The Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction places CN-containing toxic chemicals like tabun and its numerous homologues and analogues (around 10.000 organic compounds), hydrogen cyanide, cyanogen chloride etc., under the international control in the field of arms control, disarmament and non-proliferation. Moreover, CN-containing toxic chemicals are hazardous industrial and environmental pollutants. Soils are the most widely-spread and complex environmental objects for the detection and analysis of cyanides. The aim of this work is to elaborate the method for measuring mass concentration of cyanides in soil samples, which is more sensitive and less labor-intensive, than photometric method, adopted in the Russian Federation. The developed method involves the use of 2,3,4,5,6-pentafluorobenzyl bromide as a derivatizing agent and GC/MS/MS with methane negative ion chemical ionization. It enables the identification and quantification of cyanide ions in soil in the range of 0.7 ng/g – 10.0 μg/g. This method is much more sensitive than the photometric method, included in the federal registry. It does not require the use of potassium cyanide isotopes with radioactive labels of carbon and potassium as an internal standard, and it requires less implementation time.

The genetic diversity of coronaviruses and their variability are provided by high frequency of recombination of their genomic RNA that assists spontaneous emergence of viruses with new characteristics, which potentially may be agents of novel extremely dangerous and exotic infectious diseases. In December 2019 – January 2020 the novel coronavirus disease, caused by SARS-CoV-2 virus, subsequently named COVID-19 (Corona Virus Disease 2019), was revealed in China. The aim of this work is to analyze the possible mechanism of COVID-19 outbreak and the properties of the possible etiological agent of the disease, SARS-CoV-2 virus. A comparison of zoonotic reservoirs of highly pathogenic human coronaviruses, agents of severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and SARS-CoV-2, as well as the clinical signs of the diseases, caused by them, are presented. The possible mechanism of epidemic outbreaks is considered. The chronology of COVID-19 outbreak (later escalated into a pandemic) from the beginning of December to the end of March, taxonomical and molecular-biological characteristics of ethiological agent of disease, SARS-CoV-2 virus, and its place on phylogenetic tree of coronaviruses are presented. The main directions of the struggle with the spread of the infection are considered.

The seemingly unexpected appearance of SARS-CoV-2 in China and its subsequent rapid spread throughout the world make us think seriously about the coronavirus threat emanating from natural foci in the territory of our country. The aim of this work is to study SARS-CoV-2 in the context of real global epidemiology of coronavirus infections. The data of Chinese scientists, published in Englishlanguage scientific journals, has been used during the preparation of the article. Their analysis showed the vast spread of viruses of this taxon among bats and hedgehogs in the natural ecosystems of Europe as well. To date the host of SARS-CoV-2 virus, intermediate between bats and humans, as well as the intermediate coronavirus, the direct predecessor of SARS-CoV-2, have not been detected. The bulk of the coronavirus genome is conservative, but it appears to be extremely prone to genetic recombination in vivo, so the virus can be redirected both in natural and artificial conditions from wild animals to humans by changing the structure of the S1 protein. The pathogenesis of coronavirus infections in humans that causes severe acute respiratory syndrome (SARS), include the specific recognition of receptors on target cells in the lower parts of human lungs, the penetration of the virus into the target cells, viral replication, generation of cytokine responses, that destroy the lower parts of the lungs, and the appearance of the phenomenon of antibody-dependent enhancement of the infection, that results in generalized spread of the virus. The virulence of SARS-CoV-2 for humans is significantly lower than that of the coronaviruses that caused SARS in 2002–2003 in China and the Middle East respiratory syndrome in the Middle East in 2012. However, due to the higher stability of the virus when penetrating the endosomes of the cell and the effectiveness of the replication/transcription complex, the virus replicates to large enough numbers to transmit easily from ill people to healthy. Different ethnic groups have different sensitivity to SARS-CoV-2 because of the different amounts of ACE2 receptors on the surface of type II pneumocytes. The article also sketches certain clinical observations made by Chinese researchers during an outbreak of coronavirus infection caused by SARS-CoV-2. The author states, that effective and timely diagnosis of COVID-19 is possible only by the combination of molecular diagnostics of SARS-CoV-2 and the detection of characteristic pneumonic foci by computed tomography.

There are several possible reasons for the return of smallpox as an endemic disease. For example, the possibility of maintaining smallpox virus in an active state in the corpses of the dead, buried in permafrost regions, or the evolutionary changes of orthopoxviruses with the appearance of more virulent strains. Since the eradication of smallpox, the requirements for smallpox vaccines have changed, leading to a change in the principles of smallpox vaccination. The purpose of the study is to review the evolution of means and principles of smallpox vaccination. For almost 200 years four generations of vaccine preparations have been developed. The first ones were the dermovaccines, i.e. the virus-containing detritus of calfskin. Then, chicken-embryo-skin cell cultures were used as a substrate for virus accumulation. The third generation were the vaccines based on vaccine strains at-tenuated by various methods. Fourth, DNA vaccines and subunit recombinant vaccines. One of the main contemporary principles of smallpox vaccination is safety (limited use of the vaccines of first and second generations, the development of next generations of vaccines, means and schemes of safe vaccination) while maintaining the requirements of efficiency equal to the existing vaccines. The replacement of epidemiologically tested vaccines with the third and fourth- generation drugs necessitated a comparative assessment of the protective efficacy and safety of new vaccines. It may be useful to carry out two-stage vaccination using inactivated or new safe nonreplicating the third and fourth generation vaccines at the first stage.