[The spread and biological properties of epidemic influenza viruses A and B strains circulating in the 2006-2007 season in Russia].

The epidemic upsurge of influenza morbidity in the 2006-2007 season in Russia was caused by the active circulation of influenza A(H1N1), A(H3N2) and B viruses. The Center for Ecology and Epidemiology of Influenza studied 259 epidemic strains; All the strains were isolated on MDCK cell cultures. Influenza A(H1N1) viruses (n = 101) were antigenic variants of the references A/New Caledonia/20/99 and A/Solomon Islands/3/06. Influenza A(H3N2) viruses (n = 98) were antigenic variants of the references A/California/7/07 and A/Wisconsin/67/05. Twenty four influenza B virus strains were drift variants of the reference BI Shanghai/361/02 - lineage B/Yamagata/16188 and 36 were related to A/Malaysia/2506/05 - lineage B/Victoria/2/87). All the isolated strains actively interacted with human erythrocytes of the blood groups 0(I) and A(II) and very slightly with chicken ones. Twenty-two (48%) A(H1N1) strains and 19 (35%) A(H3N2) strains which were resistant to rimantafine were revealed. Studies of the donor sera collected in Moscow and the Moscow Region, the Jewish Autonomous Region, and Primorye revealed antibodies to today's strains; the level of antibodies in the preepidemic period depended on the region and strain. A study of changes in antibody formation in different periods of an epidemic process showed a rise in antibodies mainly to influenza A and B virus strains circulating in this period.

[Epidemic strains influenza viruses A and B in the 2005-2006 season in Russia].

Investigations indicated that the epidemic upsurge of influenza morbidity in the 2005-2006 season in Russia was caused by the active circulation of influenza viruses A and B. The Center for Ecology and Epidemiology of Influenza, D. I. Ivanovsky Institute of Virology, Russian Academy of Medical Sciences, studied 182 epidemic strains. A hundred and thirteen influenza viruses A(H3N2) were similar to the reference A/California/07/2004 or were its antigenic variants. Thirteen influenza virus A(H1N1) strains that were antigenic variants of the reference A/New Caledonia/20/99 were isolated in sporadic cases. Influenza viruses B were similar to B/Malaysia/2506/2004--lineage B/Victoria/2/87). All the strains were isolated in the MDCK cell culture. Comparative study of the sensitivity of the chicken embryo (CE) and MDCK isolation system to the 1999-2006 epidemic strains showed that CE tropism was least pronounced in influenza viruses A(H3N2). Analysis of the 2002-2006 strains demonstrated that influenza viruses A reacted actively with human erythrocytes of the blood groups 0(I) and A(II) and very slightly with chicken ones. Eighty-five influenza virus A(H3N2) strains from the 2005-2006 epidemic season were investigated for rimantadine susceptibility. The frequency of rimantadine-resistant influenza virus A(H3N2) strains was 38.0%. Studies of 79 paired sera from patients revealed a rise of antibodies to influenza viruses A(H3N2) and B in 25.9-33.3 and 20.7-23.8% of cases, respectively. There was an increase in antibodies to influenza viruses A and B in the sera collected from donors in Moscow and its region in September 2005 to June 2006.

[Rimantadine and arbidol sensitivity of influenza viruses that caused epidemic morbidity rise in Russia in the 2004-2005 season].

The study of the activity of arbidol against epidemic influenza A and B virus strains (2002-2005) in the cultured MDCK cells showed the higher sensitivity of enzyme immunoassay than that of hemagglutination test. The influenza A virus strains tested, including those resistant to rimantadine (5 microg/ml), were sensitive to arbidol (10 microg/ml). The population of influenza B virus strains was heterogeneous in this indicator, 43% of the strains being less sensitive to arbidol. There was an increase in the number of rimantadine-resistant influenza A(H3N2) virus strains (10-18%) in our country during 3 epidemic seasons. The sequencing analysis of protein M2-endoding gene revealed the amino acid replacement of serine by asparagine in position 31, which is characteristic of rimantadine-resistant strains. Arbidol in combination with rimantadine potentiated the effect of viral reproduction in the cultured cells, as compared with the effect produced by the same concentrations of the drugs used alone.

