Complete genome sequence of Mycoreovirus-1/Cp9B21, a member of a novel genus within the family Reoviridae, isolated from the chestnut blight fungus Cryphonectria parasitica

Abstract

Mycoreovirus 1 (MYRV-1) is the type species of the newly described genus Mycoreovirus of the large virus family Reoviridae. The virus was isolated from a hypovirulent strain (9B21) of the chestnut blight fungus, Cryphonectria parasitica. A previous study showed that double-shelled particles introduced to fungal spheroplasts resulted in stably infected colonies. Of the 11 double-stranded RNA genomic segments (S1-S11), the three largest (S1-S3) were sequenced previously and shown to have moderate levels of similarity to the homologous segments of mammal-pathogenic coltiviruses (Eyach virus and Colorado tick fever virus) and another fungus-infecting reovirus, Mycoreovirus 3 of Rosellinia necatrix strain W370 (MYRV-3/RnW370). The sequences of the remaining segments (S4-S11) are reported here. All of the segments have single ORFs on their positive strands and the terminal sequences 59-GAUCA----GCAGUCA-39 are conserved among currently and previously sequenced segments. Oligo-cap analysis showed that the positive strands of the genomic segments are capped, whereas the negative strands are not. Similarities among the four evolutionarily related viruses include low or moderate levels of amino acid sequence identity (14?7-34?2 %) and isoelectric points among equivalent polypeptides, e.g. proteins encoded by segments S4 and S5 of the four viruses. Phylogenetic analysis indicated that MYRV-1/Cp9B21 is related more closely to MYRV-3/RnW370 than to the coltiviruses. An interesting dissimilarity is found in codon-choice pattern among the four viruses, i.e. MYRV-1/Cp9B21 segments have a lower frequency of [XYG+XYC] than corresponding segments of the other viruses, suggesting a possible adjustment of virus codon usage to their host environments.

Effects of Defective Interfering RNA on Symptom Induction by, and Replication of, a Novel Partitivirus from a Phytopathogenic Fungus, Rosellinia necatrix

“…In accordance with this concept, strain C15 initially acquired all three types of particles, each including dsRNA1, dsRNA2, or DI-dsRNA1 segments, whereas C16 received only dsRNA1 and dsRNA2 particles ( (32). (E) Genetic organization of RnPV2.…”

“…RT-PCR with dsRNA templates was performed as described by Suzuki et al (32). The dsRNA fraction was prepared on a miniscale using CC41 cellulose (12) and denatured in the presence of dimethyl sulfoxide (33).…”

A Novel Victorivirus from a Phytopathogenic Fungus, Rosellinia necatrix, Is Infectious as Particles and Targeted by RNA Silencing

“…As shown in Fig. 1A (lane Rn-W1029), W1029 carried dsRNAs that migrated at the same position (ϳ5.2 kbp in size) as Helminthosporium victoriae virus 190S (HvV190S) and at the same position (ϳ2.3 kbp in size) as mycoreovirus 1 segment 4 (MyRV1 S4) (51). The slowly migrating dsRNA (S1 dsRNA) is the main subject of the present study and was found to be the genome of a novel victorivirus termed RnVV1-W1029 as stated below.…”

A Host Factor Involved in Hypovirus Symptom Expression in the Chestnut Blight Fungus, Cryphonectria parasitica

“…Table 1 shows the virus strains used: the prototype hypovirus CHV1-EP713 (28); its deletion mutants ⌬p29, ⌬p40b, and ⌬p69b (36); and the site-directed mutant Cys(72) (35). The type member of the genus Mycoreovirus, MyRV1-Cp9B21, was described previously (19,39).…”