A proposal for new criteria for the classification of hantaviruses, based on S and M segment protein sequences

Hantaviruses, members of the family Bunyaviridae, are the causative agents of hemorrhagic fever with renal syndrome and hantavirus cardiopulmonary syndrome. Hantaviruses are currently demarcated into species based on the guidelines provided by the International Committee on Taxonomy of Viruses (ICTV). These guidelines however, are often ignored by the descriptors of novel hantaviruses. With this study we attempted to refine the second ICTV guideline for hantavirus species demarcation by phylogenetically analyzing all in Genbank available complete sequences derived from the S, M or L segments of hantaviruses. S and M segment amino acid sequence comparison allowed clear and unequivocal distinction between different hantavirus species, and lead us to propose additional criteria for the demarcation of hantavirus species (S segment amino acid distance >10% or M segment amino acid distance >12%) and hantavirus groups (S segment amino distance >24% or M segment amino acid distance >32%). With this study, we propose to adjust the second rule of the ICTV classification guidelines ("a 7% difference in amino acid identity when comparing the complete S segment and M segment sequences") to a more appropriate rule, "a 10% difference in S segment similarity and a 12% difference in M segment similarity based on complete amino acid sequences" in accordance with the current situation in the hantavirus field.