Why are the 333E/D mutations not listed in HIVResistanceWeb's NRTI charts?
Dr. Robert Shafer responds: G333E is a polymorphism that has been reported in 4/70 (6%) untreated persons and 26/212 (12%) of persons receiving NRTIs [Gallego'01].
G333E has been reported to facilitate zidovudine resistance in isolates from patients receiving zidovudine and lamivudine who also have multiple NEMs [Kemp'98]. However, dual resistance to these drugs usually emerges without this change [Shafer'98, Masquelier'99].
There are no data suggesting that this mutation by itself reduces zidovudine susceptibility.
