Development of the ELISA Test System for Quantitative Determination of IgG to the Varizella zoster virus in Human Serum and Assessment of its Diagnostic Efficiency

Relevance. The introduction of Varicella vaccine prophylaxis explains the need to develop a methodology for monitoring the vaccination effectiveness and the intensity of population immunity. This problem can be solved using quantitative immunoassay methods. Aim. Development of an enzyme-linked immunosorbent assay for the concentration of class G immunoglobulins (AB) to Varicella zoster virus (VZV) determining and assessing its functional characteristics and diagnostic efficiency. Materials and methods. Recombinant antigen GE VZV. WHO International Standard for Antibodies to VZV W1044. Blood serum samples from healthy people and patients with Chickenpox and Herpes zoster, blood serum samples containing IgG antibodies to herpes simplex viruses of the first and second types, cytomegalovirus, Epstein-Barr virus. Anti-VZV ELISA (IgG) reagent kit (Euroimmun, Germany). Indirect enzyme-linked immunosorbent assay. Immunization of animals with recombinant antigen GE, isolation, and purification of specific antibodies. Conjugation of monoclonal antibodies to human IgG with antibodies to antigen GE and with horseradish peroxidase. Results. An enzyme-linked immunosorbent assay in «an indirect» format has been developed to determine the specific antibodies to VZV concentration (IU/ml) in human serum/plasma. An artificial calibrator for determining the concentration of AB-VZV had been synthesized and standardized according to the International WHO-standard W1044. The main functional characteristics of the developed enzyme-linked immunosorbent assay are determined in accordance with GOST 51352-2013. The diagnostic kit was tested on blood serum samples from children with chickenpox (n = 43), adults with Herpes zoster (n = 158), healthy individuals (n = 781). The diagnostic sensitivity of the test system was 85%, the diagnostic specificity was 87% according to the ROC analysis. The absence of cross-reactivity of the test system was shown on samples with serological markers of other herpesvirus infections (n = 94). Comparative trials of the developed test system and its commercial analog, the Anti-VZV ELISA (IgG) reagent kit, did not reveal statistically significant differences between their functional characteristics. Conclusions. The developed test system for determining of the AB-VZV concentration in human serum/plasma in terms of its functional characteristics meets the GOST requirements, is characterized by high diagnostic efficiency, can be used to monitor the effectiveness of vaccine prophylaxis and strength of population immunity, as well as to assess the immune response in chickenpox and Herpes zoster.

On the Road to Individualization of Vaccination: the Significance of Age and Sex

Relevance. The high variability of protection against vaccine-controlled infections, including COVID-19, is one of the actual problem of infectology. Aim. Based on the results of scientific publications and reports, the role of age and sex factors, their interactions and the main mechanisms in the immune response to vaccines, in the improvement of vaccines and vaccination regimens, has been analyzed. Conclusion. It has been shown that vaccine prophylaxis has always developed in the direction of individualization, going through the stages of defining target groups and developing immunization schemes for various groups. The important data obtained in recent decades on the importance of genetic and external factors, in particular, age and sex, in the variability of response to vaccines are analyzed. Analysis of the role of such factors has also been performed for coronavirus vaccines. The necessity and possibilities of next steps that can provide optimal responses of different people to vaccination were discussed.

Tick-Born Relapsing Fever and Genespecies Diversity of Borrelia: Current Status

Relevance. Tick-borne relapsing fevers caused by Borrelia species pathogenic for humans are not well understood. Aim of this review is to assess the genetic diversity of Borrelia with special attention to the relapsing fever group and phylogenetically related species carried by ticks. The review also provides up-to-date information on the main vectors and their geographic distribution, reservoirs of borrelia – pathogens, and potential pathogens of tick-borne recurrent fevers. Conclusions. New types of Borrelia, including a candidate, of relapsing fever clade and related phylogenetic lines/groups, which are carried not only by argasid, but also by solid-body ixodids ticks, deserve further study. The preservation of the epidemic potential of tick-borne relapsing fever can be facilitated by climatic changes, and poorly studied adaptation mechanisms of Borrelia to the range of vectors.

