Viper Vipera Research Articles

Venom variation among the three subspecies of the North African mountain viper Vipera monticola Saint Girons 1953

The North African mountain viper (Vipera monticola) is a medically relevant venomous snake distributed in Morocco, Algeria, and Tunisia. Three subspecies of V. monticola, exhibiting differences in morphotypes and dietary regimes, are currently recognised: V. m. monticola, V. m. atlantica, and V. m. saintgironsi. Through the application of snake venomics, we analysed the venoms of specimens of Moroccan origin belonging to each of the three subspecies. Snake venom metalloproteinases (svMP), snake venom serine proteases (svSP), C-type lectin and C-type lectin-related proteins (CTL), and phospholipases A2 (PLA2) were predominant, with PLA2 being the most abundant toxin family overall. Disintegrins (DI) and cysteine-rich secretory proteins (CRISP) were exclusive to V. m. monticola and V. m. atlantica, while l-amino-acid oxidases (LAAO) were only found in V. m. saintgironsi. The differences detected in the venom profiles, as well as in presence/absence and relative abundances of toxin families, indicate the occurrence of intraspecific venom variation within V. monticola. The identified patterns of venom similarity between subspecies seem to align more with their phylogenetic relationships than with the reported differences in their feeding habits.

Barred, blotched or intermediate? A photographic-based survey on the spatial distribution of <em>Vipera aspis</em> phenotypes from central-southern Italy

Variation in animal colouration, which holds ecological and evolutionary significance, is evident in snakes, including the polytypic and highly polymorphic asp viper Vipera aspis. This species, currently acknowledged with four subspecies, features three of them (V. a. aspis, V. a. francisciredi and V. a. hugyi) within the Italian territory, each displaying distinct dorsal patterns. Analysing 143 georeferenced photos from personal surveys and citizen science, the present study explores transition areas between V. a. francisciredi and V. a. hugyi, revealing the coexistence of three dorsal pattern phenotypes (i.e. francisciredi, hugyi, and intermediate) across central-southern Italy. The outcome of the work reveals occurrences of francisciredi phenotypes considerably beyond the southern limit indicated in recent literature. Remarkably, intermediate phenotypes cover a significant portion of southern Italy, including Apulia (three records), Basilicata (six records) and Campania (three records) regions, and overlapping with both hugyi and francisciredi ranges. These findings suggest asymmetrical gene flow from northern to southern populations, resembling patterns observed in other reptiles. The intricate distribution of colour phenotypes underscores the necessity for molecular investigations to comprehend the genetic context and evolutionary history of V. aspis populations from central-southern Italy.

Analytical and quantitative assessment of the structural components of the adrenal glands of rats under the conditions of exposure to the venom of vipers Vipera berus berus and Vipera berus nikolskii

Snakebite envenoming is a common but neglected public health problem worldwide, especially in tropical countries. Annual mortality as a result of snakebites exceeds 138,000. It is believed that this problem is underestimated, and in many countries, individual cases of bites are not subject to proper fixation. The purpose of the study is the analytical and quantitative assessment of the structural components of the rats' adrenal glands under exposure to the venom of Vipers Vipera berus berus and Vipera berus nikolskii. Experimental studies were carried out on white, non-linear male rats. Vipera berus berus and Vipera berus nikolskii viper venom were obtained from V. N. Karazin Kharkiv National University. The freeze-dried native venom was stored at -20 °C and dissolved in saline immediately before the experiment. The animals were divided into three groups (control and 2 experimental groups) of 10 individuals each. Experimental rats were injected intraperitoneally in a physiological solution with a semi-lethal dose (LD50) (1.576 mg/g-1) of Vipera berus berus and Vipera berus nikolskii venoms. Animals of the control group were injected intraperitoneally with only a physiological solution. Rats were removed from the experiment 24 hours after exposure to the poison and anesthetised by cervical dislocation. Statistical analysis of the area of the microcirculatory channel and the nuclear-cytoplasmic index was performed using Fiji: ImageJ program and processed in Excel. Administration of the venom of the vipers Vipera berus berus and Vipera berus nikolskii to rats was accompanied by a significant increase in the area of the microcirculatory bed relative to the control group (2.9 times for Vipera berus berus and 6.5 times for Vipera berus nikolskii). Exposure to Vipera berus berus viper venom was associated with a significant decrease in the nuclear-cytoplasmic index in rats of the experimental group compared to the control group (13 % and 42 %, respectively), which is evidence of a decrease in the area of the nuclei of endocrinocytes of the adrenal cortex. This indicator in rats under the administration of Vipera berus nikolskii venom was even lower and amounted to 12 %. According to the statistical analysis of the quantitative assessment of the state of the cortical substance of the adrenal glands, it is worth noting the similar effect of the poisons of both types of snakes at the cellular level. At the same time, at the tissue level, the effect of Vipera berus nikolskii venom is more pronounced than that of Vipera berus berus - this is evidenced by the higher degree of disruption of the structure of the hemomicrocirculatory channel in the adrenal cortex of animals from the group that was affected by this venom. It led to an increase in the area of vessels due to their expansion and ruptures of their walls and haemorrhages into the surrounding parenchyma and stroma.

