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Being Alive
MEDICAL UPDATE: SI Strains of HIV and AZT Therapy
presented by Mark Katz, MD and reported by Jim Stoecker
November 5, 1993
Being Alive 1993 Nov 5: 6

We know that there are numerous strains of HIV. An infected person may harbor several strains, and these strains can evolve or mutate over time. One of the most damaging strains of HIV is termed syncytia-inducing; these SI strains of the virus can cause rapid destruction of the immune system.

Dutch researchers, reporting in the Journal of Infectious Diseases (September 1993), looked at data on a group of 52 people. They compared those treated with AZT to those treated with a placebo over a two year period. These researchers found that there was a marked difference in the efficacy of AZT, depending on the presence of SI strains.

In people harboring SI strains of HIV, disease progression occurred whether on AZT or placebo. Further, AZT did not prevent the occurrence of SI strains; these strains were as likely to be found in those on AZT as those on placebo.

This study may offer one explanation why AZT is not useful to all who take it. It may be that only those without SI strains of HIV can benefit from this antiviral. The problem is, of course, that there is no commercially available test for identifying viral strains. If such a test were available, medical providers might be better able to develop an effective course of antiviral therapy for the individual.