Vaginal Challenge with an SIV-Based Dual Reporter System Reveals That Infection Can Occur throughout the Upper and Lower Female Reproductive Tract

Abstract

The majority of new HIV infections occur in women as a result of heterosexual intercourse, overcoming multiple innate barriers to infection within the mucosa. However, the avenues through which infection is established, and the nature of bottlenecks to transmission, have been the source of considerable investigation and contention. Using a high dose of a single round non-replicating SIV-based vector containing a novel dual reporter system, we determined the sites of infection by the inoculum using the rhesus macaque vaginal transmission model. Here we show that the entire female reproductive tract (FRT), including the vagina, ecto- and endocervix, along with ovaries and local draining lymph nodes can contain transduced cells only 48 hours after inoculation. The distribution of infection shows that virions quickly disseminate after exposure and can access target cells throughout the FRT, with an apparent preference for infection in squamous vaginal and ectocervical mucosa. JRFL enveloped virions infect diverse CD4 expressing cell types, with T cells resident throughout the FRT representing the primary target. These findings establish a new perspective that the entire FRT is susceptible and virus can reach as far as the ovary and local draining lymph nodes. Based on these findings, it is essential that protective mechanisms for prevention of HIV acquisition must be present at protective levels throughout the entire FRT to provide complete protection.

Th17 Cells Are Preferentially Infected Very Early after Vaginal Transmission of SIV in Macaques

“…We first examined CD3 expression in 4 animals where foci of infection were identified. Of 229 SIVmac239 infected cells characterized, 75.1% (172) of were CD3+, consistent with our previous study (Stieh et al, 2014). This indicates a significant portion of CD3 negative target cells (24.9%) including macrophages and dendritic cells (DCs) are infected during or shortly after transmission.…”

“…The 48-hour time point provides a “snapshot” into the state of SIV infection very early after challenge, before widespread systemic response to the virus. This time point was chosen as it was the earliest interval at which we could reliably detect reporter expression (Stieh et al, 2014). Reproductive tracts were removed, soaked in luciferin to reveal luciferase expression and sites of infection were detected using an in vivo imaging system (IVIS) as previously described (Stieh et al, 2014).…”

“…We have previously shown, through vaginal inoculation of RMs with a high titer SIV-based dual reporter vector (LICh) that expresses luciferase, that initial infection events can be widespread throughout the FRT and highly variable in their localization (Stieh et al, 2014). Using LICh as a guide gives us the ability to systematically identify and study small foci of infection events in situ 48 hours after viral challenge.…”

Bottlenecks in HIV-1 transmission: insights from the study of founder viruses

“…As with ‘treatment as prevention’, the anti viral agents must be present in sufficient concentration to eliminate all potential T/F viruses from establishing a sustained infection. Studies of non-human primates suggest that these target cells are at or near the genital mucosal surfaces 113 , but more distant cells throughout the female reproductive tract (including the ovaries) may be exposed to virus and infected 114 .…”

Characterization of the Influence of Semen-Derived Enhancer of Virus Infection on the Interaction of HIV-1 with Female Reproductive Tract Tissues

“…Using a unique method to identify distinct HIV-1 particles without the encumbrance of tissue autofluorescence, we demonstrated that HIV-1 can penetrate both the vaginal and ectocervical stratified squamous and endocervical simple columnar epithelia of the lower FRT (15). For a productive infection to occur, HIV-1 must efficiently traverse these epithelia to reach target cells (16)(17)(18) located in the intra-or subepithelial compartments (15,19). We took advantage of our ability to study the interaction of HIV-1 with mucosal sites to study the influence of SEVI on the diffusion of HIV-1 in FRT tissues.…”