Viome of parasitic nematodes
Screening published transcriptomes, we have discovered 75 novel RNA viruses that infect 27 species of parasitic nematodes, responsible for >1.5 billion infections in people and animals. Our analysis shows extensive diversity and a conserved global spread of virus/nematode associations across multiple continents suggesting an ancestral acquisition event and host-virus co-evolution. Characterization of viruses of Brugia malayi (BMRV1) and Onchocerca volvulus (OVRV1) shows that virus is abundant in reproductive tissues of adult parasites suggestive of a sexual/vertical transmission. One striking feature was the presence of BMRV1 RNA in epicuticular inflations in older parasites. BMRV1 and OVRV1 elicit antibody responses from the vertebrate host demonstrating direct exposure to the immune system. The parasites that host these viruses affect billions of people and animals with an intimate and continuous exposure throughout life. These viruses will advance our understanding of parasitic nematode diseases and are a potential hidden reservoir of emerging viral diseases.