Molecular evidence of HIV-1 transmission in a criminal case

Abstract

A gastroenterologist was convicted of attempted second-degree murder by injecting his former girlfriend with blood or blood-products obtained from an HIV type 1 (HIV-1)-infected patient under his care. Phylogenetic analyses of HIV-1 sequences were admitted and used as evidence in this case, representing the first use of phylogenetic analyses in a criminal court case in the United States. Phylogenetic analyses of HIV-1 reverse transcriptase and env DNA sequences isolated from the victim, the patient, and a local population sample of HIV-1-positive individuals showed the victim's HIV-1 sequences to be most closely related to and nested within a lineage comprised of the patient's HIV-1 sequences. This finding of paraphyly for the patient's sequences was consistent with the direction of transmission from the patient to the victim. Analysis of the victim's viral reverse transcriptase sequences revealed genotypes consistent with known mutations that confer resistance to AZT, similar to those genotypes found in the patient. A priori establishment of the patient and victim as a suspected transmission pair provided a clear hypothesis for phylogenetic testing. All phylogenetic models and both genes examined strongly supported the close relationship between the HIV-1 sequences of the patient and the victim. Resampling of blood from the suspected transmission pair and independent sequencing by different laboratories provided precaution against laboratory error.

Fig 1.

Phylogenetic analysis of the gp120 region using a minimum evolution criterion and maximum likelihood distances assuming an HKY+Γ model of evolution. Nucleotide alignment was based on the protein alignment in Fig. 3. P.ENV and V.ENV are DNA sequences for provirus PCR products from the patient and victim, respectively. Sequence names beginning with LA denote viral sequences from control HIV-1 infected individuals from the Lafayette, LA, metropolitan area. The same pattern of relationships (monophyly of all patient and victim sequences) was obtained with all phylogenetic methods (parsimony, minimum evolution, and Bayesian) and all models of evolution examined. In addition to the 100% bootstrap support of this relationship for the minimum evolution analyses, the parsimony bootstrap support and the Bayesian posterior support were also 100%.

Fig 2.

Phylogenetic analysis of the RT region; details of the analysis are the same as for Fig. 1. Nucleotide alignment was based on the protein alignment in Fig. 4. (a) Tree based on sequences from BCM. (b) Subtree of patient and victim sequences, including those added by MIC. In both a and b, the smaller set of boxed sequences represents the sequences from the victim, and the larger set of boxed sequences represents the patient plus victim sequences. The victim sequences were found to be embedded within the patient sequences in all analyses and for all models of evolution examined. In addition to the 100% bootstrap support of this relationship for the minimum evolution analyses, the parsimony bootstrap support was 96% and the Bayesian posterior support was 100%.