sˈʌbsᵻkwənt stˈʌdiz dˈɑːkjuːməntᵻd ðɪ ˈɪmpækt ʌv dɹˈʌɡ ɹᵻsˈɪstəns ˌɔn tɹˈiːtmənt fˈeɪlɪɹ, ðə pɹˈɛzəns ʌv mˈɪkstʃɚz ʌv dˈɪfɹənt vˈaɪɚɹəl fˈɛnətˌaɪps ænd dʒˈɛnətˌaɪps sˈɜːkjʊlˌeɪɾɪŋ ɪnðə sˈeɪm pˈeɪʃənt, ðə pɹˈiːɛɡzˈɪstəns ʌv dɹˈʌɡɹᵻsˈɪstənt mjˈuːtənts ɪn ʌntɹˈiːɾᵻd pˈeɪʃənts, ðɪ ˈɪmpækt ʌv dɪzˈiːz stˈeɪdʒ ænd vˈaɪɚɹəl ɹˌɛplɪkˈeɪʃən ɔnðə ɹˈeɪts ʌv vˈaɪɚɹəl ˌɛvəlˈuːʃən, ænd ðɪ ˌɪndᵻpˈɛndənt ˌɛvəlˈuːʃən ʌv dˈɪfɹənt pˌɑːpjʊlˈeɪʃənz ʌv ˌeɪtʃˌaɪvˈiː ɪn lˈɪmfɔɪd tˈɪʃuːz ænd ðə bɹˈeɪn.
Subsequent studies documented the impact of drug resistance on treatment failure, the presence of mixtures of different viral phenotypes and genotypes circulating in the same patient, the pre-existence of drug-resistant mutants in untreated patients, the impact of disease stage and viral replication on the rates of viral evolution, and the independent evolution of different populations of HIV in lymphoid tissues and the brain.