Intraspecific venom variation in the medically important puff adder (Bitis arietans): Comparative venom gland transcriptomics, in vitro venom activity and immunological recognition by antivenom.

Background: Variation in snake venoms is well documented, both between and within species, with intraspecific venom variation often correlated with geographically distinct populations. The puff adder, Bitis arietans, is widely distributed across sub-Saharan Africa and into the Arabian Peninsula where it is considered a leading cause of the ~310,000 annual snakebites across the region, with its venom capable of causing substantial morbidity and mortality. Despite its medical importance and wide geographic distribution, there is little known about venom variation between different B.

Investigating Snake-Venom-Induced Dermonecrosis and Inflammation Using an Ex Vivo Human Skin Model.

Snakebite envenoming is a neglected tropical disease that causes >100,000 deaths and >400,000 cases of morbidity annually. Despite the use of mouse models, severe local envenoming, defined by morbidity-causing local tissue necrosis, remains poorly understood, and human-tissue responses are ill-defined. Here, for the first time, an ex vivo, non-perfused human skin model was used to investigate temporal histopathological and immunological changes following subcutaneous injections of venoms from medically important African vipers ( and ) and cobras ( and ).

Dermonecrosis caused by a spitting cobra snakebite results from toxin potentiation and is prevented by the repurposed drug varespladib.

Snakebite envenoming is a neglected tropical disease that causes substantial mortality and morbidity globally. The venom of African spitting cobras often causes permanent injury via tissue-destructive dermonecrosis at the bite site, which is ineffectively treated by current antivenoms. To address this therapeutic gap, we identified the etiological venom toxins in venom responsible for causing local dermonecrosis.

Assessing Target Specificity of the Small Molecule Inhibitor MARIMASTAT to Snake Venom Toxins: A Novel Application of Thermal Proteome Profiling.

New treatments that circumvent the pitfalls of traditional antivenom therapies are critical to address the problem of snakebite globally. Numerous snake venom toxin inhibitors have shown promising cross-species neutralization of medically significant venom toxins in vivo and in vitro. The development of high-throughput approaches for the screening of such inhibitors could accelerate their identification, testing, and implementation and thus holds exciting potential for improving the treatments and outcomes of snakebite envenomation worldwide.

Distinct regulatory networks control toxin gene expression in elapid and viperid snakes.

Background: Venom systems are ideal models to study genetic regulatory mechanisms that underpin evolutionary novelty. Snake venom glands are thought to share a common origin, but there are major distinctions between venom toxins from the medically significant snake families Elapidae and Viperidae, and toxin gene regulatory investigations in elapid snakes have been limited. Here, we used high-throughput RNA-sequencing to profile gene expression and microRNAs between active (milked) and resting (unmilked) venom glands in an elapid (Eastern Brown Snake, Pseudonaja textilis), in addition to comparative genomics, to identify cis- and trans-acting regulation of venom production in an elapid in comparison to viperids (Crotalus viridis and C.

Niemann-Pick Type C2 Proteins in : Molecular Modelling and Prediction of Their Structure-Function Relationships.

is a major vector that transmits arboviruses through the saliva injected into the host. Salivary proteins help in uninterrupted blood intake and enhance the transmission of pathogens. We studied Niemann-Pick Type C2 (NPC2) proteins, a superfamily of saliva proteins that play an important role in arbovirus infections.

Midgut transcriptomic responses to dengue and chikungunya viruses in the vectors Aedes albopictus and Aedes malayensis.

Dengue (DENV) and chikungunya (CHIKV) viruses are among the most preponderant arboviruses. Although primarily transmitted through the bite of Aedes aegypti mosquitoes, Aedes albopictus and Aedes malayensis are competent vectors and have an impact on arbovirus epidemiology. Here, to fill the gap in our understanding of the molecular interactions between secondary vectors and arboviruses, we used transcriptomics to profile the whole-genome responses of A.

