Characterization of Two Novel Toti-Like Viruses Co-infecting the Atlantic Blue Crab, Callinectes sapidus, in Its Northern Range of the United States

Abstract

The advancement of high throughput sequencing has greatly facilitated the exploration of viruses that infect marine hosts. For example, a number of putative virus genomes belonging to the Totiviridae family have been described in crustacean hosts. However, there has been no characterization of the most newly discovered putative viruses beyond description of their genomes. In this study, two novel double-stranded RNA (dsRNA) virus genomes were discovered in the Atlantic blue crab (Callinectes sapidus) and further investigated. Sequencing of both virus genomes revealed that they each encode RNA dependent RNA polymerase proteins (RdRps) with similarities to toti-like viruses. The viruses were tentatively named Callinectes sapidus toti-like virus 1 (CsTLV1) and Callinectes sapidus toti-like virus 2 (CsTLV2). Both genomes have typical elements required for −1 ribosomal frameshifting, which may induce the expression of an encoded ORF1–ORF2 (gag-pol) fusion protein. Phylogenetic analyses of CsTLV1 and CsTLV2 RdRp amino acid sequences suggested that they are members of two new genera in the family Totiviridae. The CsTLV1 and CsTLV2 genomes were detected in muscle, gill, and hepatopancreas of blue crabs by real-time reverse transcription quantitative PCR (RT-qPCR). The presence of ~40 nm totivirus-like viral particles in all three tissues was verified by transmission electron microscopy, and pathology associated with CsTLV1 and CsTLV2 infections were observed by histology. PCR assays showed the prevalence and geographic range of these viruses, to be restricted to the northeast United States sites sampled. The two virus genomes co-occurred in almost all cases, with the CsTLV2 genome being found on its own in 8.5% cases, and the CsTLV1 genome not yet found on its own. To our knowledge, this is the first report of toti-like viruses in C. sapidus. The information reported here provides the knowledge and tools to investigate transmission and potential pathogenicity of these viruses.

Identification and Genome Characterization of a Novel Virus within the Genus Totivirus from Chinese Bayberry (Myrica rubra)

“…The genus Totivirus contains viruses that initially infect fungi or protozoa [ 6 , 7 ]. However, more and more totiviruses or totivirus-like viruses have been found in a series of other eukaryotic hosts, including, but not limited to: mosquitoes [ 8 ], ants [ 9 ], fish [ 10 ], crabs [ 11 ], and plants [ 5 , 12 ]. The species demarcation criteria within the genus Totivirus is not entirely clear.…”

Metagenomic of Liver Tissue Identified at Least Two Genera of Totivirus-like Viruses in Molossus molossus Bats

“…Artivirus, for instance, has demonstrated infectivity in arthropods such as the Atlantic blue crab and the mosquito Armigere subalbatus totivirus [ 52 , 53 ]. Pistolvirus, on the other hand, has been found to infect fish species like the Atlantic salmon and golden carp [ 38 , 51 ].…”

Molossus molossus bats encompass at least two distinct genera of totivirus-like

“…Researchers have also proposed three new genera within the Totiviridae family, namely Artivirus, Pistolvirus, and Tricladiviris [39,45,48,49,51,52]. For instance, Artivirus has been found to infect arthropods such as the Atlantic blue crab [53] and the mosquito Armigere subalbatus totivirus [54]. Pistolvirus has been found to infect fish species such as the Atlantic salmon and golden carp [39,52].…”