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Superinfection can confer HIV drug resistance
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NEW YORK (Reuters Health, Sept 19, 2005) - HIV drug resistance can be acquired through superinfection with another strain of HIV, researchers in California report.
"Superinfection does occur, and it can have devastating clinical implications, including the acquisition of drug resistant HIV and probably faster disease progression," Dr. Davey M. Smith from University of California San Diego, told Reuters Health.
Dr. Smith and colleagues describe the case of a patient infected with a drug-sensitive strain of HIV who was later superinfected with another strain resistant to protease inhibitors.
Initial testing of the HIV infecting the patient showed no drug resistance, the authors report in the August 12th issue of AIDS. Nearly 9 months after the initial infection, the patient's HIV load suddenly began to increase, reaching levels 50 times higher within 4 months, the report indicates. Testing 5 months later revealed resistance to protease inhibitors, the researchers note, even though the patient had not been treated with protease inhibitors.
Subsequent testing demonstrated that the patient had been infected with two distinct strains of HIV. The replication capacity of the superinfecting virus was only one third that of the first HIV strain, consistence with the presence of protease and M184V mutations.
"The greater fitness of the second virus in this individual, demonstrated by its predominance in vivo, was not supported by the replication capacity assay of the viral isolates," the investigators explain.
"The replication capacity assay only interrogates (or assesses) replication fitness contributed by the pol coding region, while other genes such as env most likely play an important role in determining in vivo fitness of the virus."
This patient's superinfection was likely acquired during his persistent engagement in unprotected receptive anal intercourse with partners of unknown HIV serostatus, the report indicates.
"Clinicians must continue to address continuing HIV exposures by individuals who are already infected with HIV," Dr. Smith said. "I suspect that DRATS (Drug Resistance Acquired through Superinfection) occurs more often than we think."
"One of the best things we can do clinically is to do resistance testing prior to starting initial therapy. This would hopefully pick up transmitted drug resistance that might have occurred either from the initial infection or from superinfection."
FULL REPORT
HIV drug resistance acquired through superinfection
http://www.natap.org/2005/HIV/080105_01.htm
.....he had an incomplete response to therapy most likely because the superinfecting viral strain had a decreased susceptibility to two of the prescribed medications.....
AIDS August 2005
A Case of Superinfection
http://www.natap.org/2005/HIV/090205_06.htm
"In-Depth Analysis of a Heterosexually Acquired HIV-1 Superinfection: Evolution, Temporal Fluctuation, and Intercompartment Dynamics from the Seronegative Window Period through 30 Months Postinfection"
Journal of Virology
September 2005
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