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Introduction: The well-known advantages of class Y antibodies (IgY) from egg yolks of immunized hens in comparison with class G antibodies (IgG) of laboratory animals traditionally used in laboratory diagnosis of infectious diseases determine the stable interest of researchers in using IgY for these purposes (IgY technology). Over the past 20 years, the obvious benefits of IgY technology have been demonstrated for a number of viral and bacterial infections. Goals and objectives. Construction of ELISA systems based on specific IgY for laboratory diagnosis of infections caused by tick-borne encephalitis virus, yellow fever virus, poliovirus., Material and Methods: Obtaining yolk preparations of immunized chickens, obtaining highly purified IgY preparations (salting out, affinity chromatography), constructing ELISA systems for determining virus-specific antigens, testing the parameters of ELISA systems., Results and Discussion: For the first time in laboratory practice, ELISA systems based on the use of specific polyclonal IgY were designed for laboratory diagnosis of topical human viral infections caused by flaviviruses and enteroviruses: determination of antigens of tick-borne encephalitis virus, yellow fever virus, 3 types of poliovirus. It was experimentally shown that these ELISA systems have high sensitivity and specificity, which allows them to be used for the semiquantitative and quantitative determination of antigens of these viruses in various materials (infected cell cultures, vaccines, etc.)., Conclusion: The ELISA systems developed on the basis of specific IgY for determination of viral antigens can be effectively used for laboratory diagnosis of a number of viral infections, for the validation and control of vaccine preparations., Competing Interests: The authors declare no conflict of interest.

The results of virologic testing of clinical materials and epidemiological analysis of vaccine-associated paralytic poliomyelitis (VAPP) cases obtained in 2006-2013 during AFP surveillance are presented. Among the 2976 cases of AFP 30 cases were VAPP. 15 cases were observed in OPV recipients, whereas 15 cases were observed in non-vaccinated contacts. The age of the patients varied from 4 months to 5.5 years (13.6 ± 12.4 months old). Children younger than 1 year constituted 63.3% of the group; boys were dominant (73.3%); 53.3% of children were vaccinated with OPV; the time period between receipt of OPV and onset of palsy was from 2 to 32 days (18.7 ± 8.2). Lower paraparesis was documented in 48.3% of patients; lower monoparesis in 37.9%; upper monoparesis, in 6.9%; tetraparesis with bulbar syndrome, in 6%. The majority of the patients (85.7%) had an unfavorable premorbid status. The violations of the humoral immunity were found in 73.9% cases: CVID (52.9%), hypogammaglobulinemia (41.2%); selective lgA deflciency (5.9%). In 70.6% cases damage to humoral immunity was combined with poor premorbid status. The most frequently observed (76%, p < 0.05) represented the single type of poliovirus--type 2 (44%) and type 3 (32%). All strains were of the vaccine origin, the divergence from the homotypic Sabin strains fell within the region of the gene encoding VPI protein, which did not exceed 0.5% of nucleotide substitutions except vaccine derived poliovirus type 2--multiple recombinant (type 2/type 3/ type 2/type 1) with the degree of the divergence of 1.44% isolated from 6-month old unvaccinated child (RUS08063034001). The frequency of the VAPP cases was a total of 1 case per 3.4 million doses of distributed OPV in 2006-2013; 2.2 cases per 1 million of newborns were observed. This frequency decreased after the introduction of the sequential scheme of vaccination (IPV, OPV) in 2008-2013 as compared with the period of exclusive use of OPV in 2006-2007: 1 case per 4.9 million doses, 1.4 cases per million newborns and 1 case per 1.9 million doses, 4.9 cases per 1 million newborns, respectively. The study has been financed from Russian Federation budget within the framework of the Program for eradication of poliomyelitis in the Russian Federation, WHO Polio eradication initiative, WHO's European Regional Bureau, Russian Foundation for Basic Research (project No. 15-15-00147).

