[Belgorod region - the territory endemic for hepatitis E.]

INTRODUCTION: Belgorod region is the territory with the highest incidence of hepatitis E in the Russian Federation. OBJECTIVES: The aim of the study was to comprehensively characterize the circulation of hepatitis E virus (HEV) in the Belgorod region, including the study of population immunity to the virus, determining the prevalence of infection among the pig population and analysis of the genetic diversity of HEV from patients and animals. MATERIAL AND METHODS: Serum samples of a conditionally healthy population (n = 2027) of all age groups were tested for anti-HEV IgG and IgM by ELISA with commercial assays. HEV RNA was determined in fecal samples from pigs aged 2-4 months (n = 526), in sewage samples from pig farms (n = 10), as well as in stool samples from patients with hepatitis E (n = 6) using reverse transcription polymerase chain reaction (RT-PCR). Phylogenetic analysis was performed for an amplified 300 nt fragment corresponding to HEV open reading frame 2. RESULTS AND DISCUSSION: The prevalence of anti-HEV IgG in general population averaged 16.4% (95% CI: 14.8-18.1; 332/2027). The proportion of individuals who had both anti-HEV IgM and IgG averaged 2.8% (95% CI: 2.2-3.6; 57/2027). The incidence rate of anti-HEV IgG increased with age, from 2.8% (95% CI: 1.3-5.8) in children aged 1-14 years to 40.1% (95% CI: 34.9-45.6) in people 70 years or older. The detection rate of HEV RNA in pigs was 20% (95% CI: 16.8-23.6; 105/526). HEV RNA was detected in 2 out of 10 sewage samples. The HEV sequences isolated from patients with hepatitis E, pigs, and sewage samples in Belgorod region belonged to the HEV genotype 3, had a 95-100% homology, and formed common clusters on a phylogenetic tree. CONCLUSIONS: The high prevalence of HEV in pigs population has led to the formation of an endemic territory in the Belgorod region, which is the center of pig breeding. Measures aimed at reducing the circulation of HEV among pig population and decontamination of sewage from pig farms are necessary to control HEV infection.

[The duration of preservation of anamnestic antibodies to hepatitis E virus.]

The purpose of the study was to determine the duration of antibody response against hepatitis E virus (anti-HEV). Veterans of the war in Afghanistan who were in this endemic region in the late 1970s and early 1980s were tested for anti-HEV. On average, 20 years after the end of military service in Afghanistan, the rate of seropositivity was 30.0% (95/317), which was significantly higher compared to positivity rates in males who were at military service in the territory of Russia during the same period (3.9%, 8/208). At an average of 29.5 years after the visit to Afghanistan anti-HEV prevalence in veterans dropped to 20.0% (21/105), but still significantly exceeded the seroprevalence in general population (3.8%). Serum samples from elderly individuals (>60 years) without known risk factors of infection were also tested for anti-HEV IgG and IgM (n = 896). Anti-HEV IgG detection rates in the elderly from two regions of Russia exceeded those observed of primary blood donors (18.0-27.8% vs. 4.5-10.0%, p<0.01). The detection of anti-HEV IgM in individuals above 60 years (2.7-6.9%) indicates a current or recent infection. Thus, anti-HEV IgG can persist several decades after the infection. This might account for the wide anti-HEV prevalence among the elderly. At the same time, a significant proportion of individuals exposed to HEV lose detectable anti-HEV IgG within 20-30 years. The detection of anti-HEV IgM among the elderly indicates the viral circulation in older age groups, suggesting the need for testing for hepatitis E markers in elderly patients with liver diseases.

[The standardization of diagnostic of hepatitis E.]

The study was carried out to develop approaches to standardization of laboratory diagnostic of hepatitis E. The three stages of standardization are establishment of analytical sensitivity of molecular test for detection of RNA of virus of hepatitis E; establishment of analytical sensitivity in International Units of enzyme-linked immunosorbent assay testing widely applied in Russia for detection of anti-virus of hepatitis E; And development of national reference material - standard anti-virus of hepatitis E IgG validated relatively to International standard. The results of study permitted to develop tools for standardizing of laboratory diagnostic of hepatitis E and epidemiological control of the given function - molecular test for detecting RNA of virus of hepatitis E with sensitivity within range of 1250250 IU/ml, data concerning analytical sensitivity of commercial enzyme-linked immunosorbent assay testing for detecting anti-virus of hepatitis E (0.25 IU/ml) and national standard of anti-virus of hepatitis E with concentration of 5 IU/ml.

[Prevalence of hepatitis E markers in children].

AIM: Frequency of detection determination for past and current hepatitis E virus (HEV) infection markers in children with immune suppression, as well as children with normal immune status. MATERIALS AND METHODS: The presence of HEV markers (anti-HEV IgG and IgM, HEV RNA) was studied in 609 sera samples of children with neurologic pathologies, 87 samples--from children with immune deficiencies, as well as 3122 samples from conditionally healthy children of 6 regions of Russia. The children were divided into 5 age groups. Anti-HEV IgG and IgM determination was carried out in EIA, HEV RNA--by RT-PCR. RESULTS: The frequency of detection of anamnestic anti-HEV IgG turned out to be significantly higher among immune-compromised. children compared with healthy children (5.7% against 1.4%, p < 0.05). Anti-HEV IgM, that testify to current or recent infection, were also detected significantly more frequently among children with immune-suppression (1.1-1.6%) compared with healthy children (0.25%, p < 0.05). HEV RNA was detected in 1 child with the absence of anti-HEV IgM and IgG. Nucleotide sequence analysis of HEV confirmed membership of this isolate in genotype 3, that is prevalent in non-endemic territories. CONCLUSION: The data obtained have demonstrated, that HEV-infection is prevalent among children in Russia and its course is, probably, asymptomatic in most cases. Immune suppression is a factor of increased risk of infection of children with HEV.