Discovery of a New Virus from the Fungus Cordyceps Javanica

Jim Crocker
13th July, 2024

Discovery of a New Virus from the Fungus Cordyceps Javanica

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Qingdao Agricultural University discovered a new virus, CjNRSV1, in the fungus Cordyceps javanica, which infects insects
  • CjNRSV1 has a unique genome with three RNA segments, showing similarities to other viruses in the genus Laulavirus
  • This discovery enhances our understanding of mycoviruses and their potential use in biocontrol strategies for pest management
The virus family Phenuiviridae, which belongs to the order Hareavirales, includes a variety of segmented negative-sense single-stranded RNA viruses that infect a wide range of hosts, including animals, plants, protozoans, and fungi. In a recent study conducted by researchers at Qingdao Agricultural University, a novel phenuivirus was identified in the entomopathogenic fungus Cordyceps javanica, isolated from the small brown plant hopper Laodelphax striatellus. This virus has been tentatively named "Cordyceps javanica negative-strand RNA virus 1" (CjNRSV1)[1]. The genome of CjNRSV1 consists of three negative-sense single-stranded RNA segments, designated RNA1, RNA2, and RNA3, with lengths of 7252, 2401, and 1117 nucleotides, respectively. Notably, the 3'- and 5'-terminal regions of these RNA segments have identical sequences, and the termini are complementary to each other, a characteristic feature of viruses in the order Hareavirales. RNA1 encodes a large protein containing a conserved domain for the bunyavirus RNA-dependent RNA polymerase (RdRP) superfamily, with a 57-80% identity to the RdRP encoded by phenuiviruses in the genus Laulavirus. RNA2 encodes a protein similar to the movement protein (MP)-like protein of laulaviruses, while RNA3 encodes a protein with a conserved domain of the phenuivirid nucleocapsid protein superfamily. Phylogenetic analysis using the RdRPs of various phenuiviruses and other unclassified phenuiviruses revealed that CjNRSV1 groups with established members of the genus Laulavirus. This suggests that CjNRSV1 is a novel fungus-infecting member of this genus. Mycoviruses, or viruses that infect fungi, are widespread across all major fungal taxa. They are generally transmitted intracellularly during cell division, sporogenesis, and cell-to-cell fusion (hyphal anastomosis), lacking an extracellular phase in their life cycle. Their host ranges are typically limited to individuals within the same or closely related vegetative compatibility groups[2]. However, recent advances have expanded the experimental host ranges for some mycoviruses. While many mycoviruses do not significantly affect their hosts, those that reduce the virulence of phytopathogenic fungi are of particular interest for developing biocontrol strategies[2][3]. High-throughput virome analyses have led to the discovery of diverse viruses with unique genome structures and new lifestyles. This has filled many phylogenetic gaps and provided evolutionary insights. For example, the yado-kari/yado-nushi relationship between yadokariviruses and dsRNA viruses, and the hadaka nature of capsidless segmented RNA viruses, highlight the complex interactions and evolutionary pathways of mycoviruses[4]. The discovery of CjNRSV1 expands our understanding of the diversity and host range of phenuiviruses. This novel virus adds to the growing list of mycoviruses that infect entomopathogenic fungi, which are fungi that infect and kill insects. The identification of CjNRSV1 in Cordyceps javanica, a fungus known for its potential in biocontrol of insect pests, opens new avenues for research into the interactions between mycoviruses and their fungal hosts, and how these interactions can be leveraged for pest management. Furthermore, the study of CjNRSV1 contributes to the broader field of fungal virology, which has expanded to include not only plant pathogenic fungi but also insect and human pathogenic fungi. Mycoviruses can influence a range of phenotypes, including virulence, metabolite production, and drug resistance[5]. Understanding these interactions can lead to novel strategies for managing fungal diseases and improving fungal-based biocontrol methods. In summary, the identification of CjNRSV1 by Qingdao Agricultural University researchers is a significant addition to the field of mycovirology. This novel phenuivirus infects an entomopathogenic fungus, highlighting the complex and diverse nature of mycoviruses and their potential applications in biocontrol. This study builds on previous findings and expands our knowledge of the evolutionary relationships and functional roles of mycoviruses in different fungal hosts.

GeneticsBiochemMycology

References

Main Study

1) Identification of a novel member of the genus Laulavirus (family Phenuiviridae) from the entomopathogenic ascomycete fungus Cordyceps javanica.

Published 12th July, 2024

https://doi.org/10.1007/s00705-024-06069-5

Related Studies

2) 50-plus years of fungal viruses.

https://doi.org/10.1016/j.virol.2015.02.034

3) Viruses of plant pathogenic fungi.

https://doi.org/10.1146/annurev-phyto-080508-081932

4) Mycovirus Diversity and Evolution Revealed/Inferred from Recent Studies.

https://doi.org/10.1146/annurev-phyto-021621-122122

5) Mycoviruses and their role in fungal pathogenesis.

https://doi.org/10.1016/j.mib.2021.05.007


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