Aim: Compare frequency of isolation of polioviruses in children living in closed-type facilities (orphanages) before and after the change in poliomyelitis vaccination scheme., Materials and Methods: Feces samples of 207 children from 5 orphanages during immunization with oral poliomyelitis vaccine (OPV) and of 259 children from 4 orphanages during vaccination with inactivated poliomyelitis vaccine (IPV) were studied. Isolation and identification of polioviruses was carried out according to WHO recommendations., Results: In orphanages, where children were immunized with the oral vaccines, 21 polioviruses were isolated. In orphanages, where only inactivated vaccine was used, 10 polioviruses were isolated, the presence of polioviruses in these facilities is associated with their introduction from the outside. The percentage of poliovirus detection in children immunized with OPV was shown to be 16.9 ± 3.4% and was significantly higher than in children vaccinated with IPV (6.1 ± 1.9%). Polioviruses isolated from children immunized with OPV belonged to serotypes 1, 2 and 3 in 19.0, 14.3 and 66.7% of cases, respectively. Polioviruses detected in children immunized with IPV belonged to serotypes 1, 2 and 3 in 30, 40 and 30% of cases, respectively. All the isolated polioviruses turned out to be Sabin vaccine strains., Conclusion: Implementation of strict prophylaxis measures in orphanages is necessary in order to prevent the possibility of introduction, transmission and circulation of polioviruses. Improvement of control in children from closed-type facilities will ensure maintenance of Russian Federation status as the country free of poliomyelitis.

The results of the construction of the first Russian ELISA system for the quantitative determination of D-antigen of 1-3 poliovirus types in the preparations of inactivated poliovirus vaccines are presented. For the first time, this kind of system is based on the use of specific antibodies of class Y (IgY) from egg yolks of immunized hens. It was shown that this ELISA system is specific, sufficiently sensitive, and can be used for quantitative determination of D-antigen of 1-3 poliovirus types in inactivated poliovirus vaccines.

Aim: Analysis of results of virological study of material from children of migrants and evaluation of intensity of immunity against polioviruses in these children., Materials and Methods: 1668 feces samples from patients with acute flaccid paralysis and contact individuals and 479 feces samples from healthy children from families of migrants, as well as 1012 blood sera of children aged 3 - 4 and 14 - 15 years living in the same territory of Russia, and 169 blood sera of children of migrants were studied. Polioviruses and non-polio enteroviruses were isolated by standard procedures recommended by WHO in 3 cell cultures - RD, L20B and Hep-2. Virus identification was carried out by microneutralization test with rabbit antisera against poliomyelitisvirus, RIVM (Bilthoven, Netherlands). For intra-type differentiation EIA and PCRwere used. Antibody titers were determined in microneutralization reaction with reference poliovirus vaccines strains in Hep-2 cell culture., Results: The frequency of detection of polioviruses in children of migrants was significantly higher than in patients with acute flaccid paralysis. In a larger percent of cases children of migrants did not have protective antibody titers against polioviruses of all the 3 serotypes., Conclusion: Migrants as a significant source of poliovirus detection may be an indicator group for detection of signs of unfavorable epidemic situation. Based on the results of epidemiologic surveillance of migrants the fact of import of wild poliovirus into North-West of Russia with the absence of poliomyelitis was proven, which confirms an important role of this form of monitoring in the system of poliomyelitis control.

Aim: Analyze the state of population immunity to polioviruses in children population of 14 administrative territories of the Russian Federation., Materials and Methods: Antibody titers against reference vaccine poliovirus serotypes 1, 2 and 3 were determined by using neutralization reaction in cell culture Hep-2., Results: Several years after the termination of conduction of National immunizations days the percent of seronegative children was shown to increase, especially to poliovirus serotype 3, in most of the territories. Possible reasons for fluctuation of geometric mean antibody titers against polioviruses in children in various territories as well as in various years in the same territory were established., Conclusion: Quality vaccine prophylaxis and control of population immunity state among children population play an important role in the maintenance of Russian Federation status as a country is free from poliomyelitis.

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.

