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The widespread use of the oral poliovaccine from Sabin strains (tOPV) radically reduced poliomyelitis incidence worldwide. However, OPV became a source of neurovirulent vaccine-derived polioviruses (VDPVs). Currently, circulating type 2 VDPVs (cVDPV2) are the leading cause of poliomyelitis. The novel OPV type 2 vaccine (nOPV2), based on genetically modified Sabin strain with increased genetic stability and reduced risk of cVDPV formation, has been used to combat cVDPV2 outbreaks, including one in Tajikistan in 2021. In order to identify the importation of cVDPV2 and nOPV2-derivates, stool samples from 12,127 healthy migrant children under 5 years of age arriving from Tajikistan were examined in Russia (March 2021-April 2022). Viruses were isolated in cell culture and identified via intratype differentiation RT-PCR, VP1 and whole-genome sequencing. cVDPV2 isolates closely related with the Tajikistan one were isolated from two children, and nOPV2-derived viruses were detected in specimens from 106 children from 37 regions of Russia. The duration of nOPV2 excretion ranged from 24 to 124 days post-vaccination. nOPV2 isolates contained 27 mutations per genome (0.36%) on average, with no critical genetic changes, which confirms the genetic stability of nOPV2 during field use. The possibility of epidemiologically significant poliovirus introduction into polio-free countries has been confirmed. The screening of special populations, including migrants, is required to maintain epidemiological well-being.

The first application results of enzyme immunoassay system (ELISA) - binding inhibition ELISA (BI ELISA) for the detection of antibodies to polioviruses of three types based on the use of specific antibodies from chicken yolk (IgY) are presented. This variant of ELISA is a "surrogate" neutralization test (NT). When comparing the results of the detection of antibodies in 90 sera of children who were vaccinated with oral and inactivated poliovirus vaccines, good correlation (r = 0.67, 0.61, 0.76 for types 1, 2, 3 respectively) between the BI ELISA and the NT results was shown. The presented variant of ELISA is the further stage of the development of "IgY-technology" for laboratory diagnostics of viral infections, namely poliovirus infection, which can be used for seroepidemiological studies as an analogue of the NT which requires the use of life poliovirus with the required standard of biosafety containment facilities., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The goal of this work was to estimate the collective immunity against poliomyelitis among the population of 8 regions and republics of Russia. The rates of the collective immunity against poliomyelitis allow the polio vaccination quality to be estimated and the population protection rate to be simultaneously demonstrated. A total of 8 regions (2138 people) were tested. The antibodies to the polioviruses of 1-3 types were determined against the vaccine Sabin strains in the neutralization test in the RD cell line. As a result, we found that vaccination against poliomyelitis in all observed regions was maintained at the required high level. Thus, the number of people with antibodies to the polio in most regions and age groups approximates or reaches 100%, while GMT is also high. This work demonstrated the necessity of the continuation of vaccination against poliomyelitis and control over collective immunity.

Aim: Study the state of collective immunity against poliomyelitis in 7 regions of Russia in the last 3 years., Materials and Methods: 2579 sera were studied for antibodies against poliomyelitis virus. Antibodies (AT) against 3 types of viruses were determined in neutralization reaction in RD cell culture, the state of collective immunity in the examined individuals was evaluated by the percent of individuals with AT against a type of poliovirus and geometric mean AT titer. The circulation of wild polioviruses was judged by the presence of strain specific AT against wild and vaccine viruses in the examined children (311 sera were studied)., Results: The indicators of collective immunity against poliomyelitis in both select examined regions and select age groups were generally high. The data obtained allow to make a conclusion that the quality of vaccine prophylaxis in the examined regions is good. Introduction of wild poliovirus type 1 from Tajikistan in 2010 caused disease in 7 residents of Russia whereas an epidemic that had affected more than 700 individuals emerged in Tajikistan., Conclusion: The studies carried out confirmed the necessity to continue qualitative poliomyelitis vaccine prophylaxis in the country despite the lack of circulation of wild polioviruses that can be introduced at any time.