Effects of the Heterodimeric Neurotoxic Phospholipase A2 from the Venom of Vipera nikolskii on the Contractility of Rat Papillary Muscles and Thoracic Aortas.

Phospholipases A2 (PLA2s) are a large family of snake toxins manifesting diverse biological effects, which are not always related to phospholipolytic activity. Snake venom PLA2s (svPLA2s) are extracellular proteins with a molecular mass of 13-14 kDa. They are present in venoms in the form of monomers, dimers, and larger oligomers. The cardiovascular system is one of the multiple svPLA2 targets in prey organisms. The results obtained previously on the cardiovascular effects of monomeric svPLA2s were inconsistent, while the data on the dimeric svPLA2 crotoxin from the rattlesnake Crotalus durissus terrificus showed that it significantly reduced the contractile force of guinea pig hearts. Here, we studied the effects of the heterodimeric svPLA2 HDP-1 from the viper Vipera nikolskii on papillary muscle (PM) contractility and the tension of the aortic rings (ARs). HDP-1 is structurally different from crotoxin, and over a wide range of concentrations, it produced a long-term, stable, positive inotropic effect in PMs, which did not turn into contractures at the concentrations studied. This also distinguishes HDP-1 from the monomeric svPLA2s, which at high concentrations inhibited cardiac function. HDP-1, when acting on ARs preconstricted with 10 μM phenylephrine, induced a vasorelaxant effect, similar to some other svPLA2s. These are the first indications of the cardiac and vascular effects of true vipers' heterodimeric svPLA2s.

Sexual dimorphism and allometry in the head and body size of two viperid snakes (genus Vipera)

Sexual dimorphism in the size and shape of the body and head is the result of manifold selective pressures acting on organisms. In snakes, sexual size dimorphism is common and has been well-studied. However, intersexual differences in relative head size and shape have attracted far less attention. Similarly, the allometric properties of head shape and size in snakes are poorly known. Here, we analyse sexual dimorphism in two viperid species: European adder Vipera berus (Linnaeus, 1758) and Steppe viper Vipera renardi (Christoph, 1861). We measured body length, tail length and several head characteristics: head length, head width, head height, pileus length, interorbital distance and internarial distance. Our findings were that males and females of both species did not differ in body length (SVL), but that males tended to have significantly longer tails; there were also significant differences in head characteristics – males tended to have higher heads, and larger internarial and interorbital distances. The head dimensions displayed negative allometry when compared against SVL but when scaled against head length, dimensions like head height and head width exhibited positive allometry. We argue that these differences may be related to sexual selection and that the wider heads may also serve as antipredatory signal.

