Rapid systemic spread and minimal immune responses following SIVsab intrarectal transmission in African green monkeys

Area of Science:

• Virology
• Immunology
• Primate Models of Infection

Background:

• African green monkeys (AGMs) are natural hosts of simian-immunodeficiency virus (SIV) and do not develop AIDS.
• Understanding early SIV infection events is crucial for comprehending pathogenesis in non-natural hosts.

Purpose of the Study:

• To investigate early SIV infection patterns in intrarectally inoculated AGMs.
• To understand viral establishment, dissemination, and disease progression dynamics.

Main Methods:

• 29 adult male AGMs were intrarectally inoculated with SIVsab92018 (SIVsab).
• Serial sacrifice throughout acute and early chronic infection phases.
• Ultrasensitive assays used to detect viral replication and viremia.

Main Results:

• Viral replication foci detected at inoculation site and draining lymphatics by 1-3 days post-infection (dpi).
• Rapid onset of viremia observed between 2-4 dpi.
• Systemic viral spread to all surveyed tissues; multiple transmitted/founder viruses identified, indicating a moderate mucosal genetic bottleneck.
• Resident CD4+ T cells were the initial target cells; no significant alteration in other immune cell populations at the entry site.

Conclusions:

• Intrarectal SIVsab infection in AGMs is characterized by swift viral dissemination.
• Lack of major target cell recruitment and no intervention window during the earliest infection stages.
• Findings are similar to intrarectal transmission but differ from vaginal transmission in macaques.