Aim: Monitoring of implementation of international programs of poliomyelitis eradication, and measles and rubella elimination in the Republic of Belarus based on results of molecular-epidemiologic studies of 2009 - 2010., Materials and Methods: 271 viral agents isolated from children with acute flaccid paralysis syndrome, other diseases, healthy children and from sewage water within the framework of poliomyelitis control implementation were identified by serological and molecular methods. Blood sera of 528 patients with fever and rash were examined for the presence of IgM to measles and rubella virus, 418 - for the presence of IgM to parvovirus B19 and parvovirus DNA. Blood sera of 33 pregnant women and 64 children with signs of intrauterine infection were studied for IgM and IgG antibodies to rubella virus. Measles virus was isolated, N-gene sequence and phylogenetic analysis carried out., Results: The studies performed confirmed that indigenous wild polioviruses in the country do not circulate, imported wild or vaccine-related polioviruses were also not detected. Measles and rubella morbidity in the Republic of Belarus was less than 1 in 1 000 000. 2 cases of rubella (2009) and 1 case of measles (2010) was detected during adequate control level: the rate of detection of patients with fever and rash, in whom measles and rubella diagnosis was excluded by the results of laboratory examination, was more than 2 in 100 000 of the population. The etiologic agent in more than 20% of diseases with fever and rash was parvovirus B19. A single case of measles was caused by genotype D8 virus imported from India., Conclusion: The data obtained give evidence to conformance of the poliomyelitis, measles, rubella, innate rubella syndrome control implemented in the Republic of Belarus to WHO recommendations; maintenance of status of country as free from poliomyelitis and achievement of main criteria of elimination of both measles and rubella by 2010.

Addition of chitosan to inactivated trivalent polio vaccine or inactivated preparations of attenuated poliomyelitis viruses (Sabin strains) significantly increases immunogenicity of these inactivated poliomyelitis virus preparations. High neutralizing antibody titers are detected after two immunizations of mice and a single immunization of rats, as well as when the antigen dose was reduced by 4 times. Addition of chitosan as an adjuvant significantly induces cellular immunity.

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.

Aim: To assess immunization coverage against poliomyelitis and level of immunity postvaccination in children with type 1 diabetes mellitus (DM1) and rheumatic diseases., Materials and Methods: Vaccination status of 299 children with DM1 and 136 children with rheumatic diseases was determined. Serologic test using neutralization reaction was performed in 31 children with DM1 and 29 children with rheumatic diseases. Three hundred and eighty healthy children aged 3-14 years were included in the control group. All children previously received oral poliovirus vaccine., Results: During postimmunization period decompensations of main disease in children with DM1 and rheumatic diseases were not observed. There were no seronegative children to all poliovirus types revealed. Proportion of children with DM1 and rheumatic diseases seronegative to two serotypes was 12.9% and 13.8% respectively. Proportion of children with DM1 seropositive to all 3 serotypes was 54.8% that is lower than in general population (p<0.01), whereas in children with rheumatic diseases this proportion was 75.8%. In children with DM1 real proportion of immune subjects was normal--94.9% and 82.0% for pqliovirus types 1 and 2 respectively, whereas the same proportion for poliovirus type 3 was 49.7%. In children with rheumatic diseases real proportion of immune subjects was normal for poliovirus types 1 and 2, and was 72.4% for poliovirus type 3., Conclusion: Algorithms of examination of patientswith DM1 and rheumatic diseases, which allow to purposefully perform serologic evaluation as well as recommendations about additional immunization against poliomyelitis, were developed.

M. P. Chumakov Institute of Poliomyelitis and Viral Encephalitis, Russian Academy of Medical Sciences, Moscow The paper deals with the history of discovery of poliomyelitis virus by K. Landsteiner and E. Popper in 1908, the identification of three immunological types of the virus in 1949, the discovery of viral multiplication in the cultures of non-nerve cells with a cytopathogenic effect by A. Anders in 1949, the development of new diagnostic techniques, the design of inactivated poliovirus vaccine by D. Salk in 1953 and its live vaccine by A. Sabin in 1957. The advantages and disadvantages of these vaccines and the prospects for further poliomyelitis control are discussed. The characteristics and role of nonpoliomyelitis enteroviruses are considered. The most important scientific discoveries made in the study of enteroviruses are noted.

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.

41 children with chronic renal diseases (with different forms of chronic glomerulonephritis or chronic renal failure) previously vaccinated with 5 to 9 doses of oral poliovaccine (OPV) were examined. Analysis of immunity to polioviruses revealed insufficient serologic protection against all three types of polioviruses compared with general population. Algorithm of yearly serologic examination as well as a schedule of additional vaccination against poliomyelitis depending on chronic renal pathology were developed.