Scarfing - a novel agonistic behaviour between a copulating and a competing male northern viper Vipera berus

Scarfing - a novel agonistic behaviour between a copulating and a competing male northern viper Vipera berus

Dor beetle Anoplotrupes stercorosus found within the flank of a live northern viper Vipera berus

Dor beetle Anoplotrupes stercorosus found within the flank of a live northern viper Vipera berus

Возрастные различия лейкоцитарного состава крови обыкновенной гадюки Vipera berus (Reptilia: Serpentes: Viperidae)

The results of our comparative analysis of parameters of the leukocyte blood system of underyearlings and mature specimens of the common viper Vipera berus are presented. The material was the blood of 36 females and 26 males caught in the Middle Volga basin, and 13 underyearlings born in captivity from 4 females of this sample. V. b. berus underyearlings differed: from the females by a lower content of heterophils and azurophils, an increased content of eosinophils and basophils, an increase in the leukocyte shift index, a decrease in the lymphocytic–granulocytic index, the index of the of heterophil–eosinophil ratio, the index of the lymphocyte–eosinophil ratio; from the males by a reduced content of heterophils, an increased content of eosinophils and basophils, an increase in the leukocyte shift index, the index of the heterophil–eosinophil ratio, and the index of the lymphocyte–eosinophil ratio. In general, the adaptive response of the blood system of underyearlings indicated the later activation of lymphocytes as an effector link and the imbalance of the immune response due to the lack of a resource of immunocompetent cells (agranulocytes) compared with the indices of adults from natural populations.

Predation by a smooth snake Coronella austriaca of an aspic viper Vipera aspis in Spain

Predation by a smooth snake Coronella austriaca of an aspic viper Vipera aspis in Spain

Sex- and age-related variations in seasonal and circadian activity of the Nose-horned Viper Vipera ammodytes (Linnaeus, 1758)

The seasonal and circadian activity patterns of Vipera ammodytes were studied in five sites in western Bulgaria between 2014 and 2017. Vipera ammodytes was active from the end of February to the first half of November. In spring, adult males emerged a few weeks earlier than females and immature vipers. In autumn, the different sex/age groups started their hibernation approximately at the same time. We registered differences in the seasonal and circadian activities between the different sex/age groups. Adult males and subadults were mostly encountered during spring and autumn, and juveniles mainly in autumn, while the encounter rate of adult females was steady throughout the activity period. Females’ circadian activity varied according to their reproductive status. The observed patterns might be a result of the complex effects of many factors, such as climatic conditions, differences in the reproductive behaviour and the cost of reproduction between sexes, as well as the trade-off between precise thermoregulation, predation risk and foraging needs.

Comparative Study of the Effect of Snake Venoms on the Growth of Ciliates Tetrahymena pyriformis: Identification of Venoms with High Antiprotozoal Activity.

To search for compounds with antiprotozoal activity, effects of snake venoms on the ciliates Tetrahymena pyriformis was studied. T. pyriformis from subkingdom of Protozoa, including the protozoal pathogens, was used as a model organism to select the venoms that are the most active against parasitic protozoans. Various concentrations of venoms were added to the cells, and the cells that survived after 24 h were counted. Among the six snake species from the Viperidae family, the venom of the viper Vipera berus, which completely killed the cells at 49 μg/mL, was the most active. Among four species from the Elapidae family, the previously studied cobra venoms containing cytotoxins with strong antiprotozoal activity as well as the venom of krait Bungarus multicinctus (10 μg/mL) were the most active. The venoms of the pit vipers and Nikolsky's viper did not show any activity at 12.5 mg/mL. Thus, the venoms of V. berus and B. multicinctus are promising for the isolation of new antiprotozoal compounds.

Analysis of mammal mesopredator scat samples indicates significant predation on the endangered Hungarian meadow viper (Vipera ursinii rakosiensis)

Animal populations are regulated by multiple factors, e.g. resource availability, diseases and predators. However, these factors can be significantly influenced by anthropogenic effects (e.g. biological invasions, mesopredator release) and either subserve populations or push them towards local extinction. The Hungarian meadow viper Vipera ursinii rakosiensis is an endangered reptile, with only a few surviving populations following recent alterations and fragmentation of their habitats. In Hungary, all documented populations are located within nature conservation areas. Significant practical conservation efforts have been made, including habitat reconstruction and development, as well as ex situ breeding and reintroductions. Nevertheless, the estimated overall population size of Hungarian meadow viper remains very low, and the impact of conservation interventions is practically immeasurable according to low densities. It is hypothesized that predation is the main factor interfering with conservation efforts of the vipers. Here, we analysed the diet of two mammalian predators (European badger and red fox) in a Hungarian meadow viper habitat. We found a high prevalence of viper remains in the processed faecal samples, indicating that a high number of individuals vipers are subject to predation even within a short period of time. We conclude that effective predator control might be necessary to increase the impact of standard conservation measures (e.g. habitat development, ex situ breeding and reintroduction) that target the restoration of Hungarian meadow viper populations.

