Sequences of E/NS1 Gene Junction from Four Dengue‐2 Viruses of Northeastern Thailand and Their Evolutionary Relationships with Other Dengue‐2 Viruses

Abstract

We determined the 240-nucleotide sequences of the E/NS1 gene junction of four dengue-2 viruses by the primer extension dideoxy chain termination method. These viruses were isolated from dengue patients with different clinical severities in Nakhon Phanom, Northeastern Thailand in 1993. The results were compared with the 52 published dengue-2 sequences of the same gene region. Sequence divergence of four new isolates varied from 4.17% to 5.42% compared with dengue-2 prototype New Guinea C strain whereas it varied from 5.42% to 6.67% and from 6.67% to 7.09% when compared with Jamaica 1409 strain and PR159/S1 strain, respectively. All nucleotide substitutions were found at the 3rd position of the codons which were silent mutations. All 56 isolates studied were classified into five genotypic groups by constructing the dendrogram. The results indicated that four new isolates from Northeastern Thailand belong to genotype II of dengue virus serotype 2, and were most closely related to prototype New Guinea C strain. We also observed the variation in nucleotide and amino acid sequences among clusters of isolates (Thailand-1980, Malaysia-1989 and Thailand-1993 which were obtained from the dengue patients with different clinical severities. The significance of these genetic differences have been discussed in terms of the possible correlation between genetic variability and virulence.

Detection of the Disease Severity‐Related Molecular Differences among New Thai Dengue‐2 Isolates in 1993, Based on Their Structural Proteins and Major Non‐Structural Protein NS1 Sequences

“…The main objective of this study was to identify the disease severity-related molecular differences among four new Thai dengue-2 isolates, which may provide clues to the pathogenetic mechanisms of dengue virus infection. This work is the continuation of our previous study on the E/NS1 gene junction of the same viruses (64).…”

“…The nucleotide sequence of the inserted cDNA was determined by the primer extension dideoxy chain termination method (62) using the Taq Dye Deoxy Terminator Cycle Sequencing Kit (Applied Biosystems) as described elsewhere (64). Sequences covering the whole structural proteins were determined from cDNA clones of six overlapping gene regions ( Fig.…”

Antibodies Determine Virulence in Dengue

“…Many attempts have failed. In southeast Asia, essentially no differences were found in DENV 2 envelope proteins from viruses recovered from severe and mild disease, [18][19][20] in the 240 nucleotides of the E/NS1 junction of 73 DENG 2 isolated from Thai children with mild or severe dengue disease 21 or in the full length sequences of seven DENG 3 strains isolated between 1974 and 1998 from Indonesia and Thailand. 22 In some studies DENV 2 have been classified into "subtypes" that appear to be associated with either mild or severe disease.…”

Impact of dengue virus infection and its control

“…The E/NS1 junction of these viral genomes has been sequenced showing that all strains belonged to the same genotype II of dengue type 2 virus [13, 14]. Before sequencing, all strains were amplified once by inoculation to C6/36 cells, the infected culture fluid was harvested after 7 days incubation at 28°C, and stored in aliquots at −80°C.…”