The ten-years experience of acute flaccid paralysis (AFP) surveillance in Belarus has been summarized. Among 456 AFP cases reported from 1996 to 2005, 11 were classified as vaccine-associated paralytic poliomyelitis (VAPP), 445--as non-polio AFP. The risk of VAPP for the period 1996-2001 was 1 case per 745,000 used doses of oral poliovaccine (OPV). For the recipients of OPV the risk was 1 case per 911,700 doses and for the first-dose recipients--1 case per 96,000 doses. The high incidence of VAPP was a reason for implementation of sequential polio vaccination schedule in 2000. Guillain-Barre syndrome dominated among non-polio AFP (39.3% of cases); more rare were traumatic neuritis (27.9% of cases), transient monoparalysis (12.1%), myelitis (7.6%). Non-polio AFP differed from VAPP by following epidemiological and virological characteristics: predominance of previously repeatedly vaccinated against poliomyelitis; development of paralysis in long-term period after vaccination; isolation of non-polio viruses belonged to three serotypes of Coxsackie B viruses (B1, B4, B6) and six serotypes of Echo viruses (6, 7, 11, 14, 24, 25) in 8.1% of cases; absence of typical for polio residual paralyses in patients who excreted vaccine polioviruses.

In connection with the cessation of the circulation of "wild" poliovirus on the territory of the European region, including Ukraine, the strategy of the vaccinal prophylaxis of poliomyelitis is reviewed. Its main aims are the creation of a high level of the specific protection of the population, the prophylaxis of vaccine-associated paralytic poliomyelitis and a decrease in the intensity of the circulation vaccine polioviruses. These aims may be achieved only by the inclusion of vaccinations with inactivated poliomyelitis vaccine (IPV) into the immunization schedule. IPV "Imovax Polio" produced by the firm "Aventis Pasteur" (France) has been shown to have low reactogenicity and high effectiveness, especially with respect to type 3 poliovirus, under the conditions of Ukraine. On the basis of our studies all children, starting from the age of 3 months, are recommended to be vaccinated first with two injections of IPV, followed by further immunization with oral vaccine.

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.

The frequency of vaccine poliovirus isolation from children aged under 3 years was studied in Belarus, a country with a high level of immunization against poliomyelitis. Antigenic and genetic characteristics of the isolated strains were studied. Vaccine poliovirus detection rate was high (11.8%). Polioviruses were isolated from children immunized recently (27.2%), immunized more than 2 months before (7.5%), and from non-immunized children (9.8%). An appreciable number (36.1%) of the isolated strains were antigenically and/or genetically modified derivatives of Sabin virus. Epidemiological data and genetic characteristics of the isolated polioviruses indicate that some of them can be sufficiently transmissive for maintaining their "silent" circulation even in a population with a high level of immunization.

MAPREC test (mutant analysis by polymerase chain reaction and restriction enzyme cleavage), evaluating the content of neurovirulent mutants with nucleotide substitution of U for C in position 472 in the 5'-nontranslated RNA region, in a virus population was used for a retrospective analysis of 3 specimens of inoculated viruses and 55 lots of type 3 oral poliovirus vaccine (OPV) prepared at M. P. Chumakov Institute of Poliomyelitis, Russian Academy of Medical Sciences, during recent 6 years. The mean content of neurovirulent mutants in inoculated viruses was 0.26 +/- 0.06%, in monovaccines 0.34 +/- 0.04% (the maximum allowable content is 1%). The method is well reproducible and detects about 0.1% mutants in the population. MAPREC test can be used instead of currently used residual virulence control on monkeys, as it detects viral preparations which were not tested on monkeys and does not reject high-quality vaccines. The protocol of using this method in combination with other methods for neurovirulence and genetic stability control of type 3 OPV is discussed.

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.