World Experience in the Use Serogroup B Meningococcal Vaccines (literature review)

Relevance. The success of vaccine prophylaxis of meningococcal infection depends on the composition and properties of vaccine preparations and the strict implementation of recommendations on vaccine prophylaxis tactics by the territorial epidemiological characteristics of meningococcal infection. Despite the high burden of B-meningococcal infection, especially among young children, the design of B-meningococcal vaccines has faced serious difficulties. Aim. The literature review presents the history of the development of B-meningococcal vaccines and provides characteristics of two immunologically effective and safe new generation B-meningococcal vaccine preparations. Conclusion. The licensing of the two new B-meningococcal vaccines presented in the review (Bexsero and Trumenba) was based on immunogenicity and safety. The inclusion of vaccines in national vaccination programs requires careful analysis, including analysis of the antigenic characteristics of circulating strains.

The Cases of COVID-19 and Measles Co-Infection in Children

Relevance. The rapid spread of new pathogens inevitably leads to the occurrence of joint circulation with already known infectious agents, leading to the development of mixed infections. The simultaneous circulation of the pandemic coronavirus SARS-CoV-2 with a highly contagious measles virus leads to the development of mixed infections in people who have not been sick or vaccinated against measles. Aims. Review cases of co-infection with measles and COVID-19 in Moscow. Material and methods. A retrospective study of cases of measles and COVID-19 co-infection in three children with a description of the epidemiological and clinical picture of the disease. Results. In all observed children, the manifestation of the disease was typical for measles, the diagnosis of COVID-19 was established based on a laboratory study carried out in a hospital, which gave reason to count. That the infection with SARSCoV-2 occurred after the infection of children with measles. Conclusions. Different incubation periods can lead to several options for the development of co-infection. The similarity of clinical symptoms at the onset of the disease does not allow excluding a certain infection clinically, without laboratory verification.

Immunobiological Properties of Antigenic Preparations Streptococcus pneumoniae and their Mixtures

Relevance. Type-specific immunity does not protect against infection with other pneumococcal serotypes. The phenomenon of the change of serotypes dominating the population of Streptococcus pneumoniae is known, in part due to the intensive recombination process and the phenomenon of «capsule switching». Therefore, the development of a serotype-independent pneumococcal vaccine is an important global public health priority. Ams. Investigation of immunobiological properties of candidate components of a future vaccine with serotype-independent activity. Materials and methods. For immunization of mice, preparations of the capsular polysaccharide of pneumococcus serotype 3 (CPS) were used; protein-containing fraction (PCF) obtained from an aqueous extract of S. pneumoniae 6B cells; recombinant pneumolysin (Ply); mixtures of drugs (CPS + Plу; CPS + PCF; PCF + Plу); conjugate vaccine Prevnar 13 (manufactured by PFIZER Inc. USA). Mice were immunized intraperitoneally, 2 times with an interval of 14 days. Intact mice were used as a control group. To assess the humoral immune IgG response, the method of solid-phase ELISA was used. Phagocytic activity was studied at 7, 14, 21 and 28 days after the second immunization. The cytokine level was determined in the blood sera of mice after the second immunization 2, 4, 8, and 24 hours later on a NovoCyte flow cytometer (ACEA Biosciences, USA) using the MACSPIex CytoKine 10 Kit mouse (Miltenyi Biotec Inc., USA) according to the manufacturer's instructions. Results. Immunization of mice with Ply as well as mixtures with CPS and PCF caused a significant increase in the level of antibodies to Ply. It was found that there was no apparent decrease in the level of antigen-specific antibodies when antigens were administered in combination with others. Pneumolysin, used alone or in combination with PCF and CPS, induces the production of antiinflammatory cytokines IL-4, IL-10, and IL-5 detected throughout the study. This is confirmed by a study of the opsonophagocytic activity of neutrophils from immunized CPS + Ply, Ply + PCF and Ply mice; a significant increase in the number of eosinophils is observed in their blood due to the stimulation of their production of IL-5. Conclusions. As a result of the studies, it was shown that Ply, used alone or in combination with CPS and PCF, has the highest immunogenicity: it stimulates a significant increase in the level of specific antibodies, stimulates Th-2, and induces the production of anti-inflammatory cytokines.

