Sponges play host to viruses

Marine sponges play host to a complex range of microorganisms which vary in abundance and diversity among species. While the current understanding of sponge-microbe interaction has dramatically increased recently, very little is known about how sponges and their microbiota interact with viruses. Many studies in the past have only alluded to the potential importance of viruses in areas such as sponge disease. Pascelli et al., 2018, aimed to bridge this gap in knowledge using three transmission electron microscopy preparation methods to provide the first-ever comprehensive morphological evaluation of sponge-associated viruses. Overall, across sponge cells  50 unique morphologies of viral-like particles (VLPs), with the frequent detection of multiple viral morphotypes highlighting a large number of potential hosts. Non-enveloped, non-tailed icosahedral VLPs were the most abundant morphology found. The study lacked a quantitative method, so future directions of this study would aim to include a quantitative method to count the number of VLPs per given area of tissue. In conclusion, the use of TEM confirmed that sponges are hosts to not only a diverse community of microorganisms but also a diverse community of viruses which allows for future research into characterising the taxonomy and function of viral sponge communities.

Pascelli, C., Laffy, P., Kupresanin, M., Ravasi, T. and Webster, N. (2018). Morphological characterisation of virus-like particles in coral reef sponges. PeerJ, 6, p.e5625.