Prevalence of a vertically transmitted single-stranded DNA virus in spinybacked orbweavers (emGasteracantha cancriformis/em) from Florida, USA

<p> Spiders (order Araneae, class Arachnida) are an important group of predatory arthropods in terrestrial ecosystems that have been recently identified as an untapped reservoir of single-stranded (ss)DNA viruses. Specifically, spiders harbour a diversity of ssDNA viruses encoding a replication-associated protein (Rep) within a circular genome. However, little is known about the ecology of novel circular Rep-encoding ssDNA (CRESS DNA) viruses. Here we investigated two CRESS DNA viruses recently identified in spinybacked orbweavers ( <em> Gasteracantha cancriformis </em> ), namely spinybacked orbweaver circular virus (SpOrbCV) 1 and 2. SpOrbCV-1 was detected in the majority (&gt; 65&hairsp;%) of spider specimens from all life stages, including eggs, spiderlings and adults, demonstrating that this virus is active within spinybacked orbweavers. In contrast, SpOrbCV-2 was only detected in adults at a lower (36 %) prevalence. Since we also detected SpOrbCV-2 in other spider species and this virus has been reported from a dragonfly, we suggest that SpOrbCV-2 is accumulated in these predators through common insect prey. The prevalence of SpOrbCV-1 in collected specimens allowed us to design assays to characterize this virus, which represents a new group of CRESS DNA viruses, the &lsquo;circularisviruses&rsquo;. To our knowledge, SpOrbCV-1 is the first example of a vertically transmitted virus in spiders, which may explain its high prevalence in spinybacked orbweavers. Since vertically transmitted viruses infecting insects (class Insecta) can manipulate their host&rsquo;s behaviour and physiology, future studies should investigate the ecological role of vertically transmitted viruses in spiders.</p>