[Internal epidemic influenza virus proteins: isolation and investigation].

The internal influenza virus proteins M1 and RNP free from surface protein impurities were isolated from subviral particles (virions free from HA and NA ectomenes). The spikeless particles had no propensity to aggregate in the solution at pH 5.0 as compared with native viruses. The subviral particles of B/Hong Kong/330/01 influenza virus, which belonged to B/Victoria/2/87-lineage, were obtained by proteolytic treatment with the enzyme bromelain under the same conditions as in cases of influenza B viruses of B/Jamagata/16/88 lineage. A chromatographic analysis of the tryptic hydrolyzates obtained for matrix (M1) proteins of A(H1N1) and A(H3N2) influenza viruses revealed differences that were greatest between the protein M1 molecules isolated from influenza viruses of different subtypes of hemagglutinine. These findings suggest there are variations in the structure of this conservative internal viral protein M1 during evolution.

[Isolation of influenza A/H5N1 virus strains from poultry and wild birds in West Siberia during epizooty (July 2005) and their depositing to the state collection of viruses (August 8, 2005)].

Six strains of influenza AH5N1 virus were isolated, by using PS and MDCK continuous cell lines from poultry and wild birds, which were collected on July 28, 2005 in the samples taken from 5 examines species of wild birds in the Novosibirsk region during the epizootic outbreak with a high mortality. The strains were identified by means of HIT, RT-PCR, and microchip-based techniques. Two strains, A/Grebe/Novosibirsk/29/05 (H5N1) and A/Duck/Novosibirsk/56/05 (H5N1), were deposited to the Russian State Collection of Viruses (Registration Nos. 2372 and 2371, respectively) with the priority date 08.08.2005. Positive results in RT-PCR for influenza A/H5N1 virus detec- tion were obtained in 100% of the samples from dead and sick poultry; 93% from the clinically healthy poultry kept together with sick one; positive results ranged from 0 to 36%. Sequencing established the identity of genetic characteristics of strains isolated for wild birds and poultry as well as their affiliation to high pathogenic avian influenza (HPAI). Phylogenetic analysis revealed a high homology of hemagglutining of West-Siberian strains and strains isoolated from bar-headed gooses (Eulabeia indica) on the Qinghai Lake (Western China) in the 2005 spring.

[Characterization of epidemic influenza virus A(H3N2) strains circulating in Russia in the 2003-2004 epidemic season].

Studies indicated that the epidemic rise in the incidence of influenza was caused by its virus A (H3N2) circulation in Russia in the 2003-2004 season. The Center of Influenza Ecology and Epidemiology investigated 101 epidemic strains isolated the MDCK culture. Antigenic analysis showed that all viruses A(H3N2) were similar to the reference virus A/Fujian/411/02(H3N2) and only 5 strains slightly differed from the latter. Twelve (14%) strains resistant to rimantadine at a concentration of 0.5 mg/ml were identified. Investigation of paired sera from the patients demonstrated a rise of antibodies to the references of influenza virus A(H3N2) in 68.7% of cases and a less increase in those to influenza viruses A(H1N1) and B. The active circulation of A(H3N2) viruses was due not only to changes in their antigenic structure, but also to the low level of antibodies to these viruses, as shown by the analysis of donor sera.

[The properties of the epidemic influenza viruses A and B strains circulating in Russia in the 2004-2005 epidemic season].

The epidemic upsurge of influenza morbidity in Russia in 2004-2005 was caused by the active circulation of influenza A(H3N2) and B viruses. A hundred and sixty-six epidemic strains were studied. All the strains were isolated in the MCK cell culture. Influenza A(H3N2) viruses (n=77) were antigenic variants of the reference A/Fujian/411/ 2002 and A/California/7/2004 strains. Three influenza A(H1N1) viral strains that were antigenic variants of A/New Caledonia/20/99 strains were isolated in sporadic cases. Influenza B virus strains (n=83) were antigenic variants of the reference B/Shanghai/361/02--lineage B/Yamagata/l6/88. In addition, 3 antigenic variants of B/Hong Kong/ 330/2002 (lineage B/Victoria/2/87) strains were isolated. Nine (20%) strains resistant to rimantadine at a concentration of 5 microg/ml were identified. Chromatographic analysis of B/Shanghai/361/02 and BIHong Kong/330/01 viral protein M1 trypsin hydrolysates revealed differences in the profiles of chromatograms of influenza A virus proteins M1. Examination of 121 pair sera from patients revealed an increase in antibodies to influenza A(H3N2) viruses in 10-21% of cases and to influenza B viruses in 20-36% of cases.

