Table 1. Similarities and differences between well-adapted natural SIV hosts and poorly adapted recent or experimental HIV and SIV hosts.
| Well-adapted natural SIV hosts (sooty mangabeys and African green monkeys) |
Nonadapted recent or experimental hosts (humans and Asian macaques) |
|---|---|
| Acute infection | Acute infection |
| Virus replication peaks within a few weeks from infection. | Virus replication peaks within a few weeks from infection. |
| Post-peak decline of viral load indicates partial control of virus replication. | Post-peak decline of viral load indicates partial control of virus replication. |
| Elevated innate and adaptive immune response to the virus. | Elevated innate and adaptive immune response to the virus. |
| Marked type I interferon response. | Marked type I interferon response. |
| Variable levels of bystander T cell activation and apoptosis. | High levels of bystander T cell activation and apoptosis. |
| Establishment of an anti-inflammatory milieu. | Depletion of mucosal CD4+ T cells. |
| Depletion of mucosal CD4+ T cells. | |
| Chronic infection | Chronic infection |
| High set point of virus replication that persists despite the host immune response. | High set point of virus replication that persists despite the host immune response. |
| Virus replication mostly occurring in short-lived, activated CD4+ T cells. | Virus replication mostly occurring in short-lived, activated CD4+ T cells. |
| Healthy CD4+ T cell counts in most animals. No progressive depletion of mucosal CD4+ T cells. | Progressive depletion of circulating and mucosal CD4+ T cells. |
| Resolution of type I interferon responses. | Persistent type I interferon responses. |
| Limited immune activation and T cell apoptosis. | Generalized immune activation and significant T cell apoptosis. |
| Preservation of mucosal TH17 cells. | Preferential loss of mucosal TH17 cells. |
| Absence of microbial translocation. | Microbial translocation is prominent. |
| Clinical outcome | Clinical outcome |
| Progression to AIDS is very rare. | Progression to AIDS occurs in most cases. |
| Vertical transmission is rare. | Vertical transmission is more common. |