Problem of poliomyelitis eradication is examined in the review. After the eradication of wild poliovirus, vaccine poliomyelitis virus continues to circulate in the human population. In rare cases it can cause the development of the disease. The authors describe disadvantages of the use of oral and inactivated poliomyelitis vaccines and note that by using oral poliomyelitis vaccine and eradication only of wild poliovirus, eradication of poliomyelitis as an infection will not succeed. As one of the approaches to reach this goal the authors propose the use of various enterovirus interference. Use of live enterovirus vaccine is described and its advantages and disadvantages are examined.

Coxsackie A viruses belong to the enteroviruses, the isolation of which from infectious materials and further cultivation are possible only when laboratory animals are infected. The authors could adapt the strains of 17 of 23 serotypes of these viruses to RD cell culture. The strains of 8 serotypes were additionally adapted to Vero cell culture. The cultural variants of Coxsackle A viruses were used to prepare immune sera. The Bacterial and Viral Agents Enterprise, M. P. Chumakov Institute of Poliomyelitis and Virus Encephalitides, Russian Academy of Medical Sciences, has set up the production of bacterial and viral drugs based on the cultural variants of 5 Coxsackie A virus serotypes. The cultural variants of 14 Coxsackie A virus serotypes were used to carry out a virus neutralization test. Examination of more than 600 children from Moscow and the Moscow Region showed the wide circulation of individual Coxsackie A virus serotypes. It also demonstrated a drastic reduction in Coxsackie A-7 virus circulation in the past 50 years.

The WHO global polio eradication initiative launched in 1988, by eradicating wild polio viruses, was to be completed in 2000. The initiative had not been implemented. Enormous work has resulted in a reduction in the number of poliomyelitis cases worldwide from 350,000 to 1,500-2,000 a year. However, the incidence of poliomyelitis does not and is unlikely to stop by the newly fix date--2013. The reason is that vaccine-derived polio viruses that are pathogenic in nature remain and long circulate in the earth. The circulation in human beings leads to the restoration of their neurovirulence and ability to induce severe paralytic diseases. In 1999 the WHO reported the global eradication of wild polio virus type 2 and therefore there should not be diseases caused by polio virus of this type. Nevertheless, the virus-induced diseases continue to emerge. About 300 cases of diseases induced by vaccine-derived poliovirus type 2 had been notified by July 2009. At present, there is no way to eradicate all polio viruses worldwide so the case in point may be only to stop their transmission or minimize morbidity with on-going vaccination.

Herd immunity against poliomyelitis was studied in 1391 children and adolescents from 10 towns of the Moscow Region. It was ascertained that the values of herd immunity against poliomyelitis virus type 1 were high everywhere and those of herd immunity against poliomyelitis virus type 2 were high and very high in 9 towns and below the WHO minimum levels (80%). The values of herd immunity against poliomyelitis virus type 3; they were lower than the required minimum in 2 towns and very low in 2 other towns arouse alarm. The study of strain-specific antibodies to vaccine-derived and wild polioviruses has demonstrated that wild poliomyelitis viruses have not circulated in the areas of the examinees in the past decade.

Assessment of immunity to poliomyelitis in adults from 8 towns of Moscow region was conducted. Low levels of population immunity against some serotypes of poliovirus in several towns have been found. At the same time, these levels were high and very high in other towns. Measurement of levels of strain-specific antibodies to vaccine and wild polioviruses demonstrated wide circulation of wild polioviruses during past decades which had significant influence on formation of immunity. Substantial number of non-immune adults represents favorable conditions for circulation of vaccine polioviruses after cessation of vaccination, which, in its turn, could result in reestablishment of their neurovirulent properties and subsequent reemergence of poliomyelitis.

Collective poliomyelitis immunity was studied in 6339 donors from 19 towns and cities of Russia. Its stress substantially varied in different towns and cities. Studies of strain-specific antibodies to vaccine and wild viruses of poliomyelitis in donors from 4 towns established that the immune persons were more in the town where wild polioviruses had previously circulated than in those where the circulation of wild polioviruses had been limited and immunity resulted from vaccination. Circulation of vaccine viruses and reversion of their neurovirulent properties should be expected in the town where there are low collective poliomyelitis immunity rates. It is concluded that it is impossible to eradicate poliomyelitis as infection today; it is possible only to eliminate the disease if further vaccination of children is performed with live poliomyelitis vaccine.

