Superinfection Seen in Case of Multidrug-resistant Primary HIV Infection

By Megan Rauscher

In the August 20th issue of AIDS, Canadian clinicians report what they believe is the first documented case of an individual with multidrug resistant (MDR) primary HIV-1 infection who was apparently infected with a second MDR strain of the virus.

The patient in question apparently cleared the original infection. "In spite of a rapid decline in plasma viremia suggestive of an effective immune response, this patient was susceptible to a second infection," Dr. Mark A. Wainberg and colleagues from McGill AIDS Centre in Montreal point out.

"From a public health standpoint, this is not trivial," Dr. Wainberg told Reuters Health, in that it challenges the assumption that an immune response protects against re-infection.

The case came to light in a study in which the team evaluated genotypic changes in circulating viral quasi-species over a period of 1.5 to 7 years in 31 patients enrolled in a primary HIV-1 infection study.

Patients infected with wild-type (n=15), resistant (n=10), and MDR infections (n=6) displayed "little quasi-species evolution (>99.6% homology) for more than 1.5 years, regardless of the route of transmission," the team reports.

Transmitted resistant or MDR mutations, except for mutation 184V, persisted for 2 to 7 years following primary HIV-1 infection.

Because of the lack of reversion of MDR strains to wild-type strains, the authors surmise that archival wild-type virus may be absent from MDR infections acquired as primary infections.

As mentioned, one patient who acquired an MDR HIV-1 primary infection from one partner and subsequently cleared the virus became re-infected with a second heterologous MDR strain from a different partner. Phylogenetic and clonal analysis of isolates from both partners confirmed the MDR superinfection in this individual.

The investigators believe the observed 13-fold reduction in viral fitness of the initial MDR strain (relative to the wild-type strain isolated from the source partner following a treatment interruption) may have played a role in the superinfection.

Summing up, Dr. Wainberg said: "One of the salient points of our article is that superinfection with other strains of HIV can occur - a person may become doubly infected by different partners."

Another, he added, is that "drug-resistant viruses that cause new HIV infection can persist over months and even years even when the newly-infected patient does not receive treatment."

This "raises serious issues regarding HIV-1 management," Dr. Wainberg and colleagues write. "For newly infected MDR patients, drug resistance analysis and viral fitness may provide useful information in regard to ultimate therapeutic strategies," they add.

8/27/04

AIDS 2004;18:1653-1660.