[The rimantadine sensitivity spectrum in influenza A viruses circulating in the 2002-2004 epidemic seasons].

A total of 200 influenza A virus strains were studied. Among them there 32 strains of A(H1N1) and 84 strains of A(H3N2) from the 2002-2003 epidemic season and 84 strains of A(H3N2) from the 2003-2004 epidemic season. Most rimantadine-sensitive strains whose infectivity and hemagglutinating activity were found to decrease by the drug given at a concentration of 0.5 microg/ml. In terms of infectivity and hemagglutinating activity, the number of rimantadine-resistant strains of A (H1N1) was equal to 9.0% for A(H1N1) influenza viruses and to 10.0 and 14.0% for A (H3N2) influenza viruses in different seasons, respectively.

[Influenza viruses which preconditioned the epidemic rise in Russia in 2002-2003. A resumed circulation of influenza viruses similar to V/Victoria/2/87]. / Osobennosti virusov grippa, obuslovivshikh épidemicheskii pod"em zabolevaemosti v Rossii v 2002-2003 gg. Vozvrat tsirkuliatsii virusov grippa, podobnykh V/Viktoria/2/87.

According to research, the epidemic rise of influenza was preconditioned, during 2002-2003, in Russia by the circulation of influenza A(H1N1), A(H3N2) and B viruses. The Center of Influenza Ecology and Epidemiology undertook a study of 178 epidemic strains: 41 strains A(H1N1), 116 strains A(H3N2) and 21 strains of influenza B were among them. All strains were isolated in the MDCK cell culture. A simultaneous isolation in embryonated eggs as well as changing of the isolation system from MDCK to embryonated eggs were found to be effective only for influenza A(H1N1) viruses. According to the antigenic analysis, all A(H1N1) viruses were variants of the etalon A/New Caledonia/20/99. The A(H3N2) viral strains' population was heterogeneous by its antigenic properties: among its isolates, there were variants similar to the etalons of A/Moscow/10/99 and of A/Panama/200/99 as well as strains, which weakly reacted with sera of both above etalons; possibly the latter were close to the etalon of A/Fujian/411/02. All epidemic strains of influenza B virus belonged, according to the antigenic properties of hemagglutinin, to the virus group of B/Victoria/2/87-like and were antigenic variants of the etalon of B/Hong Kong/22/01. This confirmed that influenza B viruses with the antigenic hemagglutinin structure of the virus group of B/Victoria/2/87-like, which were not present in Russia for more than 10 years, re-entered the active circulation. An analysis of antigenic properties of neuraminidases (NA) of the mentioned epidemic strains showed their different degrees of relationship with the NA etalons of both evolutionary groups, i.e. B/Victoria/2/87 and B/Yamagata/16/88-like. A study of paired sera obtained from patients showed a growth of antibodies to the etalons of influenza A(H1N1), A(H3N2) and B viruses of the season in question, which confirmed the virology data.

[Evaluation of influenza vaccine Vaxigrip in the combined immunization of conscripts during influenza seasons of 2002-2003]. / Opyt primeneniia grippoznoi vaktsiny Vaksigrip pri sochetannoi immunizatsii prizyvnikov srochnoi sluzhby v épidemicheskom sezone 2002-2003 gg.

