台灣地區第二型登革病毒的分子流行病學與其流行潛力探究
Date Issued
2004-07-31
Date
2004-07-31
Author(s)
金傳春
DOI
922320B002165
Abstract
The largest epidemic of dengue hemorrhagic fever (DHF) with the highest
morbidity, mortality, and case fatality rate (CFR ：8.7%) in recent sixty years exploded
in southern Taiwan in 2002, since 1942. The causing agent of this DHF epidemic was
primarily due to dengue virus serotype 2 (DENV-2). How could the different
isolates of DENV-2 change over years in Taiwan is very important to be understood.
We investigated the molecular changes of viral factors in this epidemic in KaoHsiung
City/County and Pingtung City/County during 2001-2003 by elucidating the
molecular changes in nucleotide and amino acid sequences of complete envelope (E)
gene (1485 nucleotides) of DENV-2 through collecting the viral isolates obtained
from 2001-2003 compared with those from past epidemics in Taiwan and other
countries from GenBank through phylogenetic and qualitative analyses.
To determine the role of viral evolution in emerging a large-scale epidemic of
DHF during 2001-2003, we analyzed the complete sequences of E gene of 38
DENV-2 isolates obtained from epidemics in 1981, 1987, 1997, and 2001-2003 in
Taiwan. The maximum-likelihood phylogenet tree
analysis revealed that Taiwan's
DENV-2 isolates fell into 2 clusters (diversity 0~8.7%). The 2001-2003 ’s DEN V-2
isolates, which belonged to the cosmopolitan genotype, showed 99.1%~100%
sequence identity and 8, 20 and 2 DENV-2 isolates of 2001, 2002 and 2003 had
99.6-100%, 99.5-100% and.99.7% homology, respectively. The 1981's DEN V-2 isolate had 95.3 % nthomology with 1987's and such an identity dropped to 94.4% in
1997, and declined to 92.6% in 2001-2003. The nucleotide sequences of E gene at
positions of 137,291,1128 of 2001's eight DEN V-2 isolates had consistent changes
from C, A, T to T (only one remained as C), T, C in 2002-2003's twenty-two isolates
whereas the amino acid at position 46 was consistently changed from Thr in 2001 to I lein 2002 as the epidemic became longer.Tungkang's DEN V-2 isolates showed
geographic differences from Kaohsiung's DEN V-2 isolates in both 2001 and 2002,
implying different environmental factors or selective pressures affecting various
evolution rate or directions of DENV-2. Unfortunately, there were no molecular
signatures of distinct lineage for those isolates from DHF vs. DF or dengue cases with
or without specific underlying diseases.
In summary, the Cosmopolitan genotype of DENV-2 came into Taiwan in 2001
and increased its diversity in 2002-2003 plus geographical variation taken together
had facilitated to emerge more variants of DENV-2. Therefore, future studies on
quasispecies of DENV-2 in host with different conditions and investigate pathogenesis
of DHF between virus evolution and alternating hosts through transmission chains.
SDGs
Publisher
臺北市：國立臺灣大學公共衛生學院流行病學研究所
Type
report
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