Phylogenetic analysis of hepatitis E virus isolates from Egypt.

Hepatitis E virus (HEV) genome was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in fecal samples of two sporadic cases of hepatitis E in Cairo Egypt. Sequence of the complete putative structural region [open reading frame (ORF)-2] and complete region of unknown function (ORF-3) was determined for the two HEV isolates. Phylogenetic analysis of the nucleotide sequences was performed using neighbor joining or maximum parsimony methods of tree reconstruction. Direct correspondence between the HEV evolutionary trees and geographic origin of the HEV isolates was observed. Three genotypes of HEV were identified: genotype I (Asia-Africa), genotype II (US), and genotype III (Mexico). Genotype I was further divided into two subgenotypes (Asia and Africa). In the Asian subgenotype, three smaller genetic clusters were observed (China-like sequences, Burma-like sequences, and sequence from a fulminant case of HEV). The segregation of all these genetic clusters was supported by the high level of bootstrap probabilities. Four regions of the HEV genome were used for phylogenetic analysis. In all four regions, Egyptian HEV isolates were grouped in a separate African clade.