Snake venom phospholipase A2s exhibit strong virucidal activity against SARS-CoV-2 and inhibit the viral spike glycoprotein interaction with ACE2.

The COVID-19 pandemic caused by SARS-CoV-2 requires new treatments both to alleviate the symptoms and to prevent the spread of this disease. Previous studies demonstrated good antiviral and virucidal activity of phospholipase A2s (PLA2s) from snake venoms against viruses from different families but there was no data for coronaviruses. Here we show that PLA2s from snake venoms protect Vero E6 cells against SARS-CoV-2 cytopathic effects. PLA2s showed low cytotoxicity to Vero E6 cells with some activity at micromolar concentrations, but strong antiviral activity at nanomolar concentrations. Dimeric PLA2 from the viper Vipera nikolskii and its subunits manifested especially potent virucidal effects, which were related to their phospholipolytic activity, and inhibited cell–cell fusion mediated by the SARS-CoV-2 spike glycoprotein. Moreover, PLA2s interfered with binding both of an antibody against ACE2 and of the receptor-binding domain of the glycoprotein S to 293T/ACE2 cells. This is the first demonstration of a detrimental effect of PLA2s on β-coronaviruses. Thus, snake PLA2s are promising for the development of antiviral drugs that target the viral envelope, and could also prove to be useful tools to study the interaction of viruses with host cells.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00018-021-03985-6.

Unusual posture of a male northern viper Vipera berus – a more efficient way to bask?

Unusual posture of a male northern viper Vipera berus – a more efficient way to bask?

First finding of spirurid larva (Chromadorea, Spirurida) in the common European viper Vipera berus (Linnaeus, 1758) of the Russian fauna

The National park “Smolny” (Republic of Mordovia, Russia) is located in the Basin of Alatyr River, a second-order tributary of the Volga River. Favorable conditions are created for the development of helminths and infecting reptiles with them in floodplain biotopes. In 2018–2020 in this Protected Area we examined 25 individuals of the common viper Vipera berus (Linnaeus, 1758) by the method of complete helminthological dissection. We studied only road-killed vipers and reptiles killed by local residents. In total, eight species of helminths were registered in vipers: Leptophallus nigrovenosus, Telorchis assula, Alaria alata, larvae, Rhabdias fuscovenosa, Oswaldocruzia filiformis, Physocephalus sexalatus, larvae, Physaloptera clausa, larvae and Agamospirura minuta, larvae. Larva of spirurid nematodes Ph. sexalatus, Ph. clausa and A. minuta were recorded in the common viper for the first time in Russia. We found these nematode juveniles in walls and lining of stomach and intestine of snakes. We gave original drawings and morphological descriptions of these nematodes. Vipera berus was noted as a new host for Physaloptera clausa. Currently the helminth fauna of Vipera berus of the Russian fauna includes 15 species. Helminth infection of Vipera berus strongly depends on habitat and, especially, on the diet features. Snakes that live in dry habitats and feed on mouse-like rodents, as a rule, are weakly infested by helminths. Conversely, helminth infection is higher in vipers living in near-water habitats and feeding tailless amphibians. Participation of paratenic hosts in the helminth life cycles plays an important role in the distribution and preservation of parasites in the wild, and increases the invasion probability of the final hosts.

