90-Second Read: Molecular evolutionary analysis of the current MV Hondius Andes virus outbreak

We analysed the S, M and L segment consensus sequences from the current MV Hondius-associated Andes virus outbreak available as of 17 May 2026. We downloaded Andes virus sequences for the S, M and L genome segments from ENA, Pathoplexus and GenBank, including eight outbreak-associated sequences available as of 17 May 2026 : PP_006WANE.2 ( WANE.2 ) was excluded because it was recently revoked from Pathoplexus. Manually reconstructed mutation tree of the eight available outbreak-associated Andes virus sequences as of 17 May 2026. As of 19 May 2026, the sampled outbreak diversity is compatible with PP_006WDKH.1 as the root of the current outbreak.

With the exception of the divergent XDHK.2 consensus, the currently available outbreak sequences differ by very few candidate mutations. PP_006W6RC.2 carries a T state at M:3500 and a nearby partially resolved insertion pattern also present in the closest non-outbreak comparator sequences. This date reflects the root of the currently sampled sequence diversity, not the start of the outbreak, as reported cases and symptom onsets predate the first available genome sequence. The previously divergent PP_006XDHK.2 sequence has been replaced by PP_006XDHK.4, which now clusters more closely with the other Canadian sequence, PP_006XDJH.4.

We thank all laboratories and researchers who generated and rapidly shared the sequence data that made this analysis possible. We also thank the Pathoplexus team for rapidly enabling Andes virus sequence sharing, and Dr David Safronetz and Dr Jonathan Audet for helpful discussions on the two Canadian sequences. This supports placing the root of the sampled outbreak close to the earliest available sequence, collected on 26 April 2026. Update since 17 May 2026: Since this analysis was performed, the Canadian consensus sequences have been updated on Pathoplexus.

Notably, in the updated sequences, XDJH.4 is no longer identical to the French sample, PP_006XBKH.1 : both Canadian sequences now carry three additional S segment differences at S:927, S:930, and S:1799. We note that a previous Virological post based on raw sequencing reads reported that the S and M segment outbreak sequences were identical and retained only two SNPs in the L segment as true differences among outbreak sequences. First, the earliest collected sample, WDKH.1, contains a G at M-segment reference position 51, corresponding to the candidate mutation M:G51A in other outbreak sequences.