Lentinula edodes negative-strand RNA virus 2 (LeNSRV2) is assigned to
Lentinuvirus lentinulae, the only species in the genus. The lentinuvirus genome comprises two segments of negative-sense RNA (RNA1) and an ambisense RNA (RNA2). Three genes encode two structural proteins, a large protein (L) and a nucleocapsid (N), and one non-structural protein likely functioning as a viral movement protein (MP) that enables cell-to-cell movement in plant hosts. Based on well-supported Maximum Likelihood or Maximum Clade Credibility trees inferred from complete L protein sequences, viruses classified in the genus Lentinuvirus form a monophyletic cluster clearly distinguished from other phenuivirids (Lin et al., 2019).
Virion morphology is unknown. Based on the putative proteins encoded by the virus genome, the virion is probably a filamentous virion without an envelope.
Nucleic acid and Protein
The lentinuvirus genome consists of two single-stranded segments of RNA1 (7.1 kb) and RNA2 (2.8 kb). The terminal nucleotides of each segment occur in a canonical, conserved sequence (in coding sense) 5′-ACACAAAGAC…GUCUUUGUGU-3′ and may form the panhandle structures typical of other members of the order Bunyavirales (Table 2.Phenuiviridae). In silico analysis of lentinuvirus putative ORF sequences suggests that the lentinuvirus genome encodes two proteins with predicted molecular masses of 367 kDa and 35 kDa, homologous with the bunyaviral RNA-directed RNA polymerase (RdRP) domain and the tenuivirus/phlebovirus N domain, respectively. The genome may also encode third protein of 48 kDa hat shares sequence homology and/or structural characteristics with the MP of plant viruses (Table 3.Phenuiviridae) (Lin et al., 2019).
Genome organization and replication
Lentinuvirus genome arrangement is similar to that of entoviruses (Figure 1.Lentinuvirus). The lentinuvirus genome encompasses two segments of negative-sense RNA: RNA1, encoding the L protein that is the putative RdRP, and the ambisense RNA2, which is transcribed by the RdRP to form a subgenomic virus-complementary mRNA that encodes N from a viral antigenome RNA2, and also transcribed to form a subgenomic virus-sense mRNA that encodes MP from a viral genome RNA2. The two ORFs on RNA2 are separated by a noncoding intergenic region that potentially forms a long A/U rich stem-loop structure. Details of virus replication are unknown (Lin et al., 2019, Kormelink et al., 2021, Rodriguez Coy et al., 2022).
|Figure 1.Lentinuvirus. Genome organization of a lentinuvirus. Coloured boxes depict ORFs that encode N, nucleocapsid protein and L, large protein. A white box depicts an ORF that encodes MP, non-structural cell-to-cell movement protein.|
LeNSRV2 was detected by high-throughput sequencing of RNA from a shiitake [Lentinula edodes ((Berk.) Pegler, 1976)] collected in Japan (Lin et al., 2019).
Species demarcation criteria
Not defined as the genus currently includes only a single species.