Monoclonal anti-dsRNA antibody-based metagenomics (MADAM) reveal Pyricularia oryzae mycovirome

Abstract

This study introduces MADAM (Monoclonal Anti-dsRNA Antibody-Based Metagenomics), a novel approach that integrates multiple technical modules previously used independently in other protocols. MADAM combines monoclonal antibody-mediated double-stranded RNA (dsRNA) enrichment, sequence-independent RT-PCR, and Oxford Nanopore Technologies (ONT) sequencing. Applied to Pyricularia oryzae , the causal agent of rice blast disease, MADAM enabled the comprehensive characterization of mycovirus genomes from four fungal isolates collected in Yunnan, China. The approach achieved high viral read recovery rates (46.9-72.7%) and identified 18 P. oryzae -associated RNA viruses spanning seven families: Botourmiaviridae , Deltaormycoviridae , Mymonaviridae , Partitiviridae , Polymycoviridae , Splipalmiviridae , and Ambiguiviridae . Seventeen nearly complete to complete viral genomes (1,226-6,085 nucleotides) were recovered, with sequence coverage ranging from 88% to 100%. Co-infections were detected in three of the four isolates, with notable discoveries including the first deltaormycovirus reported in P. oryzae , a putative novel member of Botourmiaviridae , and an additional genomic segment of a polymycovirus. MADAM successfully detected positive-sense, negative-sense ssRNA, and dsRNA viruses, demonstrating its broad applicability. By uncovering novel viruses and resolving complex co-infections, this method proves invaluable for fungal virology, with potential applications in diagnostics, surveillance, and biological control. Ultimately, MADAM advances our understanding of fungal viral diversity and paves the way for further exploration of mycovirus ecology and evolution.