Hunting Drosophila viruses from wild populations: A novel isolation approach and characterisation of viruses

Author(s)

Bruner-Montero, Gaspar ; Luque, Carlos M. M. ; Cesar, Cassia Siqueira ; Ding, Shuai Dominique ; Day, Jonathan P. P. ; Jiggins, Francis Michael

• Document type: Journal article
• Source: PLOS PATHOGENS; v. 19, n. 3, p. 25-pg., 2023-03-01.

Abstract

Author summaryThere is known to be an enormous diversity of viruses that infect insects, but very few of these have been cultured in the laboratory, meaning that we know little about their biology. To help overcome this challenge we have generated cultured insect cells that are easily infected by viruses, and used a simple test that detects a wide variety of different viruses. This allowed us to isolate La Jolla virus and Newfield virus from Drosophila fruit flies. We found that in some species of Drosophila these are harmful pathogens that can kill or sterilise the insects that they infect, including the crop pest Drosophila suzukii. Therefore, a simple technique allowed us to isolate new viruses that are likely important pathogens of these insects in nature, and these viruses have the potential to be used to control pest species. Metagenomic studies have demonstrated that viruses are extremely diverse and abundant in insects, but the difficulty of isolating them means little is known about the biology of these newly discovered viruses. To overcome this challenge in Drosophila, we created a cell line that was more permissive to infection and detected novel viruses by the presence of double-stranded RNA. We demonstrate the utility of these tools by isolating La Jolla virus (LJV) and Newfield virus (NFV) from several wild Drosophila populations. These viruses have different potential host ranges, with distinct abilities to replicate in five Drosophila species. Similarly, in some species they cause high mortality and in others they are comparatively benign. In three species, NFV but not LJV caused large declines in female fecundity. This sterilization effect was associated with differences in tissue tropism, as NFV but not LJV was able to infect Drosophila melanogaster ovaries. We saw a similar effect in the invasive pest of fruit crops Drosophila suzukii, where oral infection with NFV caused reductions in the fecundity, suggesting it has potential as a biocontrol agent. In conclusion, a simple protocol allowed us to isolate new viruses and demonstrate that viruses identified by metagenomics have a large effect on the fitness of the model organism D. melanogaster and related species. (AU)

• FAPESP's process: 19/03997-2 - On the host-symbiont-natural enemy interaction: from parasitism to mutualism
• Grantee: Cássia de Souza Siqueira Cesar
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 21/13166-0 - Does Wolbachia affect virus diversity in an Aedes aegypti field population?
• Grantee: Cássia de Souza Siqueira Cesar
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate