Emerging options for the management of scorpion stings

Transcriptome analysis of scorpion species belonging to the Vaejovis genus

Scorpions belonging to the Buthidae family have traditionally drawn much of the biochemist's attention due to the strong toxicity of their venoms. Scorpions not toxic to mammals, however, also have complex venoms. They have been shown to be an important source of bioactive peptides, some of them identified as potential drug candidates for the treatment of several emerging diseases and conditions. It is therefore important to characterize the large diversity of components found in the non-Buthidae venoms. As a contribution to this goal, this manuscript reports the construction and characterization of cDNA libraries from four scorpion species belonging to the Vaejovis genus of the Vaejovidae family: Vaejovis mexicanus, V. intrepidus, V. subcristatus and V. punctatus. Some sequences coding for channel-acting toxins were found, as expected, but the main transcribed genes in the glands actively producing venom were those coding for non disulfide-bridged peptides. The ESTs coding for putative channel-acting toxins, corresponded to sodium channel β toxins, to members of the potassium channel-acting α or κ families, and to calcium channel-acting toxins of the calcin family. Transcripts for scorpine-like peptides of two different lengths were found, with some of the species coding for the two kinds. One sequence coding for La1-like peptides, of yet unknown function, was found for each species. Finally, the most abundant transcripts corresponded to peptides belonging to the long chain multifunctional NDBP-2 family and to the short antimicrobials of the NDBP-4 family. This apparent venom composition is in correspondence with the data obtained to date for other non-Buthidae species. Our study constitutes the first approach to the characterization of the venom gland transcriptome for scorpion species belonging to the Vaejovidae family.

Scorpion venom components as potential candidates for drug development

Scorpions are well known for their dangerous stings that can result in severe consequences for human beings, including death. Neurotoxins present in their venoms are responsible for their toxicity. Due to their medical relevance, toxins have been the driving force in the scorpion natural compounds research field. On the other hand, for thousands of years, scorpions and their venoms have been applied in traditional medicine, mainly in Asia and Africa. With the remarkable growth in the number of characterized scorpion venom components, several drug candidates have been found with the potential to tackle many of the emerging global medical threats. Scorpions have become a valuable source of biologically active molecules, from novel antibiotics to potential anticancer therapeutics. Other venom components have drawn attention as useful scaffolds for the development of drugs. This review summarizes the most promising candidates for drug development that have been isolated from scorpion venoms.

[Scorpion envenomation treated in the Infectious and Tropical Diseases at the Donka National Hospital, Guinea]

A retrospective descriptive study was conducted from 1(st) October 2010 to 30 November 2012 on the records of patients admitted for scorpion envenomation in the Department of Infectious and Tropical Diseases at the Donka National Hospital. The objective of this study is to describe the epidemiological profile and clinical characteristics of scorpion envenomation in Maritime Guinea, from scorpion stings recently covered in this service. We collected 75 cases of scorpion envenomation. The median age was 21.5 with interquartile 8 and 20 and sex ratio was 1.29. The upper limbs were involved in 55% of cases, followed by the lower limbs (35%), trunk (6%), head and neck (4%). We observed 63% of patients with local signs, 30% mild and general clinical signs of 7% severe systemic symptoms. All patients received an analgesic and a heterologous antitoxin, associated with an antibiotic (87% of patients), a corticosteroid (72%), diazepam (13%) and furosemide (34.6%). The incidence of scorpion envenomation is not negligible despite underreporting of cases, most often treated in traditional medicine.

Engineering venom's toxin-neutralizing antibody fragments and its therapeutic potential

Serum therapy remains the only specific treatment against envenoming, but anti-venoms are still prepared by fragmentation of polyclonal antibodies isolated from hyper-immunized horse serum. Most of these anti-venoms are considered to be efficient, but their production is tedious, and their use may be associated with adverse effects. Recombinant antibodies and smaller functional units are now emerging as credible alternatives and constitute a source of still unexploited biomolecules capable of neutralizing venoms. This review will be a walk through the technologies that have recently been applied leading to novel antibody formats with better properties in terms of homogeneity, specific activity and possible safety.

Mild reproductive effects of the Tityus bahiensis scorpion venom in rats

Background

Scorpion envenoming is a public health problem in Brazil, where Tityus serrulatus and T. bahiensis are considered the most dangerous scorpions. They are well adapted to urbanized environments, and there is an increasing probability of human exposure to these venoms, including during pregnancy. Not much is known about the effects of prenatal exposure to the venom, and no information is available to aid in the rational treatment of victims stung during pregnancy. Thus, this study aimed to investigate whether venom from the scorpion T. bahiensis administered once to pregnant female rats at a dose that causes a moderate envenomation may lead to deleterious effects on the reproductive performance of the dams and on the development of their offspring. This is the first work demonstrating that T. bahiensis venom, when administered experimentally to rats, alters maternal reproductive performance and the morphological development of fetuses. The venom was given to dams on the 5th (GD5) or on the 10th (GD10) gestational day. After laparotomy, on GD21, fetuses and placentas were counted, weighed and externally analyzed. The corpora lutea were counted. The sex and vitality of fetuses were evaluated, and each litter was then randomly divided for visceral or skeletal analyses. Data were analyzed by ANOVA followed by the Tukey-Kramer test and Fisher’s exact test. The significance level for all tests was set at p < 0.05.

Results

GD5 group presented an increased number of pre-implantation losses. Weight gains in fetuses and placentas were observed in the GD5 and GD10 groups. Weights of the heart and lungs were elevated in GD5 and GD10 and liver weight in GD10.

Conclusions

Moderate envenomation by T. bahiensis scorpion venom alters maternal reproductive performance and fetal development. However, these are preliminary results whose causes should be investigated more carefully in future studies.

Scorpion venom components that affect ion-channels function

The number and types of venom components that affect ion-channel function are reviewed. These are the most important venom components responsible for human intoxication, deserving medical attention, often requiring the use of specific anti-venoms. Special emphasis is given to peptides that recognize Na(+)-, K(+)- and Ca(++)-channels of excitable cells. Knowledge generated by direct isolation of peptides from venom and components deduced from cloned genes, whose amino acid sequences are deposited into databanks are nowadays in the order of 1.5 thousands, out of an estimate biodiversity closed to 300,000. Here the diversity of components is briefly reviewed with mention to specific references. Structural characteristic are discussed with examples taken from published work. The principal mechanisms of action of the three different types of peptides are also reviewed. Na(+)-channel specific venom components usually are modifier of the open and closing kinetic mechanisms of the ion-channels, whereas peptides affecting K(+)-channels are normally pore blocking agents. The Ryanodine Ca(++)-channel specific peptides are known for causing sub-conducting stages of the channels conductance and some were shown to be able to internalize penetrating inside the muscle cells.