Variability of thermoregulation parameters of the common viper

The results of processing the data of continuous recording of body temperature using loggers obtained with the enclosure keeping 23 individuals of the common viper Vipera berus L. in Karelia (62.068310°N, 33.958824°E) are presented. Nine temperature characteristics, subdivided into 2 groups, were quantitatively evaluated – thermoecological, describing the dependence of the course of the viper’s body temperatures on the heat flux of the medium, and thermophysiological, stable parameters of thermoregulation. The factors that determine the variability of temperature characteristics are considered: time of day, weather conditions, morphometric indicators of an individual. A wide individual variability of thermoecological indicators and low variability of thermophysiological indicators were revealed, which was not associated with significant differences in different individuals. The parameter “maximum voluntary temperature”, which characterizes body temperature while avoiding overheating, is the closest to the physiological parameter of thermoregulation; obtaining such data is a very laborious process associated with deciphering the snake’s behavior from video recordings. An indicator that gives close values to the maximum voluntary temperature, which has a very simple calculation algorithm – “median active temperature (for a sample of temperatures above 30°C)”; however, it requires a volumetric series of continuously recorded temperature records for analysis. An accurate, statistically robust “maximum typical temperature” parameter gives an idea of the true maximum temperature characteristic of a species, but has a complex calculation method. These thermophysiological parameters are recommended to be used for intrapopulation and interspecies comparisons.

Behavioural interactions between barred grass snake Natrix helvetica and northern viper Vipera berus

Behavioural interactions between barred grass snake Natrix helvetica and northern viper Vipera berus

Observations on the diet of the nose-horned viper (Vipera ammodytes) in Greece

Observations on the diet of the nose-horned viper (Vipera ammodytes) in Greece

Micro-geographic shift between negligible and actuarial senescence in a wild snake.

While it has long been known that species have contrasted life expectancy (pace of mortality) and generation time (pace of reproduction), recent studies have also uncovered that the shape of adult age trajectories of mortality and reproduction can vary remarkably among species along a continuum of senescence ranging from strong deterioration (senescence), insignificant deterioration (negligible senescence) to improvement with advancing age (negative senescence). As for many long-lived ectotherms with asymptotic growth and increasing reproductive output with age, snakes are good candidates for negligible senescence to occur. Yet, intraspecific variation in the pace and shape of actuarial and reproductive senescence across wild populations of these species remains to be explored. Here, we used 37years of mark-recapture data in two nearby habitats inside a meadow viper Vipera ursinii population to quantify life expectancies, generation times and the shape of actuarial and reproductive senescence. Female vipers maintained stable reproductive performances at old ages, even when accounting for the predicted increase of fertility with body size, providing evidence for negligible reproductive senescence in both habitats. Males had a higher adult mortality and a shorter life expectancy on average than females and actuarial senescence shifted from negligible senescence in the optimal habitat to strong senescence in the sub-optimal habitat. Overall, these results demonstrate that micro-geographic environmental variation can generate qualitative shifts in actuarial senescence patterns. This highlights that taking into account the within-species plasticity of age-dependent trajectories could prove useful in better understanding what determines the evolution of life-history age trajectories.

Reptile responses to vegetation structure in a grassland restored for an endangered snake

Grassland ecosystems are among the most threatened biomes, and their restoration has become common in nature conservation. Yet restoration is rarely applied specifically for reptiles, which are among the most threatened vertebrates. The Meadow Viper (Vipera ursinii) has become extinct in most of lowland Europe, and an endangered subspecies (Vipera ursinii rakosiensis) has been a target of habitat restoration and captive breeding in Hungary since 2004. We quantified vegetation properties and the density of reptiles that either spontaneously colonised (three species) or were reintroduced (V. ursinii) in a grassland restored specifically for this purpose. We used a fine-scale survey to estimate the cover, and compositional and vertical diversity of the vegetation. We characterised sampling units along three habitat gradients: wetness, openness and grass tussock size. Model selection based on data from replicated counts showed that Green Lizards (Lacerta viridis) responded positively to vegetation cover and negatively to tussock area and height, and number of burrows. The Sand Lizard (Lacerta agilis) responded positively to vegetation cover, vertical diversity and wetness, and negatively to openness. The Balkan Wall Lizard (Podarcis tauricus) responded positively to tussock height and negatively to vegetation cover. Finally, V. ursinii responded positively to vegetation cover and tussock height, and negatively to compositional diversity. Our results show the general importance of structural and compositional diversity of vegetation to reptiles. These results suggest that adaptive management should focus on increasing the total cover (for lizards) and the structural diversity of vegetation (for each species) to benefit reptiles in restored grasslands.