Figure 1 Negative contrast electron micrograph of virions of Hepatitis E virus (HEV) in the bile fluid from a monkey challenged with the Mexico strain of human Hepatitis E virus. The bar represents 100 nm. (From Ticehurst, Rhodes, Krawczynski, Asher, Engler, Mensing, Caudill, Sjogren, Hoke, LeDuc, Bradley and Binn, 1992; with permission.)
Figure 2 Genome organization of Hepatitis E virus (HEV) (human strain Burma, Genbank Accession #M73218). The putative methyltransferase (MTR), protease (PRO), “X” (X), helicase (HEL), and RNA-dependent RNA polymerase (POL) domains are indicated.
Figure 3 Phylogenetic relationships of Hepatitis E virus (HEV) with the Picornaviridae, Caliciviridae, and Togaviridae. The helicase (HEL) and polymerase (POL) regions of the genome were analyzed. (Courtesy of Berke, T. and Matson, D.O.)
A. Partial gene sequences (200 amino acids) from the proposed helicase region were used for the phylogenetic analysis and included representative strains from each family. Clustal W v1.7 was used to create a multiple alignment for the amino acid sequences, which was verified by alignment of known motifs in the region (e.g., GxGKS/T). The nucleic acid sequences were added and aligned by hand using the corresponding amino acid sequences as template resulting in a consensus length of 608 nts. A phylogenetic tree was constructed from the nucleic acid sequence alignment using the maximum likelihood algorithm in the program DNAML from the PHYLIP 3.52c package within UNIX environment. For the algorithm, the global rearrangement option was invoked and the order of sequence input was randomized ten times. Other menu options were left as default. The resultant tree is unrooted and the phylogenetic distances are in the unit of expected number of substitutions per site. Branch points of the resulting tree had a confidence level of P<0.01 (P<0.05*). Genbank accession numbers for the strains in this analysis were M87661, X86557, U52086, U13992, Z69620, M67473, X86560, J02281, K02121, M22458, X00429, K02990, M15240, J02363, M73218, M80581, M74506, AF011921.
B. Partial gene sequences (200 amino acids) from the proposed polymerase region were used for the phylogenetic analysis and included representative strains from each family. Clustal W v1.7 was used to create a multiple alignment for the amino acid sequences, which was verified by alignment of known motifs in the region (e.g. SGxxxTxxxMT/S, GDD). The nucleic acid sequences were added and aligned by hand using the corresponding amino acid sequences as template resulting in a consensus length of 590 nts. A phylogenetic tree was constructed as described above and Genbank accession numbers for the strains in this analysis were identical to those above.
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