TT virus (TTV) is a common virus and consists of many genotypes and variants. In addition, there exists a virus which both differs greatly from and retains a considerable resemblance to TTV, such as the TTV-like mini virus (TLMV) as we reported previously. Here we report the near full length genomic sequences of 4 isolates of a new variant of TTV (designated YONBAN) along with the full length sequences of 2 isolates of the TTV-SANBAN lineage and 7 isolates of the TLMV species derived from human sera. The TTV-YONBAN sequences showed only about 50% identity at the nucleotide level to those of the prototype TTV (TA278) and to SANBAN, and even less to TLMV. Moreover, the ORF1 of YONBAN lacked the ATG initiation codon which is shared by all the TTV and TLMV isolates so far identified in humans; instead, YONBAN had a Kozak’s rule-compatible ACG codon as the candidate initiation site for the ORF1 translation. Nevertheless, the overall genetic structure and the conserved amino acid motifs within the ORF1 and the ORF2 were well shared among the prototype TTV strains, the SANBAN and YONBAN variants, and TLMV. The most conserved nucleotide sequence was found in the noncoding region just upstream from the ORF2, allowing construction of a phylogenetic tree which implied that the TTV genotypes and variants, the TLMV, and chicken anemia virus could be coclassified under a superfamily for which we proposed the name of ‘Paracircoviridae’ in our previous report.

We tested hepatitis C virus (HCV) antibody in 4216 sera collected from healthy people living in European part of Russia (including Northern, North-Western, Central, Central-Blacksoil, Volga-Vyatka, Volga, and North-Caucasian regions), non-European part of Russia (the Urals, East-Siberia, and the Far-East regions) and Mongolia. Prevalence of HCV antibody varied significantly by regions, ranging from 0.7% in Central region of European part of Russia to 10.7% in Mongolia. Genotyping of HCV (into 1a, 1b, 2a, 2b, and 3a) was performed on 469 sera from blood donors and patients (in Russia, Moldova, Turkmenistan, and Mongolia) who were positive for both HCV antibody and RNA. Genotype 1b was the most dominant genotype irrespective of regions (68.9%), with the highest rate in Moldova (96%). HCV unclassifiable into genotypes 1a-to-3a was found in 28 (6.0%) samples: particularly 4 of 10 samples from Lipetzk were untypable. Overall, HCV genotypes in European part of Russia were more similar to those in European countries, while those in Eastern part of Russia more similar to China or Japan. Genotype distribution was not associated with the clinical expression of HCV disease: acute hepatitis, chronic hepatitis or liver cirrhosis.

Progress in studying pathogenesis and increasing the reliability of hepatitis C diagnosis can be achieved by analysis of different forms of virus particles circulating in blood of both patients and infected persons. Detection of hepatitis C virus (HCV) proteins faces two basic difficulties: low concentration of HCV proteins, and their blocking by antibodies. The aim of this work was to develop a method for the detection of nucleocapsid (core) protein in the plasma of HCV-infected persons using monoclonal antibodies (MABs). Twenty-seven anti-HCV-positive donor plasmas were studied of which 21 contained HCV RNA and 6 were negative. The plasmas were centrifuged for 3 hr at 143,000 g and the antigenic activity of core-protein was studied in the pellets by EIA using four MABs able to recognize four nonoverlapping determinants, two at N-terminus and two at C-terminus of recombinant core (1-150 aa). The determinants detected were present in the natural core protein of at least two genotypes (1b and 3a). Maximal efficiency of recombinant protein detection was achieved with 2 MABs, whereas a combination of 4 MABs was necessary for optimal detection of natural core protein. This is indicative of different conformational structures of natural protein and its gene-engineered analog. The sensitivity of core detection by monoclonal sandwich assay was 1 ng/ml in the pellet or 5 pg/ml after normalization to the initial plasma volume. To dissociate immune complexes, the pellet was treated with 2.5 M KBr after first treating the pellet with the nonionic detergent Tween 80 to remove the virus lipid envelope. Using this treatment protocol, core protein was found in 19 of 21 RNA positive plasmas.