The modern view of the role of enteroviruses in the eradication of poliomyelitis is presented. Enteroviruses were discovered in the XX century. In the 1950s they caused great epidemics of poliomyelitis and serous meningitis in many countries of the world. The introduction of oral poliomyelitis vaccine (OPV) into medical practice made it possible to eliminate the epidemics of poliomyelitis in a short time. Poliomyelitis morbidity was reduced to sporadic cases and in a number of regions disappeared. OPV produced non-specific influence also on the epidemics of serous meningitis, as well as on a case incidence. The eradication of poliomyelitis viruses and the cessation of immunization with OPV will not result in eradication of paralytic diseases. Paralytogenic viruses of 20 serotypes circulate in nature, and some of these viruses are capable of causing the outbreaks of severe paralytic diseases. The authors propose either to retain immunization with OVP as tour immunizations with monovaccine of type 2, or to create new live enterovirus vaccines on the basis of avirulent enterovirus strains.

Essential differences in the intensity of collective immunity to poliomyelitis in the donors of Moscow and Kaluga were established. To find out the nature of high characteristics of collective immunity to poliovirus, types 1 and 2, in the donors of Kaluga, strain-specific antibodies to wild and vaccine polioviruses were studied. In a considerable number of donors strain-specific antibodies to poliovirus, types 1 and 2, were detected. This made it possible to presume a sufficiently wide circulation of these viruses among the population of the city in the middle of the 20th century and, as a consequence, high level of collective immunity appeared. Strain-specific antibodies to poliovirus of type 3 were rarely detected. This made it possible to suggest that the circulation of viruses of this type among the population was limited. Immunity to viruses of this type was due only to immunization. For this reason the characteristics of collective immunity in the donors of Moscow and Kaluga coincided. The detection of strain-specific antibodies to poliomyelitis virus allowed to retrospectively form the opinion of the spread and time of the circulation of wild poliomyelitis viruses in the population.

Immunity induced by immunization with oral poliomyelitis vaccine has long been considered to last for life, similarly to immunity developing after infection with wild poliomyelitis virus. Vaccine virus cannot circulate among the immune population for a long time. The vaccination of children against poliomyelitis, carried out in the course of many years, has made it possible to suggest that a considerable number of immune persons were present among the adult population. The examination of 1,030 Moscow donors has revealed that antibodies to poliomyelitis virus of types 1, 2 and 3 were detected in 47.3%, 45.5% and 76.4% of the examinees respectively, the values of the average geometric titers being low. It is known that passages of poliomyelitis vaccine virus through nonimmune persons may result in emergence of revertant viruses with increased neurovirulence. The nonimmune adult population, especially the mothers of vaccinated and revaccinated children, may serve as favorable environment for the circulation of vaccine viruses and the appearance of revertant viruses.

In response to vaccination or infection with wild poliovirus, some children can finely differentiate the virus structure and respond by forming strain-specific antibodies. The analysis of strain-specific antibodies indicates that in epidemically unfavorable regions strain-specific antibodies to wild poliovirus strains may prevail over those to vaccine poliovirus strains in children or occur with equal frequency. In epidemically favourable regions strain-specific antibodies to vaccine poliovirus strain significantly prevail in children or may be absent at all. The analysis of strain-specific antibodies makes it possible to retrospectively judge on the circulation of wild viruses in the surveyed region.

During the epidemic season of 1989-1990 the subunit vaccine Grippovac was used in 20 asylums for old people and psychoneurological invalids in Moscow for the protection of the inhabitants and the personnel from influenza. Follow-up of the vaccinees during the period from November 1989 to March 1990 revealed that the use of this vaccine decreased the incidence of influenza-like diseases (ILD) 3.4-4.1 times among the vaccinees in comparison with that in the nonvaccinated control groups and significantly decreased the severity of the course of ILD, as well as the mortality because of ILD, among those vaccinees who had contacted ILD. This is indicative of good prospects of regular vaccinal prophylaxis of influenza at asylums for old people and other persons at a high risk of influenza complications.

