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The paper gives the results of monitoring the circulation of influenza viruses in the 2010-2011 season, that covers the second year of circulation of pandemic A(H1N1)v virus strains, and their interaction with seasonal A (H3N2) and B strains. Unlike the previous season, the beginning of an increase in morbidity was recorded in January 2011; its peak in the most of contiguous areas was noted at 5-7 weeks of 2011, with its further decline to threshold levels at week 11 of 2011. Preschool and school children were most involved in the epidemic process. Three influenza virus strains (A(H1N1)v, A(H3N2), and B) were found to circulate. Differences were found in the level of participation of the isolated strains in individual areas of the Russian Federation. Detailed typing of the isolated strains determined the compliance of the vast majority of them with vaccine viruses. The pandemic influenza A(H1N1)v virus strains retained their susceptibility to oseltamivir and were resistant to rimantadine. The participation of non-influenza acute respiratory viral infection pathogens was estimated as follows: 11.9% for parainfluenza viruses, 5.9% for adenoviruses, and 3.5% for PC viruses, and 0.7% for pneumonia Mycoplasma, which was comparable with the previous epidemic seasons.

The paper gives the results of calculation-theoretical studies estimating the effect of the etiotropic agent Relenza (in preventing influenza in its susceptible patients an in treating patients ill with influenza) on the epidemic of pandemic A(H1N1)/2009 influenza in a large city of Russia. The values of its effect (the number of prevented cases of influenza and that of prevented deaths from its complications) have been calculated on a computer, by applying a modified PSEEI2RF influenza epidemic model (a Russian Baroyan-Rvachev model) with the A(H1N1)/2009 influenza pathogen that dominated in the 2009-2010 season in many countries of the world. Predictive estimates of the action of Relenza on the epidemic of A(H1N1)/2009 influenza have been obtained for 5 scenarios while implementing measures to treat patients with the illness and to prevent its susceptible patients in a large city with a population of one million. In conclusion, there are results of predicting the number of prevented A(H1N1)/2009 influenza cases and damage estimates for 6 cities of Russia due to the massive use of the antiviral drug Relenza.

Research Institute of Influenza, Ministry of Health and Social Development of Russia, Saint Petersburg The characteristics of the isolation of pandemic influenza A(H1N1)v viruses were studied on chick embryos (CE) and MDCK cell culture. The materials (nasal swabs and autopsies) were collected in different regions Russia in the period from 20 July to 30 December 2009. The paper gives the data of the antigenic analysis of isolates, their capacity to multiply in different species-specific and tissue cell cultures. The viruses isolated on CE were shown to have higher hemagglutination titers and to be more stable. Isolation from the autopsies was effective only on CE. All the test cell lines other than MDCK were insensitive to the isolated pandemic influenza strains. The antigenic analysis showed no significant antigenic drift of the viruses isolated during the first wave of the pandemic in the Russian Federation.

The paper describes a simple, rapid screening of samples potentially containing Crimean-Congo hemorrhagic fever (CCHF) virus strains, by applying the restriction analysis of amplicones, for the differentiation of CCHF virus genotypes that are characteristic of Europe from virus biovariants uncharacteristic of this area, this technique requiring no sequence at the first stage. For this screening, the authors propose to use the PCR fragment of CCHF L segment that comprises a variable region, as well as Alul and Haelll restriction endonucleases. The screening scheme proposed for samples potentially containing CCHF virus may aid investigators to monitor in order to detect uncharacteristic genotypic virus variants in the Russian Federation and other European countries.

