Molecular characterization of the genome of a new bunyavirus isolated in 2023 in Huzhou, China

The novel bunyavirus (SFTSV) causes severe fever with thrombocytopenia syndrome (SFTS), which has a high mortality rate and poses a serious threat to public health. To investigate the genomic characteristics of SFTSV strains isolated in Huzhou, China, in 2023, we sequenced SFTSV isolates and constructed a phylogenetic tree, and analyzed their homologies, average genetic distances, and amino acid (aa) mutations using DNAstar and MEGA software. The two SFTSV strains belonged to genotypes A and D. The nucleotide (nt) and aa sequence similarities of the two strains were 96.61% and 98.64%, respectively. The nt and aa sequence homologies with human reference strains of the same genotypes were 94.44% and 97.28%, respectively. The nt and aa sequence homologies with syngeneic tick host reference strains were 94.56% and 97.96%, respectively. The two SFTSV isolates had different mutation rates in the L, M, and S proteins; the M protein exhibited the highest mutation rate. Further investigations of SFTSV are warranted to explore the distributions of its genotypes, as well as its nt and aa mutations.