HIV/AIDS: HIV-1 Strain and Drug Resistance

HIV strain (subtype) variation is part of the changing nature of the HIV epidemic in Canada. It is important to expand the collection and analysis of data related to subtype surveillance across the country in order to better understand and respond to changes in the HIV epidemic.  In addition to subtype variation, it is also important to understand how mutations in HIV can cause resistance to antiretroviral medications.  Resistance to these medications can seriously influence the decisions made regarding treatment strategies.

To better understand these issues, the Public Health Agency of Canada has created the Canadian HIV Strain and Drug Resistance Surveillance Program (SDRP).  As part of this program, Field Surveillance Officers in participating provinces coordinate the submission of epidemiologic data and serum samples to the Public Health Agency of Canada.

At the National Laboratory for HIV Genetics, the specimens are analysed for information on the HIV virus, including the subtype of the virus that is responsible for the infection.  They also look for any genetic mutations present that would be responsible for drug resistance.

The National Laboratory for HIV Reference Services perform tests on the specimens to estimate the time of infection as either recent or not.  To test for this, the lab uses a ‘sensitive/less sensitive’ testing method known as STAHRS (the Serologic Testing Algorithm for Recent HIV Seroconvertors).  This test is also called the detuned assay.

All of this data is analysed and used to guide policies on HIV treatment and prevention programs. It is also used to produce the report titled "HIV-1 Strain and Primary Drug Resistance in Canada". The most recent report contains data to March 31, 2005.