Geographic distribution and evolution of yellow fever viruses based on direct sequencing of genomic cDNA fragments

Abstract

We have compared the nucleotide sequence of an envelope protein gene fragment encoding amino acids 291 to 406 of 22 yellow fever (YF) virus strains of diverse geographic and host origins isolated over a 63 year time span. The nucleotide fragment of viral RNA was examined by direct sequencing ofa PCR product derived from complementary DNA. Alignment with the prototype Asibi strain sequence showed divergence of 0 to 21'5 % corresponding to a maximum of 5-2 % divergence in the amino acid sequence. Taking 10% nucleotide divergence as a cut-off point, the 22 YF virus strains fell into three topotypes which corresponded to different geographical areas, namely West Africa, Central-East Africa, and South America. Two subgroups were defined in West Africa, a genotypic group circulating in the

Genetic variation among strains of wild-type yellow fever virus from Senegal.

“…This would suggest that, although these viruses were isolated from Senegal, Rendu belongs to a different topotype or genotype of wild-type YF viruses from Asibi, FVV and Dak1279, or the Senegalese isolates examined by Lepiniec et al (1994). Examination of the epidemiology of YF virus in Senegal [reviewed by Monath (1989)] supports the molecular data described in this paper.…”

“…Their nucleotide and amino acid sequence homology was studied over one-third of the genome (encoding the structural proteins and a non-structural protein, NS2A). We demonstrate that Rendu is different from all other West African wild-type YF viruses analysed to date, whereas FVV and Dak1279 are very closely related at the genetic level to each other and to previously studied YF viruses (Lepiniec et al, 1994 ;Chang et al, 1995). Table 1 shows the origins of the viruses used in this study.…”

“…Wild-type YF virus strains have been relatively poorly studied in recent years (Clarke, 1960 ;Deubel et al, 1985Gould et al, 1985 ;Lepiniec et al, 1994 ;Chang et al, 1995). The entire nucleotide and deduced amino acid sequence is available for only two strains of wild-type YF virus, the West African strains Asibi (Hahn et al, 1987), which was isolated in Ghana in 1927, and French viscerotropic virus (FVV) (Wang et al, 1995 Ballinger-Crabtree & Miller, 1990), the envelope (E) protein genes of 17 strains (Chang et al, 1995), and deduced from the 116 amino acids of the E protein from 22 wild-type strains isolated from different geographical regions of Africa (Lepiniec et al, 1994). This paper compares three wild-type YF viruses isolated from Senegal over a period of 38 years (strains FVV, Rendu and Dak1279).…”

“…Therefore, Rendu differed from all other YF virus strains sequenced to date at E-124, E-405 and E-407. Lepiniec et al (1994) reported the nucleotide sequence of 348 nucleotides in the E protein gene of 18 wild-type strains of YF virus from different parts of Africa. Rendu virus differs from the reference strain Asibi at 26 nucleotide positions, of which 6 are unique to strain Rendu.…”

“…Rendu virus differs from the reference strain Asibi at 26 nucleotide positions, of which 6 are unique to strain Rendu. Of the strains examined by Lepiniec et al (1994), the human isolate AMT\7 from the Ivory Coast in 1973 was most closely related to Rendu, with AMT\7 and Rendu viruses sharing 17 nucleotide differences from Asibi. However, at the amino acid level, Rendu was unique among all the other strains studied, including AMT\7, at position E-405.…”