Conserved marseilleviruses harboring diverse antibiotic resistance genes isolated from the Yangtze river Delta and the Pearl river delta, China.

Marseilleviruses are a group of double-stranded DNA viruses infecting Acanthamoeba within the phylum Nucleocytoviricota and are ubiquitous in water and soil globally. Here, we report six strains of marseilleviruses isolated from environmental samples in the Yangtze River Delta and the Pearl River Delta, China. Viral particles exhibited icosahedral shaped capsids measuring about 220 ~ 240 nm in diameter. Based on stability assays, viral particles were halotolerant and acid-tolerant, but sensitive to chloroform and high temperature. Genomics and phylogenetic analyses showed that these strains were highly conserved compared with other reported marseilleviruses. Diverse members of the small multidrug resistance (SMR) family of transporter, which is a type of antibiotics resistance gene (ARG) and contribute to the feature of antibiotic resistance in bacteria, to our best knowledge, are firstly described in Marseilleviridae. The alignments of primary structures and in-silico tertiary structures reveal structural and potential functional similarity between giant viral and bacterial SMR, suggesting a possible role in viruses' interaction with antibiotics. The biological properties of marseillevirus and the discovery of viral SMR provide insight in the external and intracellular environment fitness of these large amoeba-infecting viruses.