The paper describes the specific features of the 2009-2010 epidemic season in Russia and the world, which are due to the wide spread of a new pandemic strain of influenza A(H1N1)v virus. There is an unusual early upsurge in the incidence of influenza and acute respiratory viral infection (ARVI) (in October-November 2009) with its peak at weeks 45 to 48 of the year with a succeeding reduction to the seasonal values by its end. The circulation of influenza B virus strains was recorded in February-April 2010, which was responsible for the higher epidemic thresholds of morbidity in a number of Russia's regions. A study of the antigenic properties of the strains defined their relationship to the reference strains A/California/07/2009 (H1N1)v and B/Brisbene/60/2008. There were strains with amino acid substitutions at position 222 of hemagglutinin in the population of pandemic influenza A(H1N1)v virus. The strains of the new pandemic influenza A(H1N1)v virus were resistant to remantadine and susceptible to oseltamivir, zanamivir, and arbidol. The influenza B virus strains were susceptible to oseltamivir, zanamivir, and arbidol. The proportion of pathogens of some ARVIs was as follows: parainfluenza viruses, 9.8%; adenoviruses, 5.5%; respiratory syncytial virus, 4.8%; and Mycoplasma pneumonia, 0.6%. There is evidence that there is a need for further monitoring of influenza viruses in Russia.

The paper presents the results of the first Russian experience in evaluating the sensitivity of the epidemic and pandemic influenza virus strains, circulating in the period 2009-2010, to the anti-neuraminidase drug zanamivir. A complex of studies, including enzyme immunoassay, fluorometric assay and partial sequence of the neuraminidases (NA1 and NA2) from influenza A virus strain, was applied. The findings Indicate that all the test strains, including those resistant to oseltamivir, were susceptible to zanamivir. The latter is recommended by the WHO for the prevention and treatment of influenza in pregnant women.

The paper presents the data of an investigation of the genetic polymorphism of the pol gene encoding viral integrase (IN) in a HIV subtype A infected population in the Lipetsk Region. The investigators analyzed 32 virus subtype A samples obtained in 2002-2007. Polymorphism at the codons associated with IN resistance to chemicals was observed in 7 virus variants. The found substitutions had a pattern of genetic polymorphism and were unassociated with resistance in 6 patients with the test subtype A population. At the same time, minor RAL resistance mutation was revealed in 1 (3.1%) virus variant while the similar mutations in the subtype G population were about 10%.

The paper gives information on the first case of Crimean-Congo hemorrhagic fever detected in a female resident of the Anapa District, Krasnodar Territory, in 2005 in the past 57 years.

The basic trends in the evolution of influenza A and B in the Russian Federation during the epidemic seasons of 2006-2009 were studied on the basis of an antigenic analysis of 1774 Influenza isolated at the Research Institute of Influenza (RII), North-Western Branch, Russian Academy of Medical Sciences, and sent from resting bases (the regional centers of the Russian Inspectorate for the Protection of Consumer Rights and Human Welfare, which collaborate with the RII). Although the trends in the substitution of representative strains generally coincide with the world patterns, the authors revealed some specific features of the antigenic drift of influenza viruses in the Russian Federation and regional varieties. Data on some biological properties and those of the antigenic analysis of the first pandemic influenza A(H1NI)v strains isolated at the RII from Saint Petersburg patients in July-August 2009 are also given in the paper.

The paper gives the results of sequence analysis of 150 positive samples in real-time RT-PCR, including 47 autopsy materials from patients (including 10 pregnant women), who died from fatal pneumonia mainly in November-December 2009, in whom the lifetime etiological diagnosis had not been made and hence no early etiotropic therapy performed. 70% of the primary materials from the deceased patients were found to have pandemic influenza A(H1N1) v mutants in the lung tissue with D222G (15%), D222N (15%), D222E (2%) substitutions, as well as a mixture of mutants (38%). Nasopharyngeal lavages from 3 Chukotka deceased patients exhibited only consensus (nonmutant) D222 virus variants; there was a mixture of consensus and mutant virus variants in the trachea and a mixture of mutant ones in the lung. Preliminary data from the study of the interaction of the hemagglutinin of two strains having D222G and D222N mutations with 9 oligosaccharides imitating the variants of cell receptors for influenza A virus suggest that there is a double receptor specificity for alpha2'-3' and alpha2'-6'-sialosides with a preponderance of alpha2'-3'-specificity. Further spread of the mutants that have acquired a high virulence and preserved their capacity for the respiratory route of human infection may lead to the situation similar to that seen in the 1918-1919 pandemic. Another scenario for evolution of the virus is to preserve its receptor specificity for alpha2'-3'-sialosides and high virulence with losses of alpha2'-6' specificity and capacity for aerosol transmission, by damping the pandemic.

