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Abstract

Viruses depend on cell metabolism for their own propagation. The need to foster an intimate relationship with the host has resulted in the development of various strategies designed to help virus escape from the defense mechanisms present in the host. Over millions of years, the unremitting battle between pathogens and their hosts has led to changes in evolution of the immune system. Snake venoms are biological resources that have antiviral activity, hence substances of significant pharmacological value. The biodiversity in Brazil with respect to snakes is one of the richest on the planet; nevertheless, studies on the antiviral activity of venom from Brazilian snakes are scarce. The antiviral properties of snake venom appear as new promising therapeutic alternative against the defense mechanisms developed by viruses. In the current study, scientific papers published in recent years on the antiviral activity of venom from various species of snakes were reviewed. The objective of this review is to discuss the mechanisms of resistance developed by viruses and the components of snake venoms that present antiviral activity, particularly, enzymes, amino acids, peptides and proteins.Key words: snake venom, viruses, antiviral agents. Review ARticle The Journal of Venomous Animals and Toxins including Tropical Diseases ISSN 1678-9199 | 2011 | volume 17 | issue 4 | pages 387-393 INTRODUCTIONViruses are obligate intracellular parasites that depend on cell metabolism for their own propagation. This intimate virus-cell relationship led viruses to develop numerous survival strategies aimed at protecting themselves from the host defense system (1-4).One of the criteria for a successful viral infection is the ability to remain inside the host cell for the time required to allow replication of the viral genomic nucleic acid, envelopment and the production of new infectious virus progeny. The first barrier to be overcome is the host innate immune response (5).The association between virus persistence and disease in the host may lead to a long term relationship that does not result in any chronic virus-induced symptoms or in a fatal disease (6). Persistent viral infections constitute an example of immune evasion and, consequently, a successful relationship (7). Antiviral therapy has changed the natural history of numerous viral infections, delaying progression of the disease, improving the quality of life of infected individuals and reducing the frequency of hospitalization (8-10). Nevertheless, one of the principal problems today is therapeutic failure, including antiviral drug resistance (11, 12).The rich biodiversity in Brazil is an important source of wealth, since the country is home to at least 14% of the world's species, giving it an enormous advantage over other countries with poorer biodiversity, principally in a century in which biotechnology is expected to play such an important role in the global economy (13). Snake venoms are composed of a mixture of proteins and peptides (90-95%), but also include free amin...

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

“…Animal venoms contain a wide range of biologically active compounds of different chemical structures, and have proven to have not only significant pharmacological value but also great potential for drug discovery, with many snake venom components being investigated in preclinical or clinical trials for a variety of therapeutic applications [14][15][16][17][18][19][20][21][22]. Among snake venom enzymes, phospholipase A 2 s (PLA 2 s) are one of the main components [23].…”

Antiviral activity of animal venom peptides and related compounds

“…Other compounds found in snake venoms that exhibit antiviral activity are the phospholipases A 2 (PLA 2 ). Among their biological effects, they seem to interact with the host cells and prevent the intracellular release of virus capsid protein, suggesting that they block viral entry into the cells before virion uncoating [7,49,62]. The PLA 2 isolated from Crotalus durissus terrificus venom (PLA 2 -Cdt, Table 2) HIV human immunodeficiency virus, HSV herpes simplex virus, IAV influenza virus, VSV vesicular stomatitis virus, DENV dengue virus.…”

“…Another example of the antiviral effect of biomolecules extracted from snake venoms are the metalloprotease inhibitors, which could prevent the production of new HIV particles by inhibiting the viral proteases [50]. In addition, Immunokine® (OXO Chemie, Thailand), an oxidized derivative of the α-toxin extracted from Naja siamensis venom (Table 2), has been shown to inhibit infection of lymphocytes by HIV through the chemokine receptors CCR5 and CXCR4 [7,66].…”

“…Cecropins, isolated mostly from the hemolymph of infected pupae of the silk moth Hyalophora cecropia, but also from other insects, tunicates and Ascaris nematodes, are a family of AMPs, containing 35-37 amino acid residues arranged in two amphiphilic α-helices linked by a Gly-Pro hinge. Synthetic hybrid peptides, namely cecropin A (1-8)-magainin 2 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), exhibited potent antiviral activity by a mechanism mainly based on the compound hydrophobicity and α-helical content, inhibiting the virushost cell fusion [85] (Table 2).…”

“…All these facts together have propelled the prospection for new antiviral drugs, particularly from natural products, as they constitute more than 25% of the new drug prototypes approved in the last decades [4]. Among sources of natural products, animal venoms have revealed a great potential for drug discovery [5][6][7], and despite the harmful action mechanism of animal venoms, most of them have components holding potential medicinal properties to cure diseases.…”