Regional divergence of phospholipase A2-like protein cDNAs between New Guinean and Australian Pseudechis australis

The relative efficacy of chemically diverse small-molecule enzyme-inhibitors against anticoagulant activities of Black Snake (Pseudechis spp.) venoms

Snakebite remains a worldwide public health burden and a severely neglected tropical disease. Recent research has begun to focus on the potential use of repurposed small-molecule enzyme-inhibitors as early treatments to neutralise the effects of snake venoms. Black snakes (Pseudechis spp.) are a widespread and dangerously venomous group found throughout Australia and New Guinea. Utilising validated coagulation assays, our study assessed the efficacy of two chemically different small molecule inhibitors, a phospholipase A₂ inhibitor (varespladib) and a metalloproteinase inhibitor (prinomastat), in vitro neutralisation of the anticoagulant prothrombinase-inhibiting activity of venom from seven species within the Pseudechis genus (P. australis, P. butleri, P. coletti, P. guttatus, P. papuanus, P.rossignolii, P. sp (NT).). Varespladib was shown to be highly effective at neutralising this anticoagulant activity for all seven species, but with P. coletti notably less so than the others. In contrast, prinomastat showed strong neutralisation for five out of the seven species, but was ineffective at neutralising the activity of P. coletti or P. rossignolii venoms. This suggests that varespladib binds to a highly conserved site but that prinomastat binds to a more variable site. These results build upon recent literature indicating that metalloproteinase inhibitors have cross-neutralising potential towards snake venom phospholipase A₂ toxins, but with higher degrees of variability that PLA2-specific inhibitors. An important caveat is that these are in vitro tests and while suggestive of potential clinical utility, in vivo animal testing and clinical trials are required as future work.

Confronting taxonomic vandalism in biology: conscientious community self-organization can preserve nomenclatural stability

Self-published taxon descriptions, bereft of a basis of evidence, are a long-standing problem in taxonomy. The problem derives in part from the Principle of Priority in the International Code of Zoological Nomenclature, which forces the use of the oldest available nomen irrespective of scientific merit. This provides a route to ‘immortality’ for unscrupulous individuals through the mass-naming of taxa without scientific basis, a phenomenon referred to as taxonomic vandalism. Following a flood of unscientific taxon namings, in 2013 a group of concerned herpetologists organized a widely supported, community-based campaign to treat these nomina as lying outside the permanent scientific record, and to ignore and overwrite them as appropriate. Here, we review the impact of these proposals over the past 8 years. We identified 59 instances of unscientific names being set aside and overwritten with science-based names (here termed aspidonyms), and 1087 uses of these aspidonyms, compared to one instance of preference for the overwritten names. This shows that when there is widespread consultation and agreement across affected research communities, setting aside certain provisions of the Code can constitute an effective last resort defence against taxonomic vandalism and enhance the universality and stability of the scientific nomenclature.

Proteomics and antivenomics of Papuan black snake (Pseudechis papuanus) venom with analysis of its toxicological profile and the preclinical efficacy of Australian antivenoms

The Papuan black snake (Pseudechis papuanus Serpentes: Elapidae) is endemic to Papua New Guinea, Indonesian Papua and Australia's Torres Strait Islands. We have investigated the biological activity and proteomic composition of its venom. The P. papuanus venom proteome is dominated by a variety (n≥18) of PLA₂s, which together account for ~90% of the venom proteins, and a set of low relative abundance proteins, including a short-neurotoxic 3FTx (3.1%), 3-4 PIII-SVMPs (2.8%), 3 cysteine-rich secretory proteins (CRISP; 2.3%) 1-3 l-amino acid oxidase (LAAO) molecules (1.6%). Probing of a P. papuanus cDNA library with specific primers resulted in the elucidation of the full-length nucleotide sequences of six new toxins, including vespryn and NGF not found in the venom proteome, and a calglandulin protein involved in toxin expression with the venom glands. Intravenous injection of P. papuanus venom in mice induced lethality, intravascular haemolysis, pulmonary congestion and oedema, and anticoagulation after intravenous injection, and these effects are mainly due to the action of PLA₂s. This study also evaluated the in vivo preclinical efficacy of Australian black snake and polyvalent Seqirus antivenoms. These antivenoms were effective in neutralising the lethal, PLA₂ and anticoagulant activities of P. papuanus venom in mice. On the other hand, all of the Seqirus antivenoms tested using an antivenomic approach exhibited strong immunorecognition of all the venom components. These preclinical results suggest that Australian Seqirus¹ antivenoms may provide paraspecific protection against P. papuanus venom in humans.

SIGNIFICANCE PARAGRAPH

The toxicological profile and proteomic composition of the venom of the Papuan black snake, Pseudechis papuanus, a large diurnal snake endemic to the southern coast of New Guinea and a handful of close offshore islands, were investigated. Intravenous injection of P. papuanus venom in mice induced intravascular hemolysis, pulmonary congestion and edema, anticoagulation, and death. These activities could be assigned to the set of PLA₂ molecules, which dominate the P. papuanus venom proteome. This study also showed that Australian Seqirus black snake or polyvalent antivenoms were effective in neutralising the lethal, PLA₂ and anticoagulant activities of the venom. These preclinical results support the continued recommendation of these Seqirus antivenoms in the clinical management of P. papuanus envenoming in Australia, Papua New Guinea or Indonesian Papua Province.

Pr-SNTX, a short-chain three-finger toxin from Papuan pigmy mulga snake, is an antagonist of muscle-type nicotinic acetylcholine receptor (α2βδε)

Three-finger toxins (3FTxs) are one of the major components in snake venoms. In this study, we isolated a cDNA encoding a short-chain 3FTx, Pr-SNTX, from Pseudechis rossignolii. The amino acid sequence of Pr-SNTX is nearly identical to that of its ortholog in Pseudechis australis. Pr-SNTX protein inhibited muscle-type (α2βδε), but not neuronal α7 nicotinic acetylcholine receptor (nAChR) activity.