The paper analyzes the amino acid sequence of the receptor-binding site of hemagglutinin (HA) in the variants of pandemic influenza A/H1N1 swl from 18 patients with moderate (n=1) and fatal (n=17) forms of the disease in 2009. Nine samples contained asparaginic acid at position 222 of HA1 (D). This site exhibited mutations in 9 samples: D222G (n=3), D222N (n=3), and D222G/D222N (n=3). In one patient with the moderate form of the disease, D222G mutation was revealed after the second passage in the developing chick embryos; this mutation was not found in the primary sample from the patient. The findings suggest the mutant variants of the virus start to circulate among the population, which requires, firstly, continuation of molecular virological monitoring of the pandemic situation and, secondly, further study of the impact of amino acid substitutions at the receptor-binding site of HA1 on the increased virulence of influenza A virus.

The paper presents the results of the investigations of the development of a influenza A(H1N1)v pandemic, conducted by the D. I. Ivanovsky Research Institute of Virology, Russian Academy of Medical Sciences, and collaborating laboratories in the European part of Russia, in the Urals, Siberia, and in the Far East. In the prepandemic period (April 27 - June 11, 2009) its first diagnosis was established on May 21, 2009; the first strain was isolated on May 24, 2009; the data on complete genome sequencing were sent to the GenBank; the sensitivity of the strain to commercial antiviral commercial agents was studied. In the early pandemic period (June 11 - August 15), 73 patients who had come from 14 countries of Europe, America, and Asia were identified; 19 virus strains (partially or completely sequenced) were isolated. The pandemic period (August 15 - December 1) was marked by absolute dominance of pandemic influenza virus virtually in the absence of seasonal influenza; the first death caused by pandemic influenza was detected in late August; 3053 subjects were infected with the pandemic strain, as shown by polymerase chain reaction diagnosis; 202 strains were identified.

The paper presents data on the comparative analysis of nucleotide sequences of a S3 gene fragment of 67 chicken reovirus (CRV) isolates from the abnormal biopsy specimens tested in 1999 to 2007. These CRV isolates were ascertained to differ from vaccine strains in the nucleotide sequence of the S3 gene. The approximate substitution rates for the S3 gene were established to range from 2.0 x 10(-3) to 6.0 x 10(-3) nucleotide substitutions per year.

The paper presents the data of an investigation of the polymorphism of the pol gene encoding HIV-1 integrase in a HIV subtype G infected population formed during the 1989 HIV-infection outbreak. The investigators analyzed 41 samples of the viruses obtained in 2005-2007. Polymorphism at codons associated with integrase resistance to chemicals was observed in 11 virus variants. The circulation of mutation viruses that potentially promote the formation of resistance to the integrase inhibitors raltegravir and elvitegravir has been established in untreated patients.

The paper presents the results of studying the spectrum of influenza A and B viruses to rimantadine, arbidol, and oseltamivir and describes the methods used for these purposes for epidemiological surveillance. Different sensitivities to rimantadine were found among influenza A viruses. During the 2007-2008 season, the vast majority of influenza A(H3N2) virus strains were resistant to rimantadine (77%) while all influenza A(H1N1) virus strains preserved their resistance to this drug. The fact that the epidemic influenza A(H1N1) virus strains that carry the mutation responsible for resistance to the neuraminidase inhibitor oseltamivir (Tamiflu) circulated in the Russian Federation was first established. At the same time all the study influenza A(H1N1) virus strains preserved their susceptibility to rimantadine. The sensitivity of the epidemic strains to arbidol has been confirmed.

