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The Effects of Cycling on Drug Resistance HIV

Zidovudine and Didanosine are administered in cycles as a part of an HIV drug therapy. Both are Reverse Transcriptase Inhibitors (RTIs) that is, they inhibit the replication of the virus in the infected CD4+ T- cells. A mathematical model is formulated that incorporates four types of viruses: wild, resistant to Zidovudine, resistant to Didanosine and resistant to both. The lower bounds for drug efficacies are found by calculating the basic reproductive number assuming constant efficacies. A systematic study of drug therapy schemes via numerical simulations with emphasis on the dynamics of viral count as a function of drug resistance is performed. The results show that although there is no optimal schedule for switching of drugs, it is generally better to switch them within shorter time periods.

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Aaron Abromowitz, Harvey Mudd College
Andre Robinson, Medgar Evers College CUNY
Walter Chambliss, Alabama State University
Emmanuel J. Morales-Butler, Universidad Metropolitana
Anuj Mubayi, Arizona State University
Xiaohong Wang, Arizona State University
Abdessemad Tridane, Arizona State University