The immunization properties of the influenza vaccine Vaxigrip, used in combination with vaccines against pneunococcal infection and hepatitis A (respectively, Pneumo 23 and Avaxim), were evaluated. In Central Russia in one of the units of the internal forces of the RF Ministry of Internal Affairs 3 groups totaling 755 servicemen were formed, depending on the complex of the introduced vaccines. Active medical observation and the registration of the complaints of the vaccinees at the postvaccinal period did not reveal unusual reactions and complications in none of the groups under observation. In the evaluation of the level of specific antibodies to the circulating influenza viruses prior to vaccination the low level of collective protection to influenza B virus was determined: protective antibody levels were registered only in 14-18% of the servicemen, while the corresponding data with respect of influenza viruses A(H1N1) and A(H3N2) were 45-50% and 56-63% respectively. At the same time, in seronegative persons the vaccine Vaxigrip exhibited high immunogenic activity with respect of all 3 influenza strains; seroconversion to them was determined in 84-92% of the vaccines, and the level of protective antibody titers before the beginning of the epidemic season was 86-99% in the whole of the group. The characteristics of the prophylactic effectiveness of the vaccine Vaxigrip in relation to the influenza virus infection level 1 were 4.7 (index) and 79% (coefficient). In addition, the frequency of influenza cases, clinically pronounced and confirmed by laboratory methods, in patients who had been immunized with 3 vaccines was 6.7%, which was 10.3 times less frequent than number of cases in the groups of comparison (68.2% on the average). The coefficient of epidemiological effectiveness of the prophylaxis of influenza was 90.2%. The complex use of 3 preparations did not affect the immunization properties of the vaccine Vaxigrip.

[The use of bromelain in obtaining the subviral particles of influenza A and B viruses]. / Ispol'zovanie bromelaina dlia polucheniia subvirusnykh chastits virusov grippa A i B.

Subviral particles of modern strains of influenza A viruses, i.e. A/New Caledonia/20/99 (H1N1), A/Moscow/10/99 (H3N2), reassortant X-31 (subtype H3N2) and B/Sichuan/379/99, were obtained by using two preparations of bromeline ("Sigma Co., Catalogues' Nos. B2252 and B5144). A selective ability of bromeline B5144 was detected to the proteolytic splitting of hemagglutinin of influenza A and B viruses. An influence of enzyme B5144 produced on influenza B viruses brought about an appearance of subviral particles. As for influenza A(H1N1) virus, the above enzyme did not have any impact on it under the similar experimental conditions. An incomplete effect was noted for the influenza A(H3N2) virus with particles (with intact external coatings) being found in the reaction mixture. Enzyme B2252 was found to be effective in respect to all viruses selected for testing, however, the highest effect was noted for influenza A(H1N1) and B viruses.

[Spread and properties of epidemic influenza A and B virus strains accountable for morbidity in Russia during 1999-2002]. / Rasprostranenie i svoistva épidemicheskikh shtammov virusov grippa A i B, vyzvavshikh pod''em zabolevaemosti v Rossii v 1999-2002 gg.

The strains of influenza A -A(H1N1), A(H3N2) and B viruses were shown in the paper to have been circulating in Russia in 1999-2002. A co-circulation of viruses of 2 to 3 types was detected in all epidemic seasons. A majority of strains was isolated on the culture of cells MDCK. A study of epidemic strains revealed the predominance of viruses A(H3N2) in 1999-2000, the predominance of viruses A(h1N1) in 2000-2001, and the predominance of influenza B viruses in 2001-2002. According to the conducted antigenic analysis, all A(H1N1) isolates were similar to the etalon A/New Caledonia/20/99. The antigenic drift of hemagglutinin of A(H3N2) epidemic strains was oriented towards the etalons of A/Sydney/5/97--A/Moscow/10/99; while in influenza B viruses it was oriented towards the etalons B/Beejing/184/93--B/Yamanashi/166/98--B/Sichuan/379/99. Sequencing of hemagglutinin gene HA1 showed certain difference in the gene structure of epidemic strains A(H1N1) and A(H3N2) versus the etalon ones, which were registered, including at antigen sites. An analysis of paired sera obtained from patients confirmed the virologic findings, i.e. it detected a growth of antibodies to viruses that circulated during an actual season.

[Differences in oligomerization of nucleocapsid protein of epidemic human influenza A(H1N1), A(H1N2) and B viruses]. / Razlichiia v oligomerizatsii nukleokapsidnogo belka épidemicheskikh virusov grippa cheloveka A(H1N1), A(H3N2) i B.

