Genetic Diversity and Possible Origins of the Hepatitis B Virus in Siberian Natives.

A total of 381 hepatitis B virus (HBV) DNA sequences collected from nine groups of Siberian native populations were phylogenetically analyzed along with 179 HBV strains sampled in different urban populations of former western USSR republics and 50 strains from Central Asian republics and Mongolia. Different HBV subgenotypes predominated in various native Siberian populations. Subgenotype D1 was dominant in Altaian Kazakhs (100%), Tuvans (100%), and Teleuts (100%) of southern Siberia as well as in Dolgans and Nganasans (69%), who inhabit the polar Taimyr Peninsula. D2 was the most prevalent subgenotype in the combined group of Nenets, Komi, and Khants of the northern Yamalo-Nenets Autonomous Region (71%) and in Yakuts (36%) from northeastern Siberia. D3 was the main subgenotype in South Altaians (76%) and Buryats (40%) of southeastern Siberia, and in Chukchi (51%) of the Russian Far East. Subgenotype C2 was found in Taimyr (19%) and Chukchi (27%), while subgenotype A2 was common in Yakuts (33%). In contrast, D2 was dominant (56%) in urban populations of the former western USSR, and D1 (62%) in Central Asian republics and Mongolia. Statistical analysis demonstrated that the studied groups are epidemiologically isolated from each other and might have contracted HBV from different sources during the settlement of Siberia.

Hepatitis A outbreak linked to imported frozen strawberries by sequencing, Sweden and Austria, June to September 2018.

Between June-September 2018, 20 hepatitis A cases were notified in six counties in Sweden. Combined epidemiological and microbiological investigations identified imported frozen strawberries produced in Poland as the source of the outbreak. Sequence analysis confirmed the outbreak strain IB in the strawberries with 100 % identity and the respective batch was withdrawn. Sharing the sequence information internationally led to the identification of 14 additional cases in Austria, linked to strawberries from the same producer.

Prevalence of Antibodies Against Hepatitis E Virus in Veterinarians in Estonia.

In this cross-sectional study, we investigated veterinarians in Estonia for evidence of exposure to hepatitis E virus (HEV). In 2012, we collected sera from 158 persons attending a veterinary conference, of whom 156 completed a questionnaire covering their background information. Altogether 115 persons reported they had obtained a veterinary degree and were included in this study. The sera were tested for presence of antibodies against HEV using a commercial enzyme linked immunosorbent assay and a commercial immunoblot assay in series. A sample was considered antibody-positive if it tested positive with both tests. Antibody-positive samples were further examined for the presence of HEV RNA. Three (2.6%) of the 115 veterinarians tested positive for immunoglobulin G antibodies against HEV, whereas no immunoglobulin M antibodies against the virus were detected. The antibody-positive veterinarians were small animal practitioners. Pigs comprised no or small part of their working time or patients. No HEV RNA was detected in the antibody-positive samples. The prevalence of antibodies against HEV in veterinarians in Estonia was lower than what has been observed in veterinarians in other countries.

Amino Acid Polymorphisms Within the Entire HCV NS5A Region in Estonian Chronic HCV 1b Patients With Different Treatment Response.

BACKGROUND: A substantial proportion of hepatitis C virus (HCV)-1b infected patients do not response to pegylated interferon-α plus ribavirin (PegIFNα/RBV) combination therapy that was partially associated with mutations in the non-structural 5A (NS5A) protein. OBJECTIVES: Analysis of NS5A polymorphisms in HCV genotype 1b pre-treatment serum samples from Estonian patients and their effect on the treatment response. PATIENTS AND METHODS: Twenty-nine complete NS5A sequences obtained from patients with chronic HCV-1b infection who had received combined therapy with PegIFNα-2a/RBV were analyzed and compared with the prototype strain HCV-J. Twelve patients achieved a sustained virological response (SVR), 15 were non-SVR and 2 patients stopped treatment because of side effects. RESULTS: No significant difference in total number of amino acid mutations was observed between isolates from SVR and non-SVR patients in any known regions of the NS5A protein. However, specific amino acid substitutions at positions 1989 and 2283 correlated significantly with SVR, mutations at positions 1979, 2107, 2171 and 2382 were associated with non-response to treatment and amino acid substitution at position 2319 was observed in relapsers. At phylogenetic analysis, NS5A nucleotide sequences have been subdivided into four groups characterized by the different treatment response. Twenty-four novel nucleotide polymorphisms and 11 novel amino acid polymorphisms were identified based on the phylogenetic tree topology. CONCLUSIONS: Specific amino acid substitutions correlating with the treatment response were found. Polymorphisms revealed by phylogenetic analysis may define the signature patterns for treatment susceptible and treatment resistant strains prevalent in Estonia.

