CD4 and AIDS: This is most evident for HIV subtype D, which has been shown in multiple independent reports to be associated with more rapid CD4+ T-cell count decline and shorter time to AIDS than HIV subtypes A and B.[13–19] Research involving other subtypes has yielded less clear results, with some studies showing significant differences between subtypes,[16, 33] and others failing to do so.[25, 27, 34] However, three previous reports have associated CRF01_AE infection with unfavorable prognostic indicators when compared to other genotypes in co-circulation.