Epidemiological Community and Differences of Transmissive Infections in Astrakhan Region

Relevance. The territory of the Astrakhan region hosts natural foci of severe infections of arbovirus etiology – Crimean-Congo hemorrhagic fever (CCHF) and Astrakhan fever (spotted fever resembling the Mediterranean spotted fever, Astrakhan spotted fever (ASF). The long-term average incidence of CCHF and ASF in the Astrakhan region is to 11 and 135 times higher, respectively, than the average incidence in the Russian Federation. Aims. To present, based on epidemiological data, a comparative characterization of transmissible infections of CCHF and ASF in the Astrakhan region. Materials & Methods. The main method of the study was epidemiological. The data for 2000−2016 of primary medical documentation Ф.058/у «Emergency notification of infectious disease, food, acute occupational poisoning, unusual reaction to vaccination», federal statistical observation Ф. 2 «Information on infectious and parasitic diseases», Ф. 357/у «Epidemiological examination card of infectious disease focus», Ф. .003/у «Medical card of inpatient patient», presented by Center of hygiene and epidemiology in Astrakhan region. For retrospective epidemiological analysis, we studied the absolute and intensive morbidity indicators (per 100 ths population), by age, professional groups, and among the urban and rural population. Based on the average long-term morbidity indicators of the population, a mapping of the territory of the Astrakhan region was carried out. The influence of natural and climatic conditions on the epidemic process of CCHF and ASF was assessed by meteorological data (amount of precipitation, air temperature, etc.). Materials of long-term observation over 11 districts of Astrakhan region and Astrakhan city were analyzed, including data on the spread of Ixodid ticks, population contact with them (according to the attendance of people to treatment-and-prophylactic organizations of the region). Statistical data processing was carried out using the method of straight-line alignment of dynamic series of morbidity indicators, calculation of the average annual rate of decrease/increase. Correlation analysis was used to assess the direction and strength of the relationship between the indicators, and quantitative dependence between epidemic process characteristics. Differences between the indicators were considered to be reliable if p < 0.05. Results. During the analyzed period 151 cases of CCHF and 3951 cases of ASF were identified. By 2016. CCHF was registered in all 11 districts of the region and the area of foci covered 44,000 km2 and 44,100 km2, respectively. There are no differences significantly affecting the epidemic process of CCHF and ASF, so preventive measures are mainly aimed at controlling the vectors of the pathogens of these infections. The comprehensive study of the territory of Astrakhan region carried out in 2000–2016 revealed expansion of CCHF and ASF areal of disease (by 11.8% and 23.4% respectively) and determined the territories with the highest risk of infection, which allowed to increase and redistribute the volumes of acaricide treatments of the territories with the highest infection risk and ensure the decrease of CCHF and ASF morbidity rates. Conclusion. As a result of the comprehensive study conducted in 2000–2016 in the territory of Astrakhan region, the expansion of CCHF and ASF areal of disease was revealed (by 11.8% and 23.4% respectively) and the areas of highest infection risk were identified, which allowed to increase and redistribute the volume of acaricide treatments of the areas of highest infection risk and ensure the reduction of CCHF and ASF morbidity.

Preventive Efficacy of Pneumococcal Conjugated Vaccine (Population Aspects)

Relevance. Pneumococcal disease remains an urgent public health problem, despite mass immunization of infants and young children. The impact of children’s universal vaccination on the morbidity and etiological structure in various clinical forms of infection remains unclear in children and adults. Аim. Тo evaluate the herd effect of children’s mass immunization with a 13-valent conjugated pneumococcal vaccine. Materials and Methods. The prophylactic efficacy of mass vaccination is studied within comparative retrospective epidemiological analysis of incidence rates and etiological structure of bacterial meningitis, ear diseases and mastoiditis, and community-acquired pneumonia in children and adults of Krasnoyarsk region in the pre- and post-vaccination periods, according to the official statistics and microbiological monitoring. Results. The changes in decrease of incidence rates with all clinical forms of pneumococcal infection except community-acquired pneumonia are revealed both in children and adults during mass immunization. Etiological structure changes and also changes of S. pneumoniae serotype distribution are detected in major clinical forms of infection. Conclusion. Reducing the incidence rates in children is determined predominantly by vaccinal prevention. The observed decrease of incidence rates in adults is the result of reducing the number of pneumococcal infection sources among children (herd immunity).

Multi-Level Monitoring of Vaccination Adherence of Various Population Groups in the Context of the COVID-19 Pandemic: Problematic Issues

