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J. Virol., 09 1997, 6501-6508, Vol 71, No. 9
AS Muerhoff, DB Smith, TP Leary, JC Erker, SM Desai and IK Mushahwar
Phylogenetic analysis of 44 GB virus C (GBV-C) 5'-untranslated region
(5'-UTR) sequences from 37 individuals suggested the presence of GBV-C
genotypes (A. S. Muerhoff, J. N. Simons, T. P. Leary, J. C. Erker, M. L.
Chalmers, T. J. Pilot-Matias, G. J. Dawson, S. M. Desai, and I. K.
Mushahwar, J. Hepatol. 25:379-384, 1996) that correlated with geographic
origin: type 1, 2a and 2b, and 3 isolates are found predominantly in West
Africa, the United States and Europe, and Japan, respectively. We have
extended our analysis to include 5'-UTR sequences from 129 globally
distributed GBV-C isolates and sequences from the second envelope protein
(E2) gene and nonstructural (NS) regions 3 and 5b from a subset of these
isolates. Bootstrap analysis of a 157- nucleotide segment of the 5'-UTR
from 129 sequences provided weak support for the existence of the four
major groups of GBV-C isolates previously described, although phylogenetic
analysis of a 374- nucleotide segment of the 5'-UTR from 83 isolates
provided stronger support. Thus, the groups of GBV-C variants previously
identified upon analysis of the entire 5'-UTR can be distinguished by
analysis of the shorter, 374-nucleotide region from the 5'-UTR. In
contrast, independent analysis of the E2, NS3, or NS5b region sequences
does not identify groups of GBV-C variants that correlate with geographic
origin. However, bootstrap analysis of these coding sequences, when linked
to form colinear sequences, demonstrates that longer coding regions can
produce GBV-C groupings that are similar to that determined from 5'-UTR
sequence analysis. The inability to distinguish between GBV- C variants by
using small segments of coding sequence suggests that the GBV-C genome is
constrained. As a result of these constraints, there is a high degree of
nucleotide and amino acid sequence conservation between isolates from
widely separated geographic areas. Hence, substitutions at many nucleotide
positions are not tolerated, so that substitutions at the positions which
can change are saturated, thereby obscuring the evolutionary relationships.
Copyright © 1997, American Society for Microbiology
Identification of GB virus C variants by phylogenetic analysis of 5'- untranslated and coding region sequences
Virus Discovery Group, Abbott Laboratories, North Chicago, Illinois 60064, USA. muerhoffs@randb.abbott.com
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