Sequences and structural organization of phospholipase A₂ genes from Vipera aspis aspis, V. aspis zinnikeri and Vipera berus berus venom

Abstract

We used a PCR-based method to determine the genomic DNA sequences encoding phospholipases A 2 (PLA2s) from the venoms of Vipera aspis aspis (V. a. aspis), Vipera aspis zinnikeri (V. a. zinnikeri), Vipera berus berus (V. b. berus) and a neurotoxic V. a. aspis snake (neurotoxic V. a. aspis) from a population responsible for unusual neurotoxic envenomations in south-east France. We sequenced five groups of genes, each corresponding to a different PLA2. The genes encoding the A and B chains of vaspin from the neurotoxic V. a. aspis, PLA2-I from V. a. zinnikeri, and the anticoagulant PLA2 from V. b. berus are described here. Single nucleotide differences leading to amino-acid substitutions were observed both between genes encoding the same PLA2 and between genes encoding different PLA2s. These differences were clustered in exons 3 and 5, potentially altering the biological activities of PLA2. The distribution and characteristics of the PLA2 genes differed according to the species or subspecies. We characterized for the first time genes encoding neurotoxins from the V. a. aspis and V. b. berus snakes of central France. Genes encoding ammodytins I1 and I2, described previously in Vipera ammodytes ammodytes (V. am. ammodytes), were also present in V. a. aspis and V. b. berus. Three different ammodytin I1 gene sequences were characterized: one from V. b. berus, the second from V. a. aspis, V. a. zinnikeri and the neurotoxic V. a. aspis, and the third from the neurotoxic V. a. aspis. This third sequence was identical with the reported sequence of the V. am. ammodytes ammodytin I1 gene. Genes encoding monomeric neurotoxins of V. am. ammodytes venom, ammodytoxins A, B and C, and the Bov-B LINE retroposon, a phylogenetic marker found in V. am. ammodytes genome, were identified in the genome of the neurotoxic V. a. aspis. These results suggest that the population of neurotoxic V. a. aspis snakes from south-east France may have resulted from interbreeding between V. a. aspis and V. am. ammodytes.

Venomics of Vipera berus berus to explain differences in pathology elicited by Vipera ammodytes ammodytes envenomation: Therapeutic implications

“…1). In accordance with our proteomic results, analysis of the sPLA 2 genes of Vbb from central France revealed the presence of genes encoding the VbbPLA 2 , AtnL, AtnI 1 and AtnI 2 [56]. Interestingly, genes of the A and B subunits of vaspin, a heterodimeric neurotoxin similar to vipoxin [57], were also detected in this study.…”

“…The main neurotoxins of Vaa venom are Atxs, presynaptically neurotoxic sPLA 2 s. These molecules were not detected in Vbb venom, either by specific antibodies or by sequencing. Although Vbb possesses genes encoding the neurotoxic sPLA 2 s [56], these are obviously expressed only occasionally and to a very limited extent. 2.…”

Sequence analysis and phylogenetic relationship of genes encoding heterodimeric phospholipases A2 from the venom of the scorpion Anuroctonus phaiodactylus

“…Concerning the genomic structure of the genes coding for the mature protein PLAs, groups I and II in general have three exons separating this region (Kordis et al, 1998;Jeyaseelan et al, 2000;Fujimi et al, 2002;Guillemin et al, 2003;Chijiwa et al, 2003). On the contrary, group III is highly variable, showing from two to six exons.…”

“…A comparative analysis of the introns of snake PLA2s shows some similarities in their nucleotide sequences (Fujimi et al, 2002;Guillemin et al, 2003), whereas in the Blast comparison we performed with the bee and scorpion PLA2 the similarities were practically non existent.…”

Efficacité variable de l’antivenin Viperfav® pour traiter les envenimations vipérines avec neurotoxicité

“…Cette espèce est caractérisée par la production d'une famille de neurotoxines appelées ammodytoxines induisant la présence d'anticorps anti-ammodytoxines dans l'antidote. Or les travaux récents [17][18][19][20][21] démontrent que toutes les neurotoxines de vipères aspics sont des phospholipases A2 proches des ammodytoxines et qui sont donc neutralisées par le Viperfav W grâce à une réaction croisée. Le protocole thérapeutique préconise ainsi de considérer tout signe de neurotoxicité comme un symptôme général dont la présence implique la cotation en grade 2 avec nécessité d'administrer le traitement antidotique [1,9,15].…”