A comparative analysis of involving the nucleocapsid protein (NP) into shaping-up of SDS-resistant oligomers was carried out presently in circulating epidemic strains of human influenza, viruses A and B. The study results of viral isolates obtained from clinical samples and recent standard strains revealed that the involvement of NP in the SDS-resistant oligomers, which are different in various subtypes of influenza A viruses. According to this sign, the human viruses A(9H3N2) are close to the avian ones, in which, as proved by us previously, virtually the entire NP transforms itself into the oligomers resistant to SDS. About 10-20% of NP are involved in shaping-up the virus influenza A(H1N1) of SDS-resistant oligomers. No SDS-resistant NP-oligomers were detected in influenza of type B. It is suggested that the prevalence of human viruses A(H3N2) in NP-oligomers are the peculiarities of NP structure and of the presence of the PB1 protein from avian influenza virus.

[Epidemiologic and economic efficacy of massive prophylaxis of influenza and other acute respiratory viral infections using curantil in Moscow enterprises]. / Epidemiologicheskaia i ékonomicheskaia éffektivnost' massovoi profilaktiki grippa i drugikh ostrykh respiratorno-virusnykh infekstii na Moskovskikh predpriiatiiakh s pomoshch'iu kurantila.

AIM: To evaluate epidemiological and cost-effect value of curantil in "in-office" prophylaxis of influenza and acute respiratory diseases (ARD) in Moscow. MATERIAL AND METHODS: Curantil was given once a week for 4-5 weeks in a dose 50 mg with 2-3-week intervals in autumn peaks of ARD and influenza epidemics. Participation of the population was 50-70% maximum. Prevailing influenza viruses causing epidemic in 1990-1991, 1991-1992 were A(H3N2) and B, respectively; ARD were caused by parainfluenza viruses, PC, P, mycoplasma etc. Efficiency index and rate were calculated: EI = a/b; ER = (a-b)/a x 100 where a--morbidity in the test group, b--in the control. Cost effectiveness was estimated by sick leaves pays for workers equal to the number protected by curantil and wages for those who worked instead of the ill workers or by the cost of the saved production. RESULTS: Epidemiological efficiency at enterprise 1 in autumn 1990 was the following (70% covarage): EI = 4.4, ER = 77.2%; in winter epidemic EI = 2.7, ER = 62.4% (covarage 50%). Close results were obtained in the next epidemiological season. In autumn in the enterprise 2 EI = 3.9; ER = 74.3%. Curantil prophylaxis at enterprise 1 protected 53 workers and saved 11278.88 roubles. CONCLUSION: Curantil effectiveness, wide spectrum of action, safety in oral administration 50 mg once a week make curantil convenient for mass prevention of influenza and ARD.

[Antineuraminidase activity of inactivated influenza vaccines in elderly people]. / Antineiraminidaznaia aktivnost' inaktivirovannykh grippoznykh vaktsin u lits pozhilogo vozrasta.

The antineuraminidase activity of 5 inactivated split and subunit influenza vaccines (IIV) was studied in individuals aged above 65 years. Postvaccinal antibody titers were determined in the lectin test. All the vaccines were shown to have a high antigenicity, by providing high titers of neuraminidase antibodies in most vaccinated persons: The mean geometric titers (MGT) to influenza viruses A(H1N1) and A(H3N2), and B were 7.4-8.0, 8.5-9.2, and 6.8-8.5 log2, respectively. Neuraminidases showed a higher activity in Vaxigrip-vaccinated persons in terms of both the rate of MGT increases and seroconversion that was 78-84%. The parameters of the anti-neuraminidase (anti-NA) and anti-hemagglutinating (anti-HA) activities of IIV are summarized in the paper. There was a high coincidence of the results of both tests. At the same time it was shown that the postvaccinal humoral immune response might be directed only to one of the surface influenza virus proteins. The highest rate of seroconversions as to the surface antigens of all three influenza viruses was observed in Vaxigrip-vaccinated persons. The paper presents the results of comparison of the levels of MGT of antibodies to both viral surface proteins for all vaccinated with IIV, for those vaccinated who were infected during an epidemic season and a place group. The findings confirmed the value of higher titers of postvaccinal antibodies against influenza infection and illness.

