Novel hepatitis E virus (HEV) isolates from Europe: Evidence for additional genotypes of HEV

Hepatitis E infection is associated with areas in which hepatitis E virus ( HEV) infection is endemic. Acute infections in industrialized nations are u sually linked to travel to endemic areas. Recently, an acute hepatitis infe ction in a patient from the United States (US), with no recent foreign trav el history, was linked to a novel strain of HEV. Although a few additional cases have been reported from patients who have not traveled to endemic are as, the source of these infections has not been determined. The objective o f this study was to identify additional HEV isolates from patients with acu te infection who had no recent history of travel to areas where HEV is cons idered endemic, and to determine the genetic relationship between these and other HEV isolates. Viral RNA was isolated from serum and polymerase chain reaction (PCR) was performed using consensus primers based on a number of HEV isolates. HEV sequence in open reading frame (ORF) 1 and ORF2 was ident ified in three patients from nonendemic areas, one from Italy and two from Greece. Comparative and phylogenetic analyses were performed. The Greek and Italian isolates were significantly divergent from two isolates from the U S and isolates identified previously from HEV-endemic regions. The Italian isolate was distinct from the two Greek isolates. In addition, the two Gree k isolates were significantly divergent from each other. Phylogenetic analy sis indicated that the Italian and two Greek isolates represent three new g enotypes of HEV, distinct from the Burmese, Mexican, and US genotypes. J. M ed. Virol. 57:243-251, 1999. (C) 1999 Wiley-Liss, Inc.