AEGiS-11IAC: Comparison of HIV-1 sequences from 1981 with more current isolates in the United States epidemic.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Comparison of HIV-1 sequences from 1981 with more current isolates in the United States epidemic.

Int Conf AIDS 1996 Jul 7-12; 11:216 (abstract no. Tu.A.102)
Robbins KE, Jaffe HW, Schable CA, Brown TM, Rapier JM, Hoenes TE, Schochetman G, Kalish ML; Centers for Disease Control and Prevention, Atlanta, GA, USA. Fax: 404-639-2660. E-mail: Ker2@ciddas 1.em.cdc.gov.

OBJECTIVE: In 1981, specimens were obtained from homosexual men by the Centers for Disease Control(CDC) task force, formed to investigate increases in opportunistic infections among homosexual men in the U.S. We successfully used seven of these samples to determine the DNA sequences of two regions of the HIV-1 genome. These early sequences were compared with other U.S. subtype B sequences to aid in the understanding of the evolving genetic variability of HIV-1 in the United States.

METHODS: The date of collection of the samples was September to November of 1981, from patients residing in Georgia, New York, New Jersey and California. Both the p17 coding region of the gag gene and a 345 b.p. C2-V3 region of the env gene were sequenced directly from their PCR products by dye primer and dye terminator chemistries using an automated sequencer. Computer genetic analysis programs (MEGA, PHYLIP, GDE) were used to construct nucleotide and amino acid alignments, genetic distance matrices, and phylogenetic trees to compare these with U.S. subtype B sequences from the mid 1980's (Los Alamos HIV database) and 1995 (current CDC sequencing project).

RESULTS: Nucleotide genetic distance differences for the C2-V3 region were 5.2% (1981), 9% (mid 1980's), and 13.2% (1995). The p17 region also increased in divergence from 1981 (2.1%) to 1995 (5.3%). All strains in the amino acid alignment have the typical (North American) GPGR tetrapeptide at the tip of the V3 loop and none of the 1981 or 1995 sequences have the genotype associated with the more virulent, syncytium inducing phenotype. Phylogenetic analysis demonstrated shorter branch lengths for the 1981 sequences and no defined group clustering by date of collection.

CONCLUSIONS: The Los Alamos National Laboratory has estimated a 0.5-1%/yr. evolutionary rate of change for the V3 region of the env gene of HIV-1. The low interperson nucleotide divergence (5.2%) of these 1981 sequences is consistent with this rate and the recent nature of the HIV epidemic. The shorter branch lengths in the tree analysis indicate an earlier evolutionary origin from contemporary clade B sequences, yet the lack of early strain clustering needs to be explored further with additional sequences from this time period.

Keywords: AEGIS, HIV-1, Genes, env, Genes, gag, Disease Outbreaks, Polymerase Chain Reaction, United States, California, Georgia (Republic), Georgia, New York, New Jersey, Human, Male, genetics, ICA11

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