Background and Aims Hepatitis E virus (HEV) variants causing human infection predominantly belong to HEV speciesA(HEV-A). HEV speciesCgenotype 1 (HEV-C1) circulates in rats and is highly divergent from HEV-A. It was previously considered unable to infect humans, but the first case of human HEV-C1 infection was recently discovered in Hong Kong. The aim of this study is to further describe the features of this zoonosis in Hong Kong. Approach and Results We conducted a territory-wide prospective screening study for HEV-C1 infection over a 31-month period. Blood samples from 2,860 patients with abnormal liver function (n = 2,201) or immunosuppressive conditions (n = 659) were screened for HEV-C1 RNA. In addition, 186 captured commensal rats were screened for HEV-C1 RNA. Sequences of human-derived and rat-derived HEV-C1 isolates were compared. Epidemiological and clinical features of HEV-C1 infection were analyzed. HEV-C1 RNA was detected in 6/2,201 (0.27%) patients with hepatitis and 1/659 (0.15%) immunocompromised persons. Including the previously reported case, eight HEV-C1 infections were identified, including five in patients who were immunosuppressed. Three patients had acute hepatitis, four had persistent hepatitis, and one had subclinical infection without hepatitis. One patient died of meningoencephalitis, and HEV-C1 was detected in cerebrospinal fluid. HEV-C1 hepatitis was generally milder than HEV-A hepatitis. HEV-C1 RNA was detected in 7/186 (3.76%) rats. One HEV-C1 isolate obtained from a rat captured near the residences of patients was closely related to the major outbreak strain. Conclusions HEV-C1 is a cause of hepatitis E in humans in Hong Kong. Immunosuppressed individuals are susceptible to persistent HEV-C1 infection and extrahepatic manifestations. Subclinical HEV-C1 infection threatens blood safety. Tests for HEV-C1 are required in clinical laboratories.

Viral hepatitis E infection affects up to 80-100 % of domestic pigs worldwide and is characterized by high seroprevalence among domestic pigs in temperate climate countries. Epizootic monitoring of HEV infection is insufficient in the Republic of Belarus due to lack of the required number of available and inexpensive diagnostic ELISA kits with good sensitivity and specificity. In this regard, research on development of domestic ELISA kit for semi-quantitative detection of antibodies to hepatitis E virus in pigs with subsequent assessment of seroprevalence to I IEV in pig population in the Republic of Belarus is relevant. The results of studies on development of enzyme-linked immunosorbent assay kit for semi-quantitative determination of class G immunoglobulins to HEV in pig blood serum using recombinant proteins, including immunodominant amino acid sequences corresponding to the ORF2 and ORF3 proteins of HEV genotype 3 are presented in the paper. The optimal concentration for sorption of ORF2 and ORF3 proteins has been determined, which is 2 mu g/ml and 1 mu g/ml, respectively. The diagnostic sensitivity of this test kit makes 94.8 %, and the diagnostic specificity makes 100 %. Coefficients of variation being the criterion for assessing the intra-serial and inter-serial reproducibility of this test kit, make 3.5 % and 12.4 %, respectively, which allows to obtain reproducible results and identify specific anti-HEV antibodies in all positive samples of pig blood serum. When studying 1235 pig sera samples from various pig farms of Brest, Vitebsk, Gomel, Grodno, Minsk and Mogilev regions, seroprevalence of anti-HEV antibodies has been determined in 168 or 13.6 % of animals. The described diagnostic method can be widely used in science and practice for the further study of seroprevalence of anti-HEV.