Variations found in the HIV-2 protease. Polymorphisms of the PR sequenced from 20 antiretroviral-naïve patients are compared to ROD and EHO strains (respectively subtypes A and B). X(bold): amino acid residue where variability was found in ARV-naïve patients. (N): number of samples from naïve patients harbouring the mutation. Red: mutations that were selected under ARV therapy in this study (Table 4).