Andes virus analysis from the 2026 MV Hondius outbreak
This page presents a functional and phylogenetic analysis of the 2026 Andes virus genome sequences associated with the MV Hondius outbreak.
We applied Valthos's Cypress-1 model to analyze genome sequences from infected patients associated with the outbreak of a hantavirus (Andes virus) on the MV Hondius ship.
Our key findings are:
- Viral function scoring does not identify any mutations leading up to the 2026 outbreak strain that provide a high fitness advantage.
- Host compatibility scoring does not indicate this strain is substantially better adapted to humans than earlier related strains.
- Cypress-1 scoring: We use our specialized protein language model, Cypress-1, which was adapted to biodefense workflows, to evaluate the functional consequences of the outbreak strain's mutations on both viral function and host compatibility.
- Reference comparison: To contextualize the model's scores, we compare them against related Andes virus sequences, including two Argentine human isolates from 2018, a human isolate from the 2018 Epuyén outbreak, and the official reference sequence (RefSeq; Chile 1997).
- Phylogenetics: We map the genome's sequences onto species-wide phylogenetic trees (one per segment). The 2026 outbreak sequences cluster closely with Argentine human isolate sequences from 2018.
- Note: Cypress-1 scores are experimental and should be interpreted with caution while validation continues.
2026 outbreak sequences were accessed through Pathoplexus. Accession numbers and original sequence links are included below. We thank the submitting groups for sharing these data.