The wolf in a wolfskin - A novel way to deal with harmful algal blooms

Harmful algal blooms (HAB) are a global issue of the modern world. Human population grows and so the input of algae food sources like phosphorus and nitrogen fertilizers to aquatic ecosystems. Heterocapsa circularisquama, a dinoflagellate widely distributed from Japan to Hong-Kong is not only a risk to human health. Their toxic blooms, an so the blooms of may other algae species, can cause a physical blockade of marine animals gills, generation of reactive oxygen species and toxins. So far H. cicularisquama blooms had a huge economically impact on the clam and fish farms industry and might soon show ecologically consequences on the marine food chain.

The HcRNAV single stranded RNA virus, that infects and lyses H. circularisquama was found in bottom sediments surrounding bloom areas. Based on their ecology, such native algicidal viruses have been considered a potential modality for the biological control of HABs, but there are doubts; their dispersal could lead to further disturbance of the aquatic ecosystem.

Kang et al. (2014) recently had a novel idea of how to the deliver algicidal compounds to harmful algae, but avoid further disturbance of the ecosystem.

First, a capsid protein of HcRNAV34 – single-stranded RNA virus was expressed in and purified from Escherichia coli and was then self-assembled into VLPs in vitro. Virus like particles are in all aspects really similar to the actual virus and share the same appropriate host specificity, but are unable to replicate in cells. A chemically synthesized algicidal compound (thiazolidinedione 49, TD49) was then encapsidated into HcRNAV 34 VLPs.

In the following experiment to test the efficiency of the new compound, TD49-encapsidated VLPs showed a more potent target-specific algicidal effect than TD49 alone.

Although I believe that the effects of such modification of marine viruses needs to be further studied, target-specific VLPs used for the delivery of cytotoxic compounds to nuisance algae seem to provide a safe environmentally friendly approach.

Even though Kang et al. (2014) idea is great, I believe it is also necessary to concentrate on and prevent the actual problem rather then having to deal with the consequences (Figure 1).

Fig.1:  A man trying to clean up dead fish killed by a HAB. Only one of many shocking photographs showing the extend of pollution all over the world.

Something else to think of; after infecting the blooms with TD49-encapsidated VLPs, the algae biomass will not just disappear. Dead sinking algal biomass leads to the depletion of oxygen and may result in long-term benthic hypoxic zones. Such zones have been previously associated with the occurrence of jellyfish blooms, another global issue at the moment…

Kang BS, Eom CY, Kim W, Kim PI, Ju SY, Ryu J, Han GH, Oh JI, Cho H, Baek SH, Kim G, Kim M, Hyun J, Jin E, Kim SW (2014) Construction of target-specific virus-like particles the delivery of algicidal compounds to harmful algae. Environmental Microbiology: doi:10.1111/1462-2920.12650