Metabolic Processes Are Differentially Regulated During Wild-Type and Attenuated Dengue Virus Infection in Aedes aegypti.

Successful completion of the dengue virus (DENV) life cycle in its mosquito vectors is important for efficient human-mosquito-human cycle of transmission, but the virus-mosquito interactions that underpin this critical event are poorly defined. To understand the virus-host interactions that determine viral infection by Aedes aegypti, the principal DENV vector, the authors compared transcriptomic changes in the head/thorax of the mosquito after intrathoracic infection with the wild-type DENV2 16681 strain and its attenuated derivative, PDK53. Using high-throughput RNA-sequencing, the authors identified 1,629 differentially expressed genes (DEGs) during 16681 infection, compared with only 22 DEGs identified during PDK53 infection, indicating that 16681 infection triggers a more robust host transcriptomic response compared with PDK53 infection.

High resolution proteomics of Aedes aegypti salivary glands infected with either dengue, Zika or chikungunya viruses identify new virus specific and broad antiviral factors.

Arboviruses such as dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV) viruses infect close to half a billion people per year, and are primarily transmitted through Aedes aegypti bites. Infection-induced changes in mosquito salivary glands (SG) influence transmission by inducing antiviral immunity, which restricts virus replication in the vector, and by altering saliva composition, which influences skin infection. Here, we profiled SG proteome responses to DENV serotype 2 (DENV2), ZIKV and CHIKV infections by using high-resolution isobaric-tagged quantitative proteomics.

Integration of transcriptomic and proteomic approaches for snake venom profiling.

Introduction: Snake venoms contain many protein and peptide isoforms with high levels of sequence variation, even within a single species.

Areas Covered: In this review, we highlight several examples, from both published and unpublished work in our lab, demonstrating how a combined venom gland transcriptome and proteome methodology allows for comprehensive characterization of venoms, including those from understudied rear-fanged snake species, and we provide recommendations for using these approaches.

Expert Opinion: When characterizing venoms, peptide mass fingerprinting using databases built predominately from protein sequences originating from model organisms can be disadvantageous, especially when the intention is to document protein diversity.

The RNA binding protein Quaking represses splicing of the Fibronectin EDA exon and downregulates the interferon response.

Quaking (QKI) controls RNA metabolism in many biological processes including innate immunity, where its roles remain incompletely understood. To illuminate these roles, we performed genome scale transcriptome profiling in QKI knockout cells with or without poly(I:C) transfection, a double-stranded RNA analog that mimics viral infection. Analysis of RNA-sequencing data shows that QKI knockout upregulates genes induced by interferons, suggesting that QKI is an immune suppressor.

JNK pathway restricts DENV2, ZIKV and CHIKV infection by activating complement and apoptosis in mosquito salivary glands.

Arbovirus infection of Aedes aegypti salivary glands (SGs) determines transmission. However, there is a dearth of knowledge on SG immunity. Here, we characterized SG immune response to dengue, Zika and chikungunya viruses using high-throughput transcriptomics.

Interspecific and intraspecific venom enzymatic variation among cobras (Naja sp. and Ophiophagus hannah).

The genera Ophiophagus and Naja comprise part of a clade of snakes referred to as cobras, dangerously venomous front-fanged snakes in the family Elapidae responsible for significant human mortality and morbidity throughout Asia and Africa. We evaluated venom enzyme variation for eleven cobra species and three N. kaouthia populations using SDS-PAGE venom fingerprinting and numerous enzyme assays.

Cysteine-Rich Secretory Proteins (CRISPs) From Venomous Snakes: An Overview of the Functional Diversity in A Large and Underappreciated Superfamily.

The CAP protein superfamily (Cysteine-rich secretory proteins (CRISPs), Antigen 5 (Ag5), and Pathogenesis-related 1 (PR-1) proteins) is widely distributed, but for toxinologists, snake venom CRISPs are the most familiar members. Although CRISPs are found in the majority of venoms, very few of these proteins have been functionally characterized, but those that have been exhibit diverse activities. Snake venom CRISPs (svCRISPs) inhibit ion channels and the growth of new blood vessels (angiogenesis).

