A new putative deltapartitivirus recovered from Dianthus amurensis

Identification and complete genome sequence of mulberry cryptic virus 1

A cryptic virus, named mulberry cryptic virus 1 (MuCV1), was identified in a mulberry (Morus alba) transcriptome dataset and confirmed using RACE methods. The genome of MuCV1 is composed of two double-stranded RNAs, 1605 bp and 1627 bp in size, encoding an RNA-dependent RNA polymerase (RdRp) and a coat protein (CP), respectively. The 5'-AGAAUU-3' sequence in the 5' untranslated region was conserved in the two dsRNAs. Sequence comparisons and phylogenetic analysis based on RdRp and CP sequences both indicated that MuCV1 is a deltapartitivirus (family Partitiviridae).

Complete nucleotide sequence of a novel partitivirus from Brassica campestris L. ssp. chinensis

In the present work, we report the discovery and complete genome sequence of a novel partitivirus identified from Brassica campestris L. ssp. chinensis, which we have named "Brassica campestris chinensis cryptic virus 1" (BCCV1). Next-generation sequencing (NGS) combined with adapter-ligation-mediated amplification allowed assembly of the full-length genome sequence of BCCV1. The genome of BCCV1 contains two dsRNA segments, dsRNA1 (1595 bp) and dsRNA2 (1591 bp), which encode a conserved RNA-dependent RNA polymerase (RdRp) and a putative capsid protein (CP), respectively. Homology searches and phylogenetic analysis of the 479-aa RdRp and 438-aa CP showed that BCCV1 is a new member of the genus Deltapartitivirus, family Partitiviridae. This is the first report of the identification of a member of the family Partitiviridae in Brassica campestris L. ssp. chinensis.

Detection and Characterization of Cucumis melo Cryptic Virus, Cucumis melo Amalgavirus 1, and Melon Necrotic Spot Virus in Cucumis melo

Three RNA viruses—Cucumis melo cryptic virus (CmCV), Cucumis melo amalgavirus 1 (CmAV1), and melon necrotic spot virus (MNSV)—were identified from a melon (Cucumis melo) transcriptome dataset. CmCV has two dsRNA genome segments; dsRNA-1 is 1592 bp in size, containing a conserved RNA-dependent RNA polymerase (RdRp), and dsRNA-2 is 1715 bp in size, and encodes a coat protein (CP). The sequence alignment and phylogenetic analyses of the CmCV RdRp and CP indicated CmCV clusters with approved or putative deltapartitiviruses in well-supported monophyletic clade. The RdRp of CmCV shared an amino acid sequence identity of 60.7% with the closest RdRp of beet cryptic virus 3, and is <57% identical to other partitiviruses. CmAV1 is a nonsegmented dsRNA virus with a genome of 3424 bp, including two partially overlapping open reading frames (ORFs) encoding a putative CP and RdRp. The sequence alignment and phylogenetic analyses of CmAV1 RdRp revealed that it belongs to the genus Amalgavirus in the family Amalgaviridae. The RdRp of CmAV1 shares 57.7% of its amino acid sequence identity with the most closely related RdRp of Phalaenopsis equestris amalgavirus 1, and is <47% identical to the other reported amalgaviruses. These analyses suggest that CmCV and CmAV1 are novel species in the genera Amalgavirus and Deltapartitivirus, respectively. These findings enrich our understanding of new plant dsRNA virus species.