In the process of the immunological approbation of several experimental batches of the triyalent subunit influenza vaccine Grippovac, the pronounced immunogenicity of the antigens of all strains contained in the vaccine was established; most of the vaccinees were found to retain sufficiently high antibody titers for a year, and the essential total increase of antibody titers was found to occur after a single booster immunization. The serological checking of the diagnosed cases of influenza among immunized and nonimmunized children, carried out in two boarding schools during the influenza epidemic in the winter of 1984-1985 provided the proofs of the high effectiveness of Grippovac in preventing viral influenza, types A and B: the decrease of influenza morbidity among the immunized children reached 79,5-67,2-66,5% and the total morbidity rate in influenza in these two boarding scholls dropped, on the average, 3,0-3,5 times.

During the autumn-winter epidemic of influenza-like diseases in December, 1983--first quarter, 1984, in Moscow commissioned coded observations on the effectiveness of prophylactic vaccination against influenza of 3-7-year-old children with a preparation "Grippovak SE-AZh" were carried out in day-care centers. In the previous large-scale trials, 1981-1984, the "Grippovak" had been evaluated positively as a completely harmless, serologically and immunologically active preparation reducing 3-3.5-fold the number of laboratory-verified cases of viral type A and B influenza in the vaccinees. In 1986, however, the "Journal of Microbiology, Epidemiology, Immunology" (JMEI, 2: 49-54) published a paper whose authors, on behalf of the Commission which had checked the preparation in the day-care centers (Z.A. Bashliaeva, A.A. Sumarokov, et al.), came to a conclusion that "Grippovak" was ineffective in children. Other members of the above Commission disagreeing with this conclusion made a repeat analysis of the decoded materials of the observations in the day-care centers using computer methods and demonstrated that because of significant prevalence of non-influenza ARD cases and recurrent (up to 44%) ARD cases in children in the 4 months of observation, it was impossible to judge the effectiveness of the vaccine by comparison of the total incidence of influenza and ARD from the clinical data alone in the vaccinees and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Twelve poliovirus isolates of serotype 3 from patients with paralytic poliomyelitis have been analyzed by oligonucleotide mapping of the viral genomes. All the studied strains were isolated from patients in different regions of the Moldavian SSR in 1982. The maps of all isolates are similar but they do not practically possess any large oligonucleotides characteristic of the vaccine strain of type 3 poliovirus. It is concluded that a wild neurovirulent strain of type 3 poliovirus, that circulated in 1982 in the Moldavian SSR was the cause of paralytic poliomyelitis cases. All the studied isolates are suggested to have been derived relatively recently from the common ancestor.

Examinations of ARD patients in an orphanage for defective children in Moscow during an influenza outbreak in the winter of 1988 yielded 12 influenza virus strains, including 6 influenza B strains and 6 influenza A (H3N2) strains. The antigenic analysis of hemagglutinin of influenza B virus isolates showed that with respect to the B/Leningrad/179/86 strain (an antigenic analogue of B/Ann Arbor/1/86 strain recommended for inclusion into the influenza vaccine for 1987-1988) they could be divided into 2 groups: antigenically close to the B/Leningrad/86 strain (isolate B/712) and markedly differing from it (the remaining isolates). As compared with reference strains of the previous years, all the new virus isolates fell into 4 groups: isolate B/712 antigenically related to B/Hong Kong/73 and B/Leningrad/86 strains; B/722 antigenically close to B/Singapore/222/79 and B/USSR/100/83 strains; B/724, an antigenic analogue to B/USSR/100/83; and the remaining isolates, to some or other extent, differing from various reference strains. This attests to simultaneous circulation of various antigenic variants of influenza B virus during the 1988 winter outbreak of influenza in Moscow. An interesting feature of the B/712/88 isolate consists in its antigenic specificity of hemagglutinin being indistinguishable from that of B/Hong Kong/8/73 strains.