Relevance. Despite significant progress in the prevention of many infectious diseases, a number of organizational issues remain in the area of special attention. One of them is to ensure the timeliness and completeness of vaccination coverage in the decreed age groups, which is possible only with a high level of public commitment to vaccination. During the pandemic of the new coronavirus infection (COVID-19), achieving a high level of vaccination coverage of the National Calendar of Preventive vaccinations is of particular relevance. Aim. Using state-of-the-art online resources, assess population vaccination adherence to develop effective communication risk management technologies for immunoprophylaxis in the COVID-19 pandemic. Materials and methods. To assess the commitment of various population groups and professional contingents of a large industrial city to vaccine prevention, a survey of 965 parents was conducted at the initial stage, and subsequently a survey of 2,632 employees of medical organizations, including 1,422 people in the period before the COVID - 19 pandemic, 572 people in the «first wave» of the pandemic and 638 people in the «second wave». Instagram Facebook, Instagram, and VKontakte social networks were used to quickly obtain the necessary information (Google forms, corporate e-mails, WhatsApp, Telegram messengers, etc.). The work uses epidemiological, sociological and statistical methods of research. Results and discussion. When assessing the attitude of parents to vaccination, it was found that 78.8% of respondents were positive about vaccinations, 14.6% doubted their effectiveness and safety, and 6.6% denied their need. The main source of information that forms the attitude to vaccinations of parents was the opinion of medical professionals. In a survey of 1,422 employees, 190 people (13.3%) were identified, mainly from among the trained specialists, who themselves had a negative attitude to vaccination. When assessing the commitment of employees of medical organizations to the vaccination of a new coronavirus infection, the attitude to vaccination was ambiguous, especially in the group of secondary medical personnel and female employees of non-medical specialties, who are a potential risk group for forming a negative attitude to vaccinations and can act as «opinion leaders» on this issue for other categories of the population. Insufficient adherence to COVID-19 vaccine prevention has also been observed in other countries among various population groups, which is a serious problem on a global scale, hindering the fight against the pandemic of a new disease, which requires corrective measures. Conclusion. In this study, using modern online resources, a rapid assessment of the vaccination adherence of various population groups (parents and medical professionals) was carried out. It is shown that the use of modern technologies and software tools makes it possible to analyze a large array of data to solve problems of overcoming communication risks. The results obtained point to the need for prompt corrective measures in terms of the introduction of educational programs to increase adherence to vaccination, especially in groups at potential risk of the disease, including medical professionals, which is a priority for health care in all countries.

Enhancement of the Yersinia pestis EV NIIEG Vaccine Srain Immunogenic and Protective Activity under Cultivation with Azoxymer Bromide (Polyoxidonium)

Background. The live-attenuated vaccine based on the Yersinia pestis strain EV line NIIEG is still used in Russia, providing protective efficacy against plague. Nevertheless, there is an urgent need for developing new ways to increase the immunogenicity of the Y. pestis EV NIIEG vaccine strain. In this study, the ability of direct action of immunoadjuvant azoximer bromide (polyoxidonium, PO) on the immunobiological properties of vaccine strain Y. pestis EV NIIEG during cultivation on a dense nutrient medium was evaluated. Materials & Methods. Y.pestis EV NIIEG, cultivated at 28 °С for 48 h on LB agar, Miller pH 7.2 ± 0.1 (Sigma-Aldrich, USA) with the addition of PO and without. MALDI-TOF mass-spectrometry was deployed for the obtainment of mass-spectra of ribosomal proteins from Y. pestis EV NIIEG cells on the MicroflexTM LT mass spectrometer (Bruker Daltonics, Germany). Protective efficacy was evaluated under subcutaneously challenge guinea pigs and mice BALB's with 400 LD50 doses of the Y. pestis 231, Y. pestis P-13268 Vietnam (MLD=5 CFU). Antibody titers to F1 in serum were determined using an ELISA. Results. The addition of the therapeutic concentration of PO in the cultivation medium induced a significant increase in the immunogenicity of Y. pestis EV NIIEG that resulted in enhancement of serum antibody levels against Y. pestis F1 antigen and several times the growth of protective efficacy in the bubonic plague model on two types of experimental animals. ImD50 of the vaccine strain Y. pestis EV NIIEG, cultivated with PO, was significantly (p < 0,05) lower in comparison to ImD50 for Y. pestis EV NIIEG in standard cultivation conditions. One year of storage at a temperature of 4 °С did not alter the protective properties of the vaccine strain Y. pestis EV NIIEG, cultivated with PO. Conclusions. Morphological studies confirmed the absence of influence PO introduction into the cultivation environment on the safety of the vaccine strain. MALDI-TOF MS profile of the Y. pestis EV NIIEG, cultivated with PO, had peaks characteristic features. The mass peak at m/z 3,061 was significantly down-regulated and new mass peaks at m/z 2,759, m/z 3,533 were determined. These changes are accompanied by the increase of Y. pestis EV NIIEG immunogenicity.