We report a structural and functional
proteomics characterization
of venoms of the two subspecies (Bothrops bilineatus
bilineatus 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.
