We report a structural and functional proteomics characterization of
venoms of the two subspecies (Bothrops bilineatusbilineatus and B. b. smaragdinus) of the South American palm pit viper from the Brazilian state of Rondônia and B. b. smaragdinus from Perú. These poorly known arboreal and mostly nocturnal generalist predators are widely distributed in lowland rainforests throughout the entire Amazon region, where they represent an important cause of
snakebites. The three B. bilineatus spp.
venom samples exhibit overall conserved proteomic profiles comprising components belonging to 11
venom protein classes, with PIII (34-40% of the total
venom proteins) and PI (8-18%) SVMPs and their endogenous tripeptide inhibitors (SVMPi, 8-10%);
bradykinin-potentiating-like
peptides (BBPs, 10.7-15%);
snake venom serine proteinases (SVSP, 5.5-14%);
C-type lectin-like
proteins (CTL, 3-10%);
phospholipases A2 (PLA2, 2.8-7.6%);
cysteine-rich secretory
proteins (CRISP, 0.9-2.8%); l-
amino acid oxidases (LAO, 0.9-5%) representing the major components of their common
venom proteomes. Comparative analysis of the
venom proteomes of the two geographic variants of B. b. smaragdinus with that of B. b. bilineatus revealed that the two Brazilian taxa share identical molecules between themselves but not with Peruvian B. b. smaragdinus, suggesting hybridization between the geographically close, possibly sympatric, Porto Velho (RO, BR) B. b. smaragdinus and B. b. bilineatus parental populations. However, limited sampling does not allow determining the frequency of this event. The toxin arsenal of the South American palm pit vipers may account for the in vitro recorded collagenolytic, caseinolytic, PLA2,
l-amino acid oxidase,
thrombin-like and
factor X-activating activities, and the clinical features of South American palm pit viper envenomings, i.e., local and progressively ascending
pain,
shock and
loss of consciousness, spontaneous
bleeding, and profound coagulopathy. The remarkable cross-reactivity of the Brazilian pentabothropic SAB
antivenom toward the heterologous B. b. bilineatus
venom suggests that the paraspecific
antigenic determinants should have been already present in the
venom of the last common ancestor of the Bothrops ″jararaca″ and ″taeniatus″ clades, about 8.5 Mya in the mid-late Miocene epoch of the Cenozoic era. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the data set identifiers PXD020043, PXD020026, and PXD020013.