Discovery of broadly-neutralizing antibodies against brown recluse spider and Gadim scorpion sphingomyelinases using consensus toxins as antigens

Broadly-neutralizing monoclonal antibodies are becoming increasingly important tools for treating infectious diseases and animal envenomings. However, designing and developing broadly-neutralizing antibodies can be cumbersome using traditional low-throughput iterative protein engineering methods. Here, we present a new high-throughput approach for the standardized discovery of broadly-neutralizing monoclonal antibodies relying on phage display technology and consensus antigens representing average sequences of related proteins. We showcase the utility of this approach by applying it to toxic sphingomyelinases from the venoms of species from very distant orders of the animal kingdom, the recluse spider and Gadim scorpion. First, we designed a consensus sphingomyelinase and performed three rounds of phage display selection, followed by DELFIA-based screening and ranking, and benchmarked this to a similar campaign involving cross-panning against recombinant versions of the native toxins. Second, we identified two scFvs that not only bind the consensus toxins, but which can also neutralize sphingomyelinase activity of native whole venom in vitro. Finally, we conclude that the phage display campaign involving the use of the consensus toxin was more successful in yielding cross-neutralizing scFvs than the phage display campaign involving cross-panning.

Morphological Study of Hemiscorpius Peters, 1861 (Scorpiones: Hemiscorpiidae) in Hormozgan Province, Southern Iran

Hemiscorpius species are distributed in Africa and Asia. Seven species of this genus have been identified in Iran of which six species have been reported from Hormozgan province. Members of this genus are the most dangerous scorpions in Iran. corpions were collected by moving stones during the day and searching at night using portable UV lights from 2011 to 2022 from different areas in Hormozgan province. Three species were identified from Hormozgan province including Hemiscorpius acanthocercus, H.enischnocela and H. shahii which are endemic to Iran. These species have limited distribution and were reported only from the south of Iran. The number of trichobothria are 3, 10-12 and 15-17 in H. acanthocercus, H. enischnochela and H. shahii, respectively. The measured values showed that H. Shahii is larger than H. enischnochela and H. acanthocercus. Specimens of H. acanthocercus are brown to dark brown samples with dark metasomal segment V. There have been reports of death from biting this species. Members of H. enischnochela are light brown to yellow samples. Members of H. Shahii are large brown samples. All three species have sexual dimorphism. Although these three species can be distinguished based on their morphological characters, the molecular investigation is needed to confirm the validity of all species of this genus. Identifying species and determining their distribution range is very useful in facilitating education and treatment management.

The First Report of the Dangerous Scorpion Hemiscorpius acanthocercus from Hormoz Island in the Persian Gulf

The Article Abstract is not available.

Antigenic and Substrate Preference Differences between Scorpion and Spider Dermonecrotic Toxins, a Comparative Investigation

The Hemiscorpius lepturus scorpion and brown spider Loxosceles intermedia represent a public health problem in Asia and America, respectively. Although distinct, these organisms contain similar toxins responsible for the principal clinical signs of envenomation. To better understand the properties of these toxins, we designed a study to compare recombinant Heminecrolysin (rHNC) and rLiD1, the major phospholipase D toxins of scorpion and spider venom, respectively. Using a competitive ELISA and a hemolytic inhibition test, we come to spot a cross reaction between scorpion and spider venoms along with an epitopic similarity between rHNC and rLiD1 associated with neutralizing antibodies. Results show that the ability of the rHNC to hydrolyze lysophosphatidylcholine (LPC) is equivalent to that of rLiD1 to hydrolyze sphingomyelin and vice-versa. rHNC exclusively catalyze transphosphatidylation of LPC producing cyclic phosphatidic acid (cPA). The in-silico analysis of hydrogen bonds between LPC and toxins provides a possible explanation for the higher transphosphatidylase activity of rHNC. Interestingly, for the first time, we reveal that lysophosphatidic acid (LPA) can be a substrate for both enzymes using cellular and enzymatic assays. The finding of the usage of LPA as a substrate as well as the formation of cPA as an end product could shed more light on the molecular basis of Hemiscorpius lepturus envenomation as well as on loxoscelism.

Scorpionism by Hemiscorpius spp. in Iran: a review

Scorpions are distributed throughout Iran and the genus Hemiscorpius is particularly important in this region. Hemiscorpius lepturus is the most significant species within the genus in the country. Since scorpionism provoked by Hemiscorpius comprises a medical emergency, the present study is focused on this important issue. In order to perform the present work, a review of the medical and health-related literature was carried out in several databases. The current findings indicate that six species of Hemiscorpius are found in 15 states of Iran, mainly in the south and southwest. Deaths caused by stings were reported only for two species. The morphological characteristics and geographical distribution of H. lepturus in Iran, its venom and the toxic compounds, epidemiologic data and clinical manifestations of envenomation as well as treatment for affected people are herein reviewed and described. H. lepturus venom toxicity differs from other Iranian scorpions regarding duration and severity. Scorpionism is an important public health problem in Iran, especially in southwest and south regions and in urban areas. It is more prevalent in children and young people. H. lepturus venom is primarily a cytotoxic agent and has hemolytic, nephrotoxic and to some extent hepatotoxic activity. The use of polyvalent antivenom to prevent scorpion sting symptoms is recommended. A well-planned health education program might be useful in preventing scorpionism.

First report of death due to Hemiscorpius acanthocercus envenomation in Iran: Case report

Scorpion stings are significant causes of death in the western and southern regions of Iran. To date, reports have indicated that the H. lepturus species is the main cause of mortality due to scorpion stings. One of the species that belongs to this genus is Hemiscorpius acanthocercus (H. acanthocercus). This scorpion's venom is cytotoxic, and it causes pathological changes in the blood and can cause severe damage to the kidneys. The pain of Hemiscorpius' sting is mild and asymptomatic in the early hours. Delays in the treatment of these victims can cause hemolysis, hematuria, kidney failure, and even death. In this paper, we report the first known death due to an H. acanthocercus' sting in Iran.