Efficacy of peginterferon alpha-2A and ribavirin combination therapy in treatment-naive Estonian patients with chronic hepatitis C.

AIM: The aim of the study was to assess the efficacy of pegylated interferon (Peg-IFN) alpha-2a and ribavirin (RBV) combination therapy in treatment-naive patients with chronic hepatitis C in Estonia. METHODS: Out of 121 outpatients with chronic hepatitis C (73 males, 48 females, aged 19-63) enrolled in the study, 76 were infected with HCV genotype 1b and 45 with genotype 3a. At baseline, the viral load in 75.2% of patients was higher than 600,000 IU/mL. Histologically, 88.4% of patients had fibrosis score F0-2. Patients received 180 microg of Peg-IFN alpha-2a weekly plus daily ribavirin 1,000 or 1,200 mg, depending on body weight, in HCV genotype 1b, or 800 mg/day in genotype 3a infection. RESULTS: The overall sustained virologic response (SVR) rate in our study was 60.3%, being statistically lower for patients with HCV genotype 1b as compared to patients with genotype 3a (46.1% vs. 84.4%, p < 0.05). The non-response and relapse rates were significantly higher in patients infected with HCV genotype 1b compared with patients infected with genotype 3a (19.7% vs. 2.2%, p = 0.01; and 17.1% vs. 4.4%, p = 0.04; respectively). The SVR rate was higher in patients younger than 40 years compared with older patients (76.4% vs. 47.0%, p < 0.01), regardless of the genotype. Thirteen patients infected with HCV genotype 1b required dose reduction of PegIFN and/or RBV because of adverse side effects. Nine of them achieved SVR. CONCLUSION: HCV genotype and age younger than 40 years predetermined SVR rate in treatment-naive Estonian patients with chronic hepatitis C treated with Peg-IFN alpha-2a plus ribavirin.

The trends and risk factors for hepatitis B occurrence in Estonia.

Hepatitis B virus (HBV) infection is prevalent worldwide and is a significant cause of morbidity and mortality. This article describes the trend in HBV occurrence in Estonia from 1990 to 2005 in Estonia, with the aim of highlighting key determinants in transmission dynamics, risk groups, and possible implications for prevention and control. A marked increase in reported numbers of new HBV cases occurred in mid 1990s (reaching 39 per 100,000 population) and decline thereafter. We present data on HBV prevalence from different population groups (persons with verified sexually transmitted infection, prisoners, medical personnel, blood donors and injection drug users). Special vaccination programmes introduced in Estonia have been successful in the prevention of HBV, however, we suggest that the main risk groups such as injection drug users (IDUs), men having sex with men (MSM) and HIV infected persons should be actively encompassed into HBV vaccination programme.

D2: major subgenotype of hepatitis B virus in Russia and the Baltic region.

Complete or almost complete hepatitis B virus (HBV) genomes were sequenced for 13 genotype A and 42 genotype D strains from the former USSR. The strains were classifiable within subgenotypes A2, D1, D2 and D3. Comparison of the deduced gene products for the four ORFs of 89 genotype D strains revealed 27 subgenotype-specific residues, and a region spanning residues 58-128 in the spacer region of the P gene could be used to distinguish between D1 and D4. This enabled the allocation to subgenotype of strains with partially sequenced genomes. D2 was dominating, while D3 was found in low frequency in the whole region. D1 was most prevalent in the Middle Asian Republics. Mean inter-subgenotype divergences between D1 and D2, D1 and D3 and D2 and D3 were 2.7, 3.4 and 3.4 %, respectively. The intra-subgenotype divergence was 0.4, 1.1, 1.0 and 1.8 % for A2, D1, D2 and D3, respectively. All D1 and D3 strains encoded subtype ayw2, whereas most D2 strains encoded ayw3. Two D2 strains encoded ayw4. Strains with identical S genes were closely related at the level of complete genomes and formed geographically specific clades with low intraclade divergences, possibly indicating past iatrogenic spread. It is not clear whether the finding of four subgenotypes in the area corresponds to separate introductions of the virus or to previous population migrations into the area. An earlier introduction of D3 compared with D2 was supported by its higher intra-subgenotype divergence, while the lower divergence within D1 is probably due to a more recent emergence.

