Detection of antibodies to the hepatitis E virus in domestic reindeer (Rangifer tarandus) in the Republic of Sakha (Yakutia).

Introduction: Although domestic pigs and wild boars are the main reservoir of zoonotic hepatitis E virus (HEV) genotypes in temperate countries, the presence of antibodies to HEV (anti-HEV) in the indigenous population of circumpolar territories, i.e. outside the habitat of wild and domestic pigs, indicates the presence of an alternative reservoir of the virus. Reindeer (Rangifer tarandus) may be a potential reservoir for HEV in the polar regions. The purpose of the study was to determine the prevalence of anti-HEV among domestic reindeer in the Republic of Sakha (Yakutia).

Materials and methods: Sera from 497 domestic reindeer from the Oymyakon (n = 425) and Ust-Yansky districts (n = 72) of the Republic of Sakha (Yakutia) were tested for anti-HEV. A commercial ELISA kit DS-ELISA-ANTI-HEV-G (Diagnostic Systems-Stolitsa LLC, Russia) was used for detection of anti-HEV IgG, but a rabbit polyclonal antibody against deer IgG labeled with horseradish peroxidase (KPL, USA) at a dilution of 1 : 100 in phosphate-buffered saline were used instead of the human specific conjugate from the kit.

Results: The average detection rate of anti-HEV in reindeer sera was 15.5% (95% CI: 12.6-19.0%). The detection rate of anti-HEV significantly increased with age, from 3.5% (95% CI: 1.1-9.0%) in calves aged 3-6 months to 25.0% (95% CI: 1.6 -36.5%) in deer aged 2-4 years (p < 0.0001). From this age group, anti-HEV detection rates reached a plateau, not differing significantly between older age groups (p > 0.05). The average anti-HEV detection rate among reindeer 2 years of age and older was 19.0% (95% CI: 15.3-23.4%). There were no statistically significant differences in the frequency of anti-HEV detection between female and male reindeer, both among adult animals and among calves.

Conclusion: The observed anti-HEV detection rates among domestic reindeer in the Republic of Sakha (Yakutia) indicate that infection caused by HEV or an antigenically similar virus is common in these animals. The dynamics of antibody accumulation in the reindeer population indicates that infection apparently occurs during the first two years of life.