Anionic Polysaccharides Exhibit Antiviral Activities to Vaccinia Virus


The aim of the present study was to characterise anti-vaccinia virus activities of anionic exopolysaccharides TK V3 isolated from cyanobacterium Arthrospira platensis and an exopolysaccharide isolated from the rhodophyt Porphyridium purpureum, respectively. These substances have previously been shown to be active against other enveloped viruses. We determined the in vitro inhibition of GFP-expressing vaccinia virus replication of 50 % at a concentration of 0.65 µg/ ml for EPS and of 0.78 µg/ml for TK V3. Substances also had an antiviral effect against ectromelia virus which is a most distinct orthopoxvirus genetically and the causative agent of mousepox. Anti-vaccinia virus and anti-ectromelia virus activities were demonstrated to increase with decreasing multiplicity of infection. Furthermore, non-toxic reduction of vaccinia virus in ovo replication was shown. Using time-of-addition assays, inhibition of viral entry by polyanionic substances was verified. EPS and TK V3 derived from phototrophic microorganisms represent novel anti-orthopoxvirus substances.

Vaccinia virus (VACV) belongs to the orthopoxvirus (OPV) genus and is closely related to variola virus, the causative agent of smallpox. The virions are generally enveloped, contain a double-stranded DNA and replicate within the cytoplasm. VACV represents the prototype of the OPV genus and had been successfully used as vaccine against smallpox which was declared eradicated in 1979. However, due to the severe adverse effects caused in a considerable proportion of vaccinees, vaccination was halted soon after eradication. Today, in the light of a decreasing immunity in the population, the potential abuse of variola virus for bioterrorist purposes is intensively discussed. Therefore, and with regard to the increasing number of zoonotic infections, the development of strategies to counteract OPV infections by introducing new therapeutic and prophylactic measures is widely accepted.

The Journal of Antivirals & Antiretrovirals (JAA) paves the way to discovery and development of antiviral drugs, compounds, and clinical methods to prevent viral infections. Importantly, JAA provides the opportunity to inform researchers, clinicians, and others working in the field of antiviral drugs and therapies.

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