The paper presents the results of genotyping and phylogenetic analysis of three noncytopathogenic isolates of bovine viral diarrhea virus from the mucosae of the cattle with different clinical presentations of the disease. On the basis of the phylogenetic analysis of high-conserved and variable virus genome regions (5'-UTR, N(pro), and E2), the authors referred two isolates to as genotype 1, subgenotypes 1b and 1d, and the third isolate to as genotype 2. This is the first communication about the isolation of genotype 2 virus in Russia.

The paper presents the data of a comparative analysis of various bioinformation methods for evaluating the tropism of HIV-1 subtype A that is typical of Russia. The prevalence of CXCR4- and CCR5-tropic viruses among the variants prevailing in Russia was studied using the B-PSSM (sinsi) prediction method. No X4-tropic variants were found among 124 samples of HIV-1 isolated from the Russian patients not receiving antiretrovirus therapy.

The paper presents the results of classifying 20 Russian isolates of serotype 1 Marek's disease viruses (MDV) by the adapted "best fit" method (ADOL, USA). The native SPF-chickens of the Shchelkovo line have enough susceptibility for pathotyping of MDV. The Russian isolates were classified by the pathotype in comparison with the reference strains of varying virulence; 8 of them belonged to the vv+ pathotype, 11 to the vv pathotype, and 1 to the v pathotype.

The paper presents the results of interpreting the epizootic outbreak etiologically associated with high-virulent influenza virus A/H5N1 among domestic and wild birds in the Zernogradsky and Tselinsky districts of the Rostov Region. Epizooty was characterized by a high infection rate in the synanthropic birds of a ground-based complex. RT-PCT revealed influenza virus A/H5 in 60% of pigeons and crows and in around 20% of starlings, and in 10% of tree sparrows. Fifteen viral strains from chickens (Gallus gallus domesticus), Indian ducks (Cairina moschata), rooks (Corvus frugilegus), rock pigeons (Columba livia), tree sparrows (Passer montanus), common starlings (Sturnus vulgaris), and great white herons (Egretta alba) were isolated and deposited in the State Collection of Viruses of the Russian Federation. Full-sized genomes of 5 strains were sequenced and deposited in the international database GenBank. The isolated strains belong to the Quinhai-Siberian (2.2) genotype, an Iranian-Northern Caucasian subgroup, they are phylogenetically closest to the strain A/chicken/Moscow/2/2007 (inducing epizooty among poultry in the near-Moscow Region in February 2007) and have 13 unique amino acid replacements as the consensus of the Quinhai-Siberian genotypes in the proteins PB2, PA, HA, NP, NA, and M2, by preserving thereby 4 unique replacements first describes for the strain A/chicken/Moscow/2/2007. The findings are indicative of a different mechanism that is responsible for bringing the virus into the northeastern part of the Azov Sea area in September 2007 (during the fall migration of wild birds) and in December 2007 in the south-western Rostov Region where a human factor cannot be excluded. Mass infection of synanthropic birds endangers the further spread of epizooty, including that in the central regions of the Russian Federation in spring after near migrants return after wintering.

The paper presents the results of the 2003 and 2006 environmental virological monitoring surveys on the Malyi Zhemchuzhnyi Island where a large breeding colony of sea gull (Laridae) is located. In the past several years, expansion of cormorants (Phalacrocorax carbo) has enhanced the intensity of populational interactions. The investigators isolated 13 strains of influenza A virus (Orthomyxoviridae, Influenza A virus) subtype H13N1 (from sea gulls (n = 4), cormorants (n = 9) 1 strain of Dhori virus (Orthomyxoviridae, Thogotovirus) from a cormorantwith clinical symptoms of the disease, 3 strains of Newcastle disease virus (Paramyxoviridae, Avulavirus) from cormorants. RT-PCR revealed influenza A virus subtype H5 in 3.1% of the cloacal lavages from cormorants. Neutralization test indicated that sera from cormorants contained specific antibodies against West Nile (Flaviviridae, Flavivirus) (15.0%), Sindbis (Togaviridae, Alphavirus) (5.0%), Dhori (10.0%), and Tahini (Bunyaviridae, Orthobunyavirus) (5.0%); sera from herring gulls had antibodies against Dhori virus (16.7%); there were no specific antibodies to Inco (Bunyaviridae, Orthobunyavirus) and mountain hare (Lepus timidus) (Bunyaviridae, Orthobunyavirus) virus.

