Genetic Relationships of the Dengue Virus Serotypes

Abstract

SUMMARYPrevious studies have compared RNA genomes from the different dengue virus serotypes by cDNA-RNA hybridization using dengue-1 virus-and dengue-2 virusspecific cDNA probes. These probes revealed that there is a close genetic relationship between dengue virus serotypes 1 and 4. In this communication, the cDNA-RNA hybridization results using dengue-3-and dengue-4-specific cDNA probes to determine the genetic relatedness of all four dengue virus serotypes are reported. The results indicate that serotypes 1 and 4 are genetically very closely related (sharing about 70% of their genomes as detected by both the dengue-1 and dengue-4 CDNA probes), as are serotypes 3 and 4 (sharing about 50~o of their genomes as detected by both the dengue-3 and dengue-4 cDNA probes). Serotype 2 does not seem to be very closely related to the other dengue virus serotypes by cDNA-RNA hybridization analysis.Flaviviruses are a group of related viruses within the family Togaviridae, which replicate in arthropod and vertebrate cells. Some of these viruses cause major diseases such as Japanese encephalitis, yellow fever and dengue haemorrhagic fever in humans. Flaviviruses are subdivided by their reactions in serological tests. Each virus contains antigenic determinants common to the group, others which specify a complex of viruses and those which determine serotype specificity (Trent, t977). There are four dengue virus serotypes which form a discrete complex of flaviviruses (Porterfield, 1980), and each of these serotypes is associated with a wide range of clinical manifestations.Dengue viruses consist of a single-stranded RNA genome (about 12000 nucleotides long), a capsid protein (C), a low mol. wt. membrane protein (M) and an envelope glycoprotein (E) (for review, see Schlesinger, 1977). To determine the relatedness of dengue virus RNA genomes from each of the four serotypes, near full-length serotype-specific cDNA probes were synthesized and used in cDNA-RNA hybridization experiments. Studies with dengue-l-and dengue-2-specific cDNA probes were reported previously (Blok et al., 1984) and results with dengue-3-and dengue-4-specific probes are described below.Prototype viruses of the four dengue serotypes (dengue-l, Haw; dengue-2, NGC; dengue-3, H87; dengue-4, H241) were grown in the C6/36 clone of Aedes albopictus cells, and virus particles extruded into the medium were purified by polyethylene glycol precipitation. Viral RNA was extracted from the virus pellets and used either as a template for cDNA synthesis in vitro using an oligo(dT) primer and the enzyme reverse transcriptase, or in cDNA-RNA hybridization experiments as described earlier (Blok et al., 1984).In order to synthesize the amount of radioactively labelled cDNA needed for cDNA-RNA hybridization analyses, the concentrations of dengue-3-and dengue-4-specific RNA, of oligo (dT)12_18 primer, [32p]dCTP and avian myeloblastosis virus reverse transcriptase were increased tenfold over that used in previous studies with RNA from dengue-1 and dengue-2 serotypes (Blok et al., 198...

Variation in Dengue Type 2 Viruses Isolated in Bangkok during 1980

“…Analysis of the genomes of prototype strains of the four serotypes produced unique fingerprints for each, with only 7~ of large T1 oligonucleotides conserved (Vezza et al, 1980). DNA-RNA hybridizations between serotypes revealed sequence homologies of 23 to 73 ~ with most homology between types 1 and 4 and least homology between type 2 and other dengue serotypes (Blok, 1985). The relationships between 12 geographically distinct dengue-type 1 isolates assessed by oligonucleotide mapping were such that isolates from the same geographical area clustered into groups which shared a high degree of oligonucleotide homology (Repik et al, 1983).…”

Genetic and Epidemiological Studies of Dengue Type 2 Viruses by Hybridization Using Synthetic Deoxyoligonucleotides as Probes

“…nuclease resistance (Blok et al, 1984;Blok, 1985), lacks the sensitivity needed for detection of subtle genetic variation. Monoclonal antibody signature analysis is quite sensitive, and it correlates well with analysis by oligonucleotide fingerprinting.…”

“…Oligonucleotide fingerprinting of virus isolates is slow, expensive, and limited to laboratories with highly trained personnel. Other approaches for detecting genetic variation include one-dimensional analysis of RNase T1 fragments (A. V. Vorndam, personal communication), restriction endonuclease analysis of random primed single-stranded cDNA (Faragher et al, 1985), primer extension sequence analysis of specific genome regions (Ghosh et al, 1980), monoclonal antibody signature analysis (Wands et al, 1981 ;Monath et al, 1986) and RNA/DNA hybridization using cDNA probes (Blok et al, 1984;Blok, 1985). We have developed a novel method of obtaining information by the construction of specific short DNA probes for the rapid detection by RNA/DNA hybridization of DEN 2 genetic variants.…”

Caracterización epidemiológica del dengue en la Unidad de Terapia Intensiva Adultos. Hospital Central "Dr. Emilio Cubas" del Instituto de Previsión Social, Paraguay

“…La infección por un serotipo induce inmunidad de por vida contra el serotipo viral homólogo, pero solo tiene un efecto protector transitorio contra los demás tres serotipos (3,4).…”