Table 2.
Features of the HIV-1 Pandemic, According to Subtype or Circulating Recombinant Form (CRF).*
| Subtype or CRF | Location | Global Prevalence | Tropism and Replication | Disease Progression | Response to Therapy |
|---|---|---|---|---|---|
| Subtype | |||||
| A | East and Central Africa, Central Asia, Eastern Europe | 12.3% | Mostly uses CCR5, even in late infection40 | NA | No significant difference as compared with C and D41 |
| B | Americas, Western Europe, East Asia, Oceania | 10.2% | Uses CCR5 early, with increasing use of CXCR4 in late infection28 | HLA-B7 associated with poor CTL response and increased viremia42,43; HLA-B57 associated with slow progression42; B strain in Brazil associated with slow progression44 | NA |
| C | India, Eastern and Southern Africa | 49.9% | Mostly uses CCR5, even in late infection28; increased vaginal shedding30 and mother-to-child transmission29,45 | HLA-B57 associated with slow progression42 | No significant difference as compared with A and D41; differential pathways to resistance46–49 |
| D | East Africa | 2.5% | Uses CXCR4 in early infection27 | Progression more rapid than A in Uganda, Kenya, and Tanzania37–39 | NA |
| G | West Africa | 6.3% | NA | NA | NA |
| F, H, J, and K | Various | Each <1.0% | NA | NA | NA |
| CRF | |||||
| CRF01_AE | Southeast Asia | 4.7% | May have higher initial viral load than B but subtype may be a confounder50 | Possibly accelerated progression as compared with B36 | NA |
| CRF02_AG | West Africa | 4.8% | Higher rate of replication in vitro than B51 | NA | NA |
| Other | Various | Each <0.1% | NA | NA | NA |
*
Location and prevalence data are from Hemelaar et al.10 Other CRFs include CRF03 through CRF43, and this category is expanding. CTL denotes cytotoxic T lymphocyte, and NA not available.