In 1991 in Tajikistan 36 cases of acute poliomyelitis were recorded (spinal form 27, bulbospinal 3, pontospinal 6 cases) in children ranging in ages from 6 months to 6 years. The outcome of the disease was fatal in 4 cases and with crude residual effects in 32 children. Out of 23 children examined, poliomyelitis virus type I was isolated from 13, antibodies to poliovirus type I in titres 1:16 to 1:1024 were detected in 21 children, ECHO 19 virus was isolated from 5 children and antibodies to this virus in titres 1:16 to 1:8192 were demonstrated in 13 children. The fresh isolates of poliomyelitis virus type I had rct+, DS+ and N+ markers. The strains of ECHO 19 virus were highly pathogenic for monkeys causing deaths of the animals within 3-4 days. It is assumed that the main causative agent of the Tajikistan outbreak of poliomyelitis was a virulent "wild" variant of poliovirus type I. The preceding or concomitant infection with ECHO 19 virus (considering the data from the literature and the demonstrated high virulence of this agent for monkeys) could exert an aggravating effect on the course of poliomyelitis or, in some cases, be an independent cause of the disease and, possibly, death of the children.

The work was aimed at the comparative study of the intensity of immunity to diphtheria, tetanus and poliomyelitis, depending on the number of injections of adsorbed diphtheria-pertussis-tetanus (DPT) vaccine and poliomyelitis vaccine, for the purpose of finding out the possibility of reducing the antigenic load given to children without diminishing the intensity of immunity. To determine the level of immunity to diphtheria and tetanus, 1900 children under school age were serologically studied by the micromethod in the passive hemagglutination test. The intensity of immunity to poliomyelitis virus was studied in 333 children by means of the neutralization test. The immunogenic properties of the diphtheria component of adsorbed DPT vaccine were found to be less pronounced than those of the tetanus component of the vaccine, which made it impossible to reduce the antigenic load by decreasing the number of vaccinations against diphtheria. The results of the study of postvaccinal immunity to poliomyelitis suggest that during the first and second year of life the course of vaccination against poliomyelitis may be reduced to 3 injections.

Eleven virus strains isolated from poliomyelitis patients in Moscow in 1973-1986 were analyzed by the method of oligonucleotide mapping of RNA. The genome of the isolates showed considerable similarity to the genomes of Sabin's vaccine strains and mainly to the vaccine strain of antigenic type 2. The conclusion was made that the sporadic cases of poliomyelitis registered in this region were etiologically linked with the vaccine strains of poliomyelitis virus. Only in one case the disease appeared in the recipient of the vaccine, in all other cases the patients were infected through contacts.

The effect of a number of nonspecific stimulators of immunogenesis (complete-Freund's adjuvant, complete adjuvant prepared from Soviet made components, arlacel with vaseline oil, aluminium hydroxide) on the immune process has been studied. The highest titers of virus-neutralizing antibodies have been obtained with the use of complete Freund's adjuvant land complete adjuvant prepared from Soviet components (X=1 : 54040 and X=1 : 40960, respectively).

The materials on the epidemiological supervision of poliomyelitis in a large city, carried out in 1972-1981, are presented. Two periods differing in morbidity rate, in the level of population immunity to poliomyelitis and in the activity of the poliovirus circulation are defined. The supervision of poliomyelitis is shown to be capable of influencing the course of the epidemic process of this infection provided that the individual elements of such supervision are correctly evaluated in different epidemic situations.

Adaptation of poliomyelitis virus type I (Mahoney strain) to the CNS of cotton rats which at the time of inoculation had been temporarily immunosuppressed with cyclophosphane is described. In the course of passages the virus properties were observed to change. The virus became pathogenic for cotton rats with normal immunologic responsiveness by the intracerebral, intraperitoneal and subcutaneous routes, as well as for white mice intracerebrally. Virions pathogenic for cotton rats were predominant in the adapted strain population.

Antibody against intracellular virus-specific proteins was produced by immunization of monkeys with extracts of cells infected with poliovirus of one of the three serotypes. Interactions of homotypic and heterotypic antibodies with labeled intracellular virus-specific proteins were studied. Immune complexes formed at this interaction were adsorbed on the surface of Staphylococcus aureus (strain Cowan I) cells, and the virus-specific proteins contained in these complexes were then analysed by polyacrylamide gel electrophoresis. The experimental results indicate the occurrence of identical (or close) antigenic determinants at least in the majority of similar intracellular proteins of polioviruses of the three serotypes.

