Comparison of dengue-1 virus envelope glycoprotein gene sequences from French Polynesia

Dengue (DEN) is the leading arboviral infection of humans, with 100 million cases annually in the tropical areas of the world. The recent severe DEN-1 epidemic in French Polynesia in 2001, with an incidence rate of 16% and more than 45% of the cases with dengue hemorrhagic fever/dengue shock syndrome among 1,400 hospitalized children and eight fatalities, led us to study this new circulating strain. The entire envelope (E) gene of two French Polynesian DEN-1 virus isolates from the two epidemics of 1988-1989 (FP89) and 2001 (FP01) were sequenced and compared with 29 published DEN-1 virus E gene sequences. Phylogenetic relationships showed that the FP89 strain belonged to genotype V and the FP01 strain to genotype IV based on studies on the same region of DEN-1 virus genome (1,485 nucleotides). The recent dengue epidemic in French Polynesia in 2001 was probably due to the introduction of a new DEN-1 virus from Southeast Asia, since the minimum nucleotide divergence was 3.3% with A88, the Indonesian strain isolated in 1988 in Jakarta.