG, Германия), NOVATEC (Immunodiagnostica GmbH, Germany), DRG Diagnostics (Germany), Savyon Diagnostics (Israel) is carried out. The research included 42 serums of blood of the children and adults with whooping cough hospitalized in Infectious diseases clinical hospital No. 1 of the Moscow Department of Healthcare. In work the commercial test systems - RIDASCREEN (r-Biofarm, Germany), NOVATEC (Germany), DRG (Germany), Savyon (Israel) are used, according to instructions of producers. Complete coincidence of results of a research is established in 40,5% cases, in 42,9% not complete coincidence of results on dynamics of development of one class of antibodies is revealed and in 9,5% cases the discrepancy of results on two classes of antibodies is revealed. In total discrepancies of results - 7,1%. At determination of antibodies of the class IgM in serum of blood of patients with whooping cough the greatest number of positive results is defined in the SAVYON - 83,3±6,3% (35 serums), NOVATEC - 71,4±8,2% (30 serums), RIDASCREEN - 61,9±9,7% (26 serums), DRG - 45,2±11,7% (19 serums). Class IgG antibodies in all test systems were defined at one level. Some distinctions took place in determination of IgA. The high percent of identification of IgA was in the RIDASCREEN - 59,5±10,0% (25 serums) and DRG - 50,0±11,2% (21 serums). In the NOVATEC and SAVYON this percent was lower - 45,2±11,7% and 26,2±13,9%, respectively (19 and 11 serums). Thus, the research showed that for serological researches any of these 4 test systems can be used. It is recommended to conduct diagnostic testings of serums of blood in one chosen test system for obtaining comparable results and to interpret the results received in one test system when obtaining doubtful results it is necessary to investigate serums in dynamics at the same time in one test system.

[The development of Endo growth medium for detection and identification of enterobacteria.]

The purpose of study is to develop a traditional Endo's growth medium with the view of suppression of swarming of Proteus vulgaris and Proteus mirabilis. The object of study was a commercial dry Endo's growth medium. The inoculation of reference strains of enterobacteria and clinical sample (feces, urine, phlegm) was implemented according the normative documents. It is demonstrated that brining into Endo's growth medium tryptophan and sodium salts of bile acids in a particular ratio of their concentrations suppressed swarming of Proteus vulgaris and Proteus mirabilis. The obtained results demonstrated that application of enhanced Endo's growth medium significantly increases its differential and diagnostic characteristics.