Summary auto-generated
This study investigated whether beta-chemokine production by CD8+ T cells correlates with protection against simian immunodeficiency virus (SIV) challenge in macaques vaccinated with live attenuated SIVmacC8. Six cynomolgus macaques were vaccinated and later challenged with infectious SIVsm virus. Three animals showed complete protection, one showed partial protection, and two became infected. CD8+ cell culture supernatants from completely or partially protected monkeys demonstrated higher anti-viral suppressive activity (45-55% inhibition) compared to infected animals (9-33% inhibition). Notably, protected macaques produced significantly higher levels of three beta-chemokines—RANTES, MIP-1α, and MIP-1β—both before and after vaccination compared to animals that became infected. Interestingly, baseline chemokine production before vaccination was higher in animals that would later resist challenge, suggesting genetic or environmental factors influence chemokine production capacity. While beta-chemokines appear important for protection, they alone were insufficient to protect naive macaques, indicating that specific immune responses and chemokines work synergistically. The findings suggest beta-chemokine induction should be considered in future HIV vaccine development strategies.
Key findings
- Protected macaques produced significantly higher levels of beta-chemokines (RANTES, MIP-1α, MIP-1β) compared to infected animals, with suppression of SIV replication correlating with chemokine levels
- Animals that resisted SIV challenge showed higher CD8+ T cell anti-viral suppressor activity (45-55% inhibition) compared to infected animals (9-33% inhibition)
- High baseline beta-chemokine production existed before vaccination in animals that would later resist challenge, suggesting genetic or environmental predisposition independent of vaccination
- Beta-chemokines alone were insufficient for protection; synergy with specific immune responses was required, as naive macaques with high chemokine levels remained susceptible to SIV challenge
- Live attenuated SIVmacC8 vaccination induced transient increased MIP-1β production at 2-3 weeks post-immunization in all vaccinated animals
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Abstract
Simian immunodeficiency virus (SIV) uses the CCR5 chemokine receptor as the main co-receptor to enter CD4(+) cells. RANTES, MIP-1alpha and MIP-1beta have been suggested as the major human immunodeficiency virus-suppressor factors produced by CD8(+) T-cells. The aim of this study was to investigate the CD8(+) T-cell production of anti-viral factors and of beta-chemokines in six cynomolgus macaques vaccinated with live attenuated SIVmacC8 in relation to protection against infectious intrarectal SIVsm challenge. Three of the vaccinated animals were completely protected and one was partially protected against the challenge virus. Interestingly, these monkeys showed higher in vitro anti-viral CD8(+) cell suppressor activity and beta-chemokine production both before and after vaccination as compared to the infected monkeys. The results indicate that beta-chemokines may play a role in protective immunity but also that genetic and/or environmental factors may influence their production.