[Properties of influenza A and B, isolated from chick embryos and in MDCK cell culture]. / Svoistva virusov grippa A i B, vydelennykh na kurinykh émbrionakh i v kul'ture kletok MDCK.

MDCK culture was used along with the traditional chicken embryonated eggs (CEE) for improving the efficiency of isolation of epidemic influenza A and B viruses from clinical material. The number of influenza viruses isolated in both systems in epidemic seasons of 1997-1998 and 1998-1999 was as follows: 1 in MDCK and 21 in CEE for influenza A(H1N1), 56 and 7, respectively, for influenza A(H3N2), and 4 and 2 strains, respectively, for influenza B viruses. Influenza A viruses were heterogeneous by sensitivity to various erythrocytes, thermal stability of hemagglutinins, and transfer to another culturing system. Unlike the strains isolated in CEE, cultural viruses possessed a thermolabile hemagglutinin and more actively reacted with human and guinea pig erythrocytes. Evolution of influenza A(H3N2) viruses which is due mainly to changes in the hemagglutinin structure seems to be directed towards greater tropism to mammalian but not avian cells. Influenza B viruses are more homogeneous by antigenic and biological properties.

[Evolution of influenza B viruses at the end of the 20th century]. / Evoliutsiia virusov grippa B v kontse XX veka.

Influenza B viruses (48 strains) isolated in Russia in 1992-2000 have been investigated. The majority (29 strains) were isolated in 1994-1995. The strains were isolated in embryonated eggs and MDCK cells. Study of their antigenic properties showed that all of them belonged to an evolutionary group B/Jamagata/16/88-like viruses. Antigenic drift in the hemagglutinin (HA) of epidemic strains isolated in Russia was the same as in reference strains of this evolutionary group. HA proteins of isolated and reference strains differed by 8-12 amino acid sequence positions. Paired sera of patients with influenza-like diseases collected during this decade were tested. Seroconversions to B/Jamagata/16/88-like strains were discovered for during the entire period of observation, while seroconversions to reference strains of the B/Victoria/2/87 group only in 1999-2000 season, which can be regarded as activation of these viruses in Russia.

[Variability and prevalence characteristics of Influenza A virus (H1N1) in period 1990-1998]. / Izmenchivost' i osobennosti rasprostraneniia virusa grippa A (H1N1) v period 1990-1998 gg.

Circulation of influenza A(H1N1) viruses in Russia and CIS countries had a wave-like pattern with period of silence in 1990-1995 and activation in 1995-1998, when these viruses were isolated together with A(H3N2) and B viruses. Antigenic drift of epidemic strains' hemagglutinin (HA) was directed to alteration of HA in reference strains A/Texas/36/91, A/Johannesburg/82/96, and A/Beijing/262/95. A/Moscow/17/98 strain similar to A/Beijing/262/95 was isolated on MDCK cells for the first time in European Russia. This means that A/Beijing/262/95 (H1N1) spread sporadically in the country at that time. Comparative analysis of HA thermosensitivity of influenza A(H1N1) strains of 1977-1998 showed a tendency to increase of their thermal stability. The sensitivity of erythrocytes of different animals to A(H1N1) strains isolated during the same epidemic season was different. Differences in amino acid sequences of epidemic strains' HA varied from 5 to 14 sites in comparison with the reference strains, depending on the reference strain and year of isolation.

[Characteristics of epidemiological strains of influenza A virus (H3N2) isolate in 1997-1999. Virus A/Moscow/10/99--a candidate to become the vaccine strain]. / Kharakteristika épidemicheskikh shtammov virusa grippa A(H3N2) 1997-1999 gg. izoliatsii. Virus A/Moskva/10/99--kandidat v vaktsinnyi shtamm.

Antigenic properties of influenza A(H3N2) viruses isolated during two epidemic seasons 1997-98 and 1998-99 in Russia are analyzed. All strains are antigenic variants of the reference strain A/Sydney/5/97. Characteristics of epidemic strain A/Moscow/10/99, proposed by WHO expert committee as vaccine strain for 1999-2000 have been studied. This strain, isolated on chick embryos, is characterized by high reproductive activity in chicken embryos with an infectious titer of 10(6) EID50/0.2 ml, easily adapts to MDCK culture, and has a thermostable hemagglutinin.