TT virus (TTV) lacks obvious pathogenicity; almost all of the infected hosts are symptom-free. A possibility remains, however, that certain strains can cause liver disease while most others are non-pathogenic. Genotypes 1 a and 1 b have been proposed to contain such pathogenic strains. To test this possibility, we constructed a PCR system capable of detecting TTV of the 1 a and 1 b genotypes differentially from the other genotypes, and compared the frequencies of these genotypes between patients with liver disease of unknown etiology (n=42) and healthy individuals (n=50). The assay comprised 3 steps: i) PCR to amplify a 3.2-kb fragment using universal primers; ii) 2nd-round PCR, starting from the 3.2-kb amplicon, for a approximately 280-nt fragment by use of genotype 1-specific primers; and iii) digestion of the approximately 280-nt amplicon with MboI and BanI to discriminate between 1 a and 1 b. Eventually, 40 (95%) of the patients and 47 (94%) of the controls were positive for the 3.2-kb amplicon, and the 1 a, 1 b, 1 a+1 b, and non-1 genotypes of TTV were found in 2 (5%) vs 4 (9 percent), 5 (13%) vs 4 (9%), 1 (3%) vs 1 (2%) and 32 (80%) vs 38 (81%) of the 40 patients and 47 controls, respectively: the distribution was almost identical between the two groups. The hypothesis that the genotype 1 of TTV may be more closely associated with liver disease than other genotypes was not supported by this study.

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Introduction. The new reassortant of the swine flu virus A(H1N1)pdm09, which emerged in 2009, overcame the species barrier and caused the 2009-2010 pandemic. One of the key points required for the influenza virus to overcome the species barrier and adapt it to humans is its specific binding to the receptors on the epithelium of the human respiratory tract.Targets and goals. Studying the dynamics of changes in receptor specificity (RS) of the HA1 subunit of the hemagglutinin of the influenza A(H1N1)pdm09 virus strains isolated during the period 2009-2016 on the territory of the Russian Federation, and an analysis of the possible impact of these changes on the incidence rates of the population of the Russian Federation of pandemic influenza in certain epidemic seasons. Material and Methods. Standard methods of collecting clinical materials, isolation of influenza viruses, their typing and genome sequencing were used. For the study of RS of influenza A virus (H1N1)pdm09, the method of solid phase sialosidenzyme analysis was used. Results. It is shown that the change in the parameter W3/6 , which characterizes the degree of a2-3 receptor specificity (a2-3-RS) of the influenza virus A(H1N1)pdm09 over a2-6-RS, coincides with the change in the incidence rates of the Russian Federation’s pandemic flu in separate epidemic seasons. There is a tendency to increase the affinity of the virus A(H1N1)pdm09 to α2-3 analogs of the sialyl-glycan receptors of the human respiratory tract epithelium - α2-3-sialoglycopolymers (α2-3-SGP), and falls to α2-6-SGP, with the virus showing the greatest affinity for sulfated sialoglycopolymers. Discussion. Screening for RS strains of influenza A (H1N1)pdm09 virus isolated on the territory of the Russian Federation in 2009-2016 revealed a decrease in the affinity of viruses for a2-6-sialosides, especially for 6’SL-SGP, which is probably due to the presence of amino acid substitutions in the 222 and 223 positions of RBS HA1 viruses. Previous studies have shown that the presence of such substitutions correlates with an increase in the virulence of the influenza A virus (H1N1)pdm09 [16, 23]. Probably, the pandemic virus has evolved towards the selection of more virulent pneumotropic variants. Conclusion. Monitoring of the receptor specificity of a pandemic influenza virus makes it possible to identify strains with altered RS to the epithelium of the human respiratory tract and an increased ability to transfer from person to person. Change in the period 2009-2016 the W3/6 parameter characterizing the degree of α2-3-RS excess of the influenza A(H1N1)pdm09 virus over α2-6-RS, coincides with the change in the incidence rates of the pandemic influenza population of the Russian Federation in certain epidemic seasons.

Hepatitis C virus (HCV), a single-stranded RNA virus of the family Flaviviridae, has a wide range of genetic heterogeneity: 6-11 genotypes (or 6 clades) have been known and each genotype comprises multiple subtypes. Here we report the entire nucleotide sequence of an HCV isolate from a patient in Moldova with chronic hepatitis (isolate name VAT96). The genetic organization of VAT96 was, from 5' to 3' ends, 5'UTR (341 nt), polyprotein ORF (9099 nt), 3'UTR (38 nt except for the poly-U and poly-pyrimidine stretch), and X-tail (98 nt). Comparison of the polyprotein amino acid sequence of VAT96 with those of known full-genome isolates assigned VAT96 to the genotype 2 (or clade 2), and further phylogenetic analysis based on a 447-nt sequence that covers part of the C and El regions suggested that VAT96 represents a new subtype within the genotype 2, arbitrarily designated "2k" VAT96 was unique in that it possessed a U residue prior to GCC at the 5' end of its genome while all the other full-genome HCV sequences start with GCC or ACC. In addition, the polyprotein ORF of HCV-VAT96, like HCV-BEBE1 of 2c, encoded several additional amino acids in excess, compared to 2a and 2b sequences. Despite these characteristics that may be unique to VAT96, the 98-nt sequence of the X-tail of VAT96 was highly homologous to those of other isolates with different genotypes so far reported.

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