Summary auto-generated
Researchers studied simian immunodeficiency virus (SIV) infection in 11 rhesus macaques to understand rapid disease progression. Virus-binding serum antibody levels measured at 7 and 13 weeks post-infection strongly predicted disease outcome (P < 0.005). Animals with low antibody responses progressed to AIDS-like disease within 3-5 months, while those with high antibody responses remained healthy after one year. The study revealed that acute depletion of CD20+ B cells during early infection correlated with poor antibody responses and rapid progression. About 20-30% of infected animals showed low or undetectable antibody responses and rapid clinical decline. Analysis of CD4+ T cells, CD8+ T cells, viral load, and neutralizing antibodies showed that virus-binding antibody titer at 13 weeks was the single best predictor of survival. Western blot analysis indicated rapid progressors produced weak responses to viral proteins, while slow progressors mounted diverse antibody responses to multiple viral antigens. The findings suggest that acute viral replication and lymphocyte destruction during early infection establish a viral set point that determines subsequent disease progression rates.
Key findings
- SIV-binding serum antibody titers at 7-13 weeks post-infection strongly predicted disease progression and survival (P < 0.005), with high antibody responders surviving longer than one year while low responders progressed to AIDS within 3-5 months
- Rapid progressors showed acute depletion of CD20+ B cells, with B cell counts declining to approximately 50% of pre-infection values by 13 weeks, directly correlating with inability to mount antibody responses
- Approximately 20-30% of infected macaques became rapid progressors with low or undetectable antibody responses and concurrent high viral loads, suggesting early immune damage determines disease outcome
- Animals with early and sustained antibody responses produced diverse antibodies to multiple viral proteins (Gag and Env), while rapid progressors mounted weak responses to limited viral antigens
- The study identified 6-7 weeks post-infection as a critical 'set point' when early immune markers became predictive of long-term survival, enabling improved experimental design for future SIV/HIV studies
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Abstract
Clinical and laboratory markers of simian immunodeficiency virus (SIV) infection were studied during the first 3 months after intravenous inoculation of rhesus macaques. Virus-binding serum antibody titres were correlated strongly with disease progression (P < 0.005) and were predictive of disease outcome by 7 weeks after inoculation. Low virus- binding serum antibody responses to SIV occurred in animals that also showed acute depletion of circulating CD20+ B cells. Acute damage to the CD4+ T cell and CD20+ B cell populations rendered some animals incapable of mounting virus-specific antibody responses and these macaques became the rapidly progressing cases comprising approximately 20-30% of infected animal cohorts.