The RNA virome of human and animal parasitic nematodes

Abstract

Screening published transcriptomes, we have discovered 75 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 these viruses are abundant in reproductive tissues of adult parasites, suggesting sexual/vertical transmission routes. 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 hosting these viruses have an intimate, chronic and life-long exposure to vertebrate tissues creating the opportunity to cross species barriers and so act as a novel paradigm for parasitic nematode diseases and a potential hidden reservoir of emerging viral diseases.

Cameroonian blackflies (Diptera: Simuliidae) harbour a plethora of (RNA) viruses

“…The flavivirus we found in the blackflies shows a dinucleotide profile suggestive of being an insect-specific virus and also the rhabdoviruses we found in the blackflies seem to be infecting invertebrates (see Figure 5B). Additionally, we added two other virus species recently identified in other studies to the Rhabdoviridae dinucleotide analysis: Onchocerca volvulus RNA virus 1 (OVRV1) is a rhabdovirus that was found in Onchocerca volvulus and elicits an immune response in the host (human as well as cattle and hamsters) (Quek et al . 2023), while Mundri virus was detected in a patient with nodding syndrome (Edridge et al .…”

“…In addition, another novel rhabdovirus, named OVRV1, was discovered by Quek et al . in public transcriptomes and viromes of Onchocerca volvulus nematodes (Quek et al . 2023).…”

“…2023). Because OVRV1 was shown to elicit an immune response in the vertebrate host of the nematode, it could potentially play a role in the pathogenesis of OAE (Quek et al . 2023).…”

“…Our dinucleotide analysis for the Rhabdoviridae , suggested that the viruses we found in the blackflies are invertebrate-specific viruses, in contrast to the previously identified rhabdoviruses MUNV (Edridge et al . 2022) and OVRV1 (Quek et al . 2023).…”

“…Additionally, we added two other virus species recently identified in other studies to the Rhabdoviridae dinucleotide analysis: Onchocerca volvulus RNA virus 1 (OVRV1) is a rhabdovirus that was found in Onchocerca volvulus and elicits an immune response in the host (human as well as cattle and hamsters) (Quek et al 2023), while Mundri virus was detected in a patient with nodding syndrome (Edridge et al 2022). Interestingly, both multiple OVRV1 variants as well as Mundri virus seem to cluster with vertebrate infecting rhabdoviruses, suggesting that these viruses may also be capable of infecting vertebrates.…”