The aim of this work was to study the state of immunity in children immunized with liquid poliomyelitis vaccine. During 1976-1981 the intensity of immunity to poliomyelitis in 653 children aged 1-3 years was studied. The study showed that at the period when liquid poliomyelitis vaccine was used the share immune to polioviruses, types 1 and 2, constituted 89.4% and 98.0%, respectively, as compared with 67.0% and 68.0% at the period when sugar-coated live dried poliomyelitis vaccine was administered. Changes in such epidemiological characteristics, as the percentage of persons with antibodies to poliovirus, were particularly essential in the age group of 1-2 years. In 1979 persons with antibodies to type 1 poliovirus constituted 94.0% as compared with 44.0% in 1976, while the percentage of persons found to be seronegative in respect of antibodies to polioviruses, types 1, 2 and 3, decreased 5-7 times. The quality of immunization carried out at the period, when liquid poliomyelitis vaccine was used, was shown to influence the size of the immune share, while having no effect on the geometric mean of the titer of antibodies to polioviruses.

A new method of solid-phase analysis of viral antigens in which St. aureus, strain Cowan 1, was used as a label is described. The result of analysis is read visually by bacterial agglutination. The degree of agglutination of the staphylococcal diagnosticum corresponds to the amount of the antigen bound with antibodies immobilized on the solid phase. Staining of Staphylococcus with methylene blue simplifies reading of the results. The method has been shown to be sufficiently simple, specific, sensitive, and may be used for diagnosis of different infections diseases.

It was shown that titers of the neutralizing activity of fecal extracts (coproantibody, CA) to poliomyelitis virus type II in the course of four administrations of live trivalent poliovaccine in drops directly into the mouth and in capsules were higher than CA titers to poliomyelitis virus types I and III. Particularly low CA titers to poliovirus types I and III were in children given the vaccine in the capsule, that is directly into the gastro-intestinal tract. Accordingly IgA levels in fecal extracts in this group of children were lower than in those given the vaccine in drops. In children of both groups no IgG of IgM (0.24 IU/ml) could be found in fecal extracts.

A microfluorimetric method for the determination of the quality of FITC-labeled antisera with the determination of the titer and the optimal working dilution in the FA test is described. Besides, the method permits to determine the confidence factor for any dilution of FITC-antiserum and to compare different lots.

Antibodies from the yolk of eggs of chicken immunized with enteric viruses (simian rotavirus SA 11, poliomyelitis virus type 2, and Coxsackie B2) were obtained. The time course of the emergence and amplification of antibody in the yolk was followed for several months by neutralization tests and enzyme immunoassay. The long-term persistence of a high antibody level in the yolk, the simplicity of generation of large amounts of chromatographically pure preparations, as well as specificity of chicken immunoglobulins open ways for their employment in different test systems for the detection and identification of enteric viruses.

A possibility of obtaining the diagnostic specific sera with a high titre against the poliovirus, type I, was studied experimentally. Five different immunization schemes by the same antigen were tested in parallel experiments. A method of the viral antigen (both of the concentrated and of the unconcentrated) mixed with complete Freund's adjuvant injection into the popliteal lymph nodes with the subsequent single reimmunization proved to be most effective. In this way it was possible to obtain type-specific sera with a high titre (1:20 000--1:40 000) in the course of five weeks.

The intratypic antigenic differentiation of poliovirus strains isolated from sick or healthy children in Mali in 1975-1976 was performed. The method is based on the use of cross-adsorbed sera in the neutralization tests in which the virus is titrated by the plaque procedure or by the cytopathic effect. All the examined strains of serologic types I, II, and III were distinguished by the antigenic structure from the vaccine strains and were classified as "wild". Quantitative differences in the antigenic structure of type I strains isolated in different towns of Mali were found.

