4. Taxonomy and distribution of hantaviruses
The Hantaviridae Study Group of the International Committee on Taxonomy of Viruses (ICTV) designated the method DEmARC for classifying the new hantavirus genera and species. DEmARC uses the phylogenetic relationships and pairwise evolutionary distances (PED) values of the concatenated S and M segment sequences, calculated with the maximum likelihood method and the Whelan and Goldman (WAG) substitution model. The PED cutoff value of 0.1 is used for species demarcation inHantaviridae .39
In 2018, only one virus genus (orthohantavirus ) was classified inHantaviridae . In 2019, three new virus genera (Loanvirus ,Mobatvirus , and Thottimvirus ) in Hantaviridae were classified. In 2023, four subfamilies (Actantavirinae ,Agantavirinae , Mammantavirinae , andRepantavirinae ), seven genera (Actinovirus ,Agnathovirus , Loanvirus , Mobatvirus ,Orthohantavirus , Thottimvirus , and Reptillovirus ), and 54 species in Hantaviridae were classified (TableS1 ) (Figure 3 ).40,41 Robina virus which was reported in Australia in 2017, may belong to theMobatvirus genus and needs to be reclassified (Figure3 ).42 These taxa were consistent with the phylogenetic relationships in their RdRp genes (Figure3 ),43 and they are largely consistent with their host distribution and conserved sequences at the genome termini.39 The ICTV Hantaviridae Study Group will reclassify in 2023−2024 and only evaluate those viruses with complete genome sequences.44
The genus Actinovirus covers five species of fish viruses, with four identified in China in 2018 and one identified in Europe in 2020.45 The genus Agnathovirus covers one species of fish virus identified in China in 2018.45The genus Loanvirus covers two species of bat viruses identified in China in 2013 and Czech Republic in 2015, respectively.46,47 The genus Mobatvirus covers three species of bat virus identified in Vietnam, China, and Philippines, respectively, in 2015−2016,48-50 besides one mole virus identified in Poland in 2014 and one shrew virus identified in Russia in 2019.51,52 The genusOrthohantavirus covers 38 species with hosts in rodents, moles, shrews, and humans.40 As mentioned above, HTNV, SEOV, DOBV, PUUV, SNV, and ANDV are widely distributed and highly pathogenic to humans.2 The genus Thottimvirus covers two species of shrew viruses identified in India in 2007 and in Japan in 2008.53,54 The genus Reptillovirus covers one species of gecko virus identified in China in 2018.45
Some species of hantaviruses have been classified into several lineages. For example, the HTNVs isolated from China were classified into 10 lineagesas per their S or M genomic segment sequences.55 SEOVs were classified into six lineages (1−6) as per their M genomic segment sequences. Lineages 1, 2, 3, and 5 of SEOVs were isolated from China, while lineage 4 included isolates from China, South Korea, Japan, Singapore, Vietnam, and the USA. Lineage 6 SEOVs were isolated from the UK except for one strain from Brazil.56