Among agricultural birds in the near-Moscow Region (February 2007), local epizootics caused by the highly pathogenic avian influenza A/H5N1 virus seem to be of unintended manual origin. Such a situation may be considered to be model when the source of inoculation is elucidated in cases of potentially possible acts of bioterrorism. Molecular genetic analysis of isolated A/chicken/Moscow/2/2007 strain established its genetic similarity with the highly pathogenic strains detected in the Black-and-Caspian Sea region in 2006. At the same time, comparison of nucleotide sequences of the strain A/chicken/Moscow/2/2007 with the strains of Qinghai-Siberian genotype (CSG) for which the sequences of full-sized genomes are known in the international databases revealed a significant distinction of the near-Moscow strain from the earlier known analogues. The uniqueness of the primary structure of the PB1 gene is shown. The paper discusses the functional value of amino acid substitutions in the proteins of the strain A/chicken/Moscow/2/2007 and in other variants of CSG of the subtype H5N1.

The evolution of tick-borne encephalitis (TBE) is marked by the expanded nosological area, the transformation of landscapes, the formation of anthropurgic foci, the change of environmental systems, the increase of mortality rate mainly among urban dwellers, as well as pathomorphism. The evolution of natural TBE virus (TBEV) populations was studied in Eastern and Western Siberia, Middle Urals, and the European part of the nosological area. The paper first describes the types of evolutionary transformations of viral populations under the conditions of a varying environmental and epidemiological situation. These include: 1) the change of TBEV subtypes over 50-60 years; substitution of the Far-Eastern subtype for its Siberian subtype (the Sverdlovsk and Kemerovo regions); 2) the steady-state circulation of one Siberian subtype with mutanttypes being accumulated (the Vologda region); 3) co-existence of the Far-Eastern and Siberian subtypes with the common vector Ixodes persulcatus (the Yaroslavl and Irkutsk regions, etc.); 4) original mixed TBEV strains including the gene sites of proteins E and NSI of two subtypes. There is new evidence that the Siberian subtype is able to induce focal TBE forms, leading to death.

Influenza viruses are spread worldwide and cause the disease in birds and mammals, including human beings. Moreover, birds are the natural reservoir of influenza A viruses. Early detection of newly emerging influenza viruses requires permanent monitoring. Traditional viral shedding methods using cell cultures and chicken embryos are time-consuming and laborious analysis when a large number of samples are examined. The paper describes the use of polymerase chain reaction-based test systems to detect influenza A virus and to differentiate its two subtypes: H5 and H7. The developed test systems were evaluated on 19 reference influenza A virus strains. Thereafter, more than 1500 samples from wild and domestic birds, collected in the Russian Federation in 2004-2006, were studied. The data of these test systems were compared with the techniques of viral shedding in the cell cultures and chicken embryos.

The paper presents data of a study of the structure of reverse transcriptase gene in the population infected with HIV subtype G formed during the 1989 HIV infection outbreak in the North-Caucasian region. The authors analyzed 3 samples obtained in 1993-1994 and 17 samples taken in 2000-2001. The phylogenetic analysis indicated that polymerase of the test virus variants belonged to HIV-1 subtype G. The mutations occurring with azidothymidine therapy did not differ from those in subtype B. Analysis of the mutations of resistance to other nucleoside and non-nucleoside reverse transcriptase inhibitors did not show great differences from subtype B either.

The paper describes a case of contamination of sewage samples by a wild poliovirus type 1 strain (Mahoney) in one of the virological laboratories of the Russian Federation. It discusses the possible sources and the mechanism of contamination, as well as the problems in the implementation of the program for safe laboratory containments of wild-type polioviruses.

