Problems of Virology

The basis for criteria of the taxonomic classification of DNA and RNA viruses based on data of the genomic sequencing are viewed in this review. The genomic sequences of viruses, which have genome represented by double-stranded DNA (orthopoxviruses as example), positive-sense single-stranded RNA (alphaviruses and flaviviruses as example), non-segmented negative-sense single-stranded RNA (filoviruses as example), segmented negative-sense single-stranded RNA (arenaviruses and phleboviruses as example) are analyzed. The levels of genetic variability that determine the assignment of compared viruses to taxa of various orders are established for each group of viruses.

Introduction. Specific prevention of a number of infectious diseases has been introduced into the vaccination schedule. The production of immunoprophylactic drugs, in order to establish standard properties, including safety and specific effectiveness, requires strict adherence to manufacturing regulations, and the reliability of the results obtained requires monitoring of these parameters. The specific effectiveness of vaccine preparations is standardized according to the indicators of stimulation of specific antibody response formed in the body of vaccinated model biological objects.

Objective. Determination of the immune reactivity of white mice to vaccination with the QazVac vaccine to establish the possibility of using them as a biological model in assessing the immunogenicity of the vaccine instead of Syrian hamsters.

Materials and methods. The immune reactivity of model animals was assessed by the seroconversion rate, dynamics of antibody titers to the SARS-CoV-2 virus formed in the body after vaccination with the test vaccine. In the case of seropositivity of animals before administration of vaccine or placebo, the level of immune reactivity was calculated by the difference in antibody titers between control and vaccinated animals or by the difference in antibody titers before and after immunization. Specific antibodies were detected and their titer was determined using a neutralization reaction.

Results. The research results showed that the tested biological models had approximately the same immune reactivity to the administration of the QazVac vaccine, confirmed by the level and dynamics of antibody titers. When analyzing the fold increase in antibody titers in comparison to those of control animals, Syrian hamsters were more reactive compared to mice. But SPF white mice were standardized in their lack of the immune reactivity to SARS-CoV-2 virus before the immunization.

Conclusion. The data obtained indicate that the immune reactivity of white mice to the administration of the QazVac vaccine in terms of the rate and dynamics of the formation of virus-neutralizing antibodies is approximately equivalent to the immune reactivity of Syrian hamsters. Before immunization with the vaccine, SPF white mice, in contrast to Syrian hamsters, do not have humoral immunity specific to the SARS-CoV-2 virus. The immune reactivity equivalent to that observed of Syrian hamsters and the absence of antibodies to the SARS-CoV-2 virus at a baseline indicate the superiority of the use of white mice in assessing the immunogenicity of vaccines against COVID-19 and/or obtaining specific factors of humoral immunity.

Introduction. The rapid spread of African swine fever in the Kaliningrad region makes it necessary to use the methods of molecular epidemiology to determine the dynamics and direction of ASF spread in this region of Russia.

The aim of the study was to determine single nucleotide polymorphisms within molecular markers K145R, O174L and MGF 505-5R of ASFVs isolated in Kaliningrad region and to study the circulating of the pathogen in European countries by subgenotyping and spatio-temporal clustering analysis.

Materials and methods. Blood samples from living domestic pigs and organs from dead domestic pigs and wild boars, collected in the Kaliningrad region between 2017 and 2022 were used. Virus isolation was carried out in porcine bone-marrow primary cell culture. Amplicons of genome markers were amplified by PCR with electrophoretic detection and subsequent extraction of fragments from agarose gel. Sequencing was performed using the Sanger method.

Results. The circulation of two genetic clusters of ASFV isolates on the territory of the Kaliningrad has been established: epidemic (K145R-III, MGF 505-5R-II, O174L-I – 94.3% of the studied isolates) and sporadic (K145R-II, MGF 505-5R-II, O174L-I – 5.7%).

Conclusion. The broaden molecular genetic surveillance of ASFV isolates based on sequencing of genome markers is necessary in the countries of the Eurasian continent to perform a more detailed analysis of ASF spread between countries and within regions.

Introduction. COVID-19 is strongly linked to cardiovascular disease, with direct myocardial injury and systemic inflammation as common mechanisms. Pre-existing or infection-induced cardiovascular disease worsens the outcomes for COVID-19 patients.

Materials and methods. To estimate the serum electrolytes (Na⁺, K⁺, Ca⁺⁺, Zn) and vitamin D₃, the study depended on ichroma ii device for Vitamin D₃ and Chemistry Analyzer for electrolytes in patient samples.

Results. A study was conducted on 192 individuals diagnosed with COVID-19, including 35 critical cases, 53 severe cases, 54 moderate cases, and 50 individuals in a control group. The age group with the highest prevalence of infection was between 50‒69 years, while the lowest prevalence was observed in those under 30 years. The study found significant decreases in calcium, potassium, sodium, zinc, and vitamin D₃ levels among COVID-19 patients compared to the control group. Zinc and vitamin D₃ levels showed a significant correlation with sex, with males experiencing a decline in zinc levels and females having lower vitamin D₃ levels. The concentration of calcium, sodium, and zinc showed a negative correlation with age, with older patients having the lowest levels. COVID-19 patients with chronic cardiac issues and high blood pressure exhibited the lowest levels of these markers. The severity of the disease also had a detrimental impact on electrolyte levels, zinc, and vitamin D₃, with critical cases showing the lowest levels. The complications such as heart failure were associated with lower levels of potassium, sodium, and zinc.

Conclusion. In conclusion, the study revealed significant associations between COVID-19 and decreased electrolyte levels, zinc, and vitamin D₃. Sex and age were found to be correlated with these markers. Patients with chronic cardiac issues and high blood pressure exhibited the lowest levels of these markers. The severity of the disease was also linked to lower electrolyte levels, zinc, and vitamin D₃. Complications such as heart failure were associated with decreased levels of potassium, sodium, and zinc.

Introduction. Hemorrhagic fever with renal syndrome (HFRS) is the most common zoonotic human viral disease in the Russian Federation. More than 98% of the HFRS cases are caused by Puumala orthohantavirus (PUU). Effective serological tests are required for laboratory diagnosis of HFRS.

Objective. Construction of an enzyme immunoassay (ELISA) test system for detection of specific antibodies using standard antigen in the form of highly purified inactivated PUU virus as immunosorbent.

Materials and methods. Preparation of PUU virus antigen, designing the ELISA for detection of specific antibodies, developing parameters of the ELISA system, parallel titration of HFRS patients sera by fluorescent antibody technique (FAT) and the new ELISA.

Results and discussion. For the first time, ELISA based on purified inactivated PUU virus as standard antigen directly absorbed onto immunoplate was developed. Parallel titration of 50 samples from HFRS patients blood sera using FAT and the developed ELISA showed high sensitivity and specificity of this ELISA, with 100% concordance of testing results and significant level of correlation between the titers of specific antibodies in the two assays.

Conclusion. The ELISA based on purified inactivated PUU virus as an immunosorbent can be effectively used for HFRS serological diagnosis and for mass seroepidemiological studies.