Studies of the genetic markers of 39 (57.4%) strains of poliomyelitis virus type I isolated from sewage showed 7 of them to have genetic markers ret+40, Gu+, A+, Ag+ (Mahoney, Koñkov), 3 to be ret+40, Gu+, A+, Ag+ (Koñkov, Sabin), and 10 to be ret+40, Gu-, A-, Ag- (LSc 2ab). Among 20 (29.4%) strains of poliovirus type II two were ret+40, Gu+, A+, N+, Ag+ (MEF-1), and 2 were ret-40, Gu-, A-, N-, Ag- (P712 Ch2ab), and among 9 (15.2%) strains of type III only one (Saukett) had the genetic markers ret+40, Gu+, A+, Ag+. In the other 43 poliovirus strains under study the genetic markers did not correlate with each other. The possibility of using counter immunoelectrophoresis alongside with gel precipitation test for the study of antigenic intratype differences of polioviruses was demonstrated.

Experiments in cotton rats weighing 60-80 g orally vaccinated with gradually decreasing doses of live poliovaccine type II causing immunological changes of varying intensity demonstrated the attenuated poliomyelitis virus to penetrate the CNS, lungs, and spleen quite regularly. The virus could be isolated from the cytoplasmic extracts of these organs for up to 45 days, from the spleen for 60 days. Penetration of the virus into the CNS did not result in the development of disease. The long-term persistence of the virus in the organs was accompanied by the development of inflammatory-degenerative changes in the CNS and in some cases by pneumonia.

The data have been obtained which indicate that the effectiveness of vaccination with live trivalent poliomyelitis vaccine may be increased and 90--100% of the vaccinated infants under 1 year of age may develop marked resistance of the alimentary tract and high antibody titers in the blood serum to the threee types of poliomyelitis virus in the course of 3 vaccinations. Some regularities of the formation of immunity to individual poliomyelitis virus types in the course of 4 vaccinations with trivalent vaccine were revealed and specified. The results indicate that the contact of vaccine virus with the oropharyngeal tissues during immunization has a favourable effect on the development of immunity. Vaccination of infants under 1 at 6-week intervals between vaccine feedings creates solid immunity in 90--100% vaccines. Administration of the next vaccine dose 6 weeks after the previous one stops multiplication of the dominating type of vaccine virus and prevents its long-term passage in the intestinal tract decreasing the probability of emergence of vaccine virus variants with increased pathogenicity.

The results of examinations of blood sera from normal children for the presence of antibody to polioviruses after two courses of mass vaccinations were carried out according to epidemiological indications although differing in duration of the campaign and the range of the child populations involved, are presented. The advantages of simultaneous mass vaccinations covering children from 2 months to 7 years of age have been demonstrated.

In addition to report I (ZHMEI, 1977, No. 1) a study was made of 9 more schemes of rabbit immunization with the poliomyelitis virus, type I, for the purpose of obtaining the neutralizing sera of high titre. Vitamins A and C were used in the experiments in the capacity of the activators of the organism reaction; Freund's adjuvant of different make was tested; different reimmunization periods and different amounts of the adjuvant were administered. Titration of rabbit sera in the process of immunization and reimmunization showed immunization into the lymph nodes with the subsequent single reimmunization in one month to be the most effective and economical method of obtaining high effective sera.

A uniform program of the epidemiological supervision of poliomyelitis must be worked out for every administrative territorial unit. This program should include the early and complete detection of all cases of this infection, irrespective of their severity; the analysis of the quality of vaccination; the determination of the immune status of the child population; the characteristic of the poliovirus circulation.

The results of prolonged dynamic observations on the state of herd immunity against poliomyelitis virus in an industrial city are given. The survey covered 1304 children. The data thus obtained, when synchronized according to years, seasons, the age of the surveyed children and the methods used in the survey, indicated that in every age group 20-30% of children had no antibodies to group I poliomyelitis virus and 30% of children had no antibodies to group III poliomyelitis virus. The geometrical mean of antibody titers to different types of the virus fluctuated from 1.8 to 4.6 log2, the lowest value being obtained for the titer of antibodies to type III poliomyelitis virus. During the whole period of immunological control (1974-1978) no mass circulation of poliomyelitis virus and no outbreaks of poliomyelitis were registered despite the fact that a considerable proportion of children having no antibodies to one or several types of the virus was constantly present among the most susceptible part of children.