The paper analyzes the results of isolation of Newcastle disease virus (NDV) strains from 336 swaps of 31 wild bird species collected in the 2001 summer in the Volga estuary (Astrakhan Region). Twenty-seven NDV strains were isolated from little terns (Sterna albifrons) (n=11; infection rate, 24.4%), great cormorants (Phalacrocorax carbo) (n=6; 11.1%), coots (Fulica atra) (n=8; 6.5%), sandwich terns (Sterna sandvicensis) (n=1; 100%), and common redshanks (Tringa totanus) (n=1; 50.0%). Four strains were sequenced by the 374 n. a. residue fragment from the beginning of the F gene, one of them was by the full F gene, and another (Stemal/Astrakhan/2755/2001) was by the full genome. Nucleotide sequences have allowed the authors to classify corresponding NDV strains as 5b genotype and the analysis of the amino acid sequence of the F-protein cleavage site has shown them to belong to a non-pathogenic group.

Molecular virological studies of the field material collected in the epicenter of epizooty with high mortality among mute swans (Cygnus olor) in the area of the lower estuary of the Volga River (November 2005) could establish the etiological role of highly pathogenic influenza A (HPAI) virus of the subtype H5N1. Ten HPAI/H5N1 strains deposited at the State Collection of Viruses of the Russian Federation with the priority dated December 1, 2005 were isolated from the cloacal/tracheal swabs and viscera of sick and freshly died mute swans. Complete nucleotide sequences of all fragments of the genome of 6 strains have been deposited in the Gene Bank. The paper discusses the molecular genetic characteristics of isolated strains.

The paper presents the results of epidemiological surveys for HIV infection in 15 administrative areas of the Volga Federal Okrug of Russia, starting in 1988. Two periods of an epidemic process in the okrug are comparatively characterized. Different levels of HIV prevalence in the Volga regions are shown. Some conditions contributing to a higher prevalence of HIV infection in some areas of the okrug are outlined.

The paper presents the results of investigations of hepatitis E (HE), which have been made at the Department of Viral Hepatitides, M. P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences. M. S. Balayan's discovery of hepatitis E virus permitted etiological interpretation of the cases of so-called non-A, non-B hepatitis with its fecal and oral transmission. The detection of antibodies to HE virus among different groups of the population of Russia (i.e. a hepatitis E nonendemic region of the world) suggests that they are frequently detected in the absence of disease notification. The fact that viral HE RNA has been detected in the pigs and wild boars inhabiting in the country is evidence in favor of an assumption that the virus is spread among these animals. The hypothesis for HE as a zoonosis is discussed in the paper.

Summarized in the paper are study results of human herpesvirus type 8 (HHV-8) and of its association with Kaposi's sarcoma (KS). The data obtained denotes that the share of individuals producing the antibodies to HHV-8 in a majority of studied patients was low and ranged form 0 to 5.5%, which is indicative of a low degree of the virus spread in population. At the same time, a high share of persons with antibodies to HHV-8 was detected among HIV-infected homosexuals (71.4%), kidney recipients (26.0%) and among AIDS-KS patients (78.6%). It was also unexpectedly high among patients with T- and B-cell lymphomas (50%), encephalopathy (27.3%) and with stomach cancer (41.8%): the appropriate parameters were 7-12-fold higher versus healthy subjects. The HHV-8 markers, i.e. virus specific antibodies and/or nucleotide sequences of the virus, were detected in blood serum and ejaculate of a significant number of patients with different pathologies of the prostate. Such detection of viral markers in the above categories of patients is suggestive of that sexual contacts with such patients are decisive for the HHV-8 spread in population.

Measles, rubella and epidemic parotitis are classified as controllable infections with vaccination of children being the key method of preventing them. Live mono-vaccines and combined vaccines against measles and epidemic parotitis have been developed and successfully used in our country; research work on creating preparations against rubella has been underway. The vaccine-based prevention of the above viral infections is shown to be a most active, safe, effective and cost-saving method preventing them. There is also described in the paper an analysis of the morbidity rate due to measles, rubella and epidemic parotitis in the territory of the Russian Federation and elucidated the resolved and yet unsettled issues related with the vaccine-based prevention of the above widespread and highly contagious infections of today.

