Phylogenetic Proximity
Definition
The principle in viral forensics that transmission between individuals is supported when their viral sequences cluster together in a phylogenetic tree separately from community strains, rather than being randomly distributed. Established as a forensic tool in the 1990 Florida HIV dental case.
- Signal used
- Clustering of viral sequences on a phylogenetic tree
- Supports
- Transmission link between individuals
- Landmark case
- 1990 Florida HIV dental case
- Field
- Viral/microbial forensics
Common questions
Why is clustering considered supportive rather than conclusive proof of transmission?+
Two people can carry closely related viral strains simply because those strains are common in their shared community, without any direct transmission between them. Analysts compare the pair against a broader set of community reference sequences to judge whether the clustering is distinctive enough to support a transmission link rather than coincidental shared background strains.
What made the 1990 Florida HIV dental case significant for this method?+
It was among the first uses of phylogenetic sequence comparison as evidence in a legal setting, showing that a patient's HIV strain clustered closely with the treating dentist's strain and with other infected patients, separately from unrelated community strains, supporting a common source.
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