Omics Technologies for Profiling Toxin Diversity and Evolution in Snake Venom: Impacts on the Discovery of Therapeutic and Diagnostic Agents.

Snake venoms are primarily composed of proteins and peptides, and these toxins have developed high selectivity to their biological targets. This makes venoms interesting for exploration into protein evolution and structure-function relationships. A single venom protein superfamily can exhibit a variety of pharmacological effects; these variations in activity originate from differences in functional sites, domains, posttranslational modifications, and the formations of toxin complexes.

Exploring Toxin Evolution: Venom Protein Transcript Sequencing and Transcriptome-Guided High-Throughput Proteomics.

Studying animal toxin evolution requires sequences of these proteins and peptides, and transcript sequences allow for the construction of cladograms and evaluation of selection pressures from nonsynonymous and synonymous nucleotide mutation ratios. In addition, these translated sequences can be useful as custom databases for peptide identifications within venoms and for better proteomic quantification. Obtaining these transcripts is achieved by sequencing cDNA originating from venom gland tissue or venom.

Proteomic Deep Mining the Venom of the Red-Headed Krait, .

The use of -omics technologies allows for the characterization of snake venom composition at a fast rate and at high levels of detail. In the present study, we investigated the protein content of Red-headed Krait () venom. This analysis revealed a high diversity of snake venom protein families, as evidenced by high-throughput mass spectrometric analysis.

Transcriptome-facilitated proteomic characterization of rear-fanged snake venoms reveal abundant metalloproteinases with enhanced activity.

High-throughput technologies were used to identify venom gland toxin expression and to characterize the venom proteomes of two rear-fanged snakes, Ahaetulla prasina (Asian Green Vine Snake) and Borikenophis portoricensis (Puerto Rican Racer). Sixty-nine complete toxin-coding transcripts from 12 venom protein superfamilies (A. prasina) and 50 complete coding transcripts from 11 venom protein superfamilies (B.

Adaptive evolution of distinct prey-specific toxin genes in rear-fanged snake venom.

Venom proteins evolve rapidly, and as a trophic adaptation are excellent models for predator-prey evolutionary studies. The key to a deeper understanding of venom evolution is an integrated approach, combining prey assays with analysis of venom gene expression and venom phenotype. Here, we use such an approach to study venom evolution in the Amazon puffing snake, , a generalist feeder.

Toxins Are an Excellent Source of Therapeutic Agents against Cardiovascular Diseases.

Venomous and hematophagous animals use their venom or saliva for survival, to obtain food, and for self-defense. Venom and saliva from these animals are cocktails of bioactive molecules primarily composed of proteins and peptides. These molecules are called toxins because they cause unwanted consequences on prey.

Transcriptomics-guided bottom-up and top-down venomics of neonate and adult specimens of the arboreal rear-fanged Brown Treesnake, Boiga irregularis, from Guam.

Unlabelled: The Brown Treesnake (Boiga irregularis) is an arboreal, nocturnal, rear-fanged venomous snake native to northern and eastern regions of Australia, Papua New Guinea and the Solomon Islands. It was inadvertently introduced onto the island of Guam during the late 1940's to early 1950's, and it has caused massive declines and extirpations of the native bird, lizard, and mammal populations. In the current study, we report the characterization of the venom proteome of an adult and a neonate B.

Transcriptomic Signatures of Tacaribe Virus-Infected Jamaican Fruit Bats.

Tacaribe virus (TCRV) is a mammalian arenavirus that was first isolated from artibeus bats in the 1950s. Subsequent experimental infection of Jamaican fruit bats () caused a disease similar to that of naturally infected bats. Although substantial attention has focused on bats as reservoir hosts of viruses that cause human disease, little is known about the interactions between bats and their pathogens.