The research results on ecology and evolution of influenza A viruses, which has been conducted by the Center of Ecology and Evolution of influenza Viruses of Ivanovsky's Institute of Virology, Russian Academy of Medical Sciences, for more than 30 years, are summarized in the paper. A gene pool of influenza A viruses circulating in Russia's territory was defined. Foci of influenza A viruses were detected in natural biocenosis. Issues conditioned by the population interrelations of influenza viruses, i.e. between the populations of wild and home animals and the populations of people, are also under discussion.

Described in the paper are study results of some immunobiological properties of 5 field isolates of the porcine reproductive and respiratory syndrome virus (PRRSV), obtained in Russia and Byelorussia in 1998-2001. According to the research work, the PRRSV isolates with different immunobiological properties have been circulating in the territories of Russia and Byelorussia. Three of the 4 examined virus isolates were found to be pathogenic and 1 avirulent to pigs.

A study of distributions of different genetic variations (subtypes) of hepatitis C virus (HCV), circulating in the territories of Yekaterinburg and Chelyabinsk among infected population categories of different social statuses and age, is reported in the paper. The predominance of 1b subtype was shown in the HCV-infected patients at the hemodialysis center (HDC) and at the pediatric oncohematology center (OHC), 83.3% and 84.6% respectively. The summarized results of examinations of patients conducted at HCV-infection departments (97 persons) did not reveal any essential differences between the data, obtained for Moscow and Saint-Petersburg, concerning the distributions of HCV subtypes. However, according to an analysis made in cities of the Urals region, the prevalence of 1b subtype in Chelyabinsk was 2-fold higher than that of 3a subtype, whereas in Yekaterinburg there was an equal ratio (1:1) between the above subtypes. Besides, unequal distributions of HCV subtypes were registered in different age groups. 3a subtype was found to be predominant in patients aged 15 to 27, and prevalence of 1b subtype persisted in persons aged below 15 and above 27. The conclusion is that the redistributed occurrence rates of separate HCV subtypes, with their spectrum in mentioned territories being preserved, is associated with a growing number of young drug-addicts who are more often get infected with 3a subtype.

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.

Data on the circulation of a new genetic variant of Seol virus, which was designated as "Vladivostok" (the name of the place where it was isolated)--VDV, were obtained, by using the antigenic and genetic analysis of hantavirus strains isolated from patients with hemorrhagic fever with renal syndrome (HFRS) and from brown rats, and described in the present paper. A complete identity of nucleotide sequences of the M-segment fragment of isolates obtained from HFRS patients and of those obtained from rats was demonstrated, which confirms the key role of brown rat as a source of infection.

The paper briefly presents clinical, epidemiological, virological and serological data on cases of Crimean-Congo hemorrhagic fever (CCHF) in Astrakhan Province. The results indicate annual infection of the regions population with CCHF virus, the main mode of transmission being vector-borne. The advantages of the fluorescence antibody technique and enzyme immunoassay-for diagnosis of the disease were demonstrated.

The paper presents the results of 3-year observations of the status of herd immunity to poliomyelitis in 7 towns of the Moscow region. In individual years antibody for poliomyelitis virus of 3 types was found in 63-74% of the examined children and from 2.7 to 7.5% of children were triple-negative. Insufficient levels of herd immunity to poliovirus types I and III were found. Some factors are analysed which could have some influence on the decline of herd immunity.

In accordance with the Soviet-American collaboration program on influenza and ARD, cooperative field studies were undertaken in 1975 in the USSR in order to test the field and laboratory methods for studies on influenza virus ecology. In the Rostov region of the USSR, virological and serological examinations of 321 birds of 25 species were carried out. Virological tests were performed with 678 biological specimens and in various serological tests 308 blood serum specimesn from wild birds were examined. Examinations of specimens of washings and organs of birds revealed no hemagglutinating agents. The paper presents the results of studies of avian blood serum specimens in the HI test, neuraminidase activity inhibition test and the immunodiffusion test.