Genetic characterization of hepatitis C virus strains in Estonia: fluctuations in the predominating subtype with time.

During the last decade, there has been a dramatic increase in intravenous drug use in young adults in Estonia with an increased incidence of both hepatitis B and C as a consequence. Since genetic data are limited regarding hepatitis C virus (HCV) strains in Estonia, the aim of the study was to characterize HCV strains in different risk groups to determine their relatedness to strains from other geographical regions. Three hundred fifty-three anti-HCV positive sera collected during 1994-2004 from hospitalized patients, blood donors and health care workers were used as source of HCV RNA. Two hundred nine (59%) of the sera were positive for HCV RNA by PCR directed to the 5'-UTR region. For 174 strains the HCV subtype was determined by analyses of the NS5B and/or the 5'UTR-core regions. 1b (71%) was the most common subtype followed by 3a (24%), 2c (2%), 1a (1%), and 2a (1%). The 1b and 3a strains were similar to strains from other regions of the former USSR. Within genotype 1b there were several HCV lineages. However, for 3a there seemed to be two separate introductions into Estonia. There was a relative shift from subtype 1b to 3a in 1999-2000 with a further replacement of 3a with 1b in intravenous drug users in 2001 and onwards (P < 0.05). However, both subtypes were found to co-circulate in the community independent of risk factors. One patient was infected with the 2k/1b recombinant presumed to originate from St. Petersburg being the first isolate of this recombinant recovered outside Russia.

Hepatitis B virus genotype D strains from Estonia share sequence similarity with strains from Siberia and may specify ayw4.

The genotypes and subtypes of 205 HBV isolates collected during 1989-2002 in Estonia and 14 other regions of the former USSR were determined by sequencing and phylogenetic analysis of the S gene. The in Europe prevailing genotypes, A and D, were also circulating in the whole territory of the former USSR including Estonia and accounted for 18.5 and 81% of the strains, respectively. All genotype A strains specified adw2, and a single genotype C strain specified adrq+. Most genotype D strains specified ayw3 and ayw2, although, three strains from Estonia and Siberia specified ayw4. Due to unique substitutions, Ser122 and Ala127, four strains could not be classified according to the subtype. One strain specifying ayw3 encoded Leu143 and Ala145 and was possibly an immune "escape" mutant. At phylogenetic analysis 93% of the Estonian genotype D strains belonged to a cluster specifying mainly ayw3 and were more similar to isolates from Siberia and the Far-East of Russia than to isolates originating from Central Russia which belonged to another cluster of strains specifying mainly ayw2. This pattern might be explained by part of the Estonian population, has roots east of European Russia, based on linguistic evidence. Eight dominant HBV strains represented by identical S gene sequences were identified, one within genotype A and seven within genotype D, three of which included isolates from Estonia and Siberia. Some of these strains were collected over a period of at least 13 years indicating there are genetically stable variants of HBV that remain conserved over decades.

Sequential changes in hepatitis A virus genotype distribution in Estonia during 1994 to 2001.

Hepatitis A virus (HAV) isolates from a large outbreak and from non-outbreak cases in Estonia were characterized by sequencing the aminoterminal VP1 region. From January 1998 to December 1999, a total of 1084 cases of hepatitis A were reported to the Harjumaa-Tallinn and Ida-Virumaa Health Protection Services in Estonia. The attack rate was highest among males aged 15-29. Initial cases were noted to be associated with injecting drug use. IgM anti-HAV positive sera were available from 107 hospitalized outbreak cases and from 68 patients sampled during 1994 to 2001. HAV RNA was detected in 42% of sera from 1994-1996 and in 88% of sera from 1998-2001. It was possible to obtain HAV sequences from 83 outbreak and 29 background cases. The outbreak strain was represented by five different sequences, all belonging to subtype IIIA. During the outbreak, this IIIA strain also spread into the general population. All available non-outbreak isolates from 1994 to 2001 but one belonged to genotype IA and formed distinct clusters as compared to isolates from other parts of the world. One subtype IIIA isolate from 1995 was unrelated to the outbreak strain. Subtype IA had been dominating in Estonia during 1994-2001, but the outbreak strain from 1998 to 1999 was IIIA. This subtype was encountered previously in addicts in Sweden during the 1980s and in Norway at the end of the 1990s. This study supports the use of limited sequencing within the aminoterminal VP1 region for studying the molecular epidemiology of hepatitis A.