Year: 2013
Type: article
Abstract: Lentiviral restriction factors (RFs) are cellular proteins potently capable of blocking virus replication in vitro and delaying disease progression in vivo. Currently, five RFs (APOBEC3G, TRIM5α, Tetherin, SAMHD1, and Schlafen 11) are considered part of the intrinsic immune response to viral infection for their ability to block virus replication prior to activation of the innate immune system. Although RFs are constitutively expressed, it is unknown whether basal and early induction levels of these RFs are capable of limiting virus dissemination following mucosal challenge. We hypothesize that higher basal RF levels can exert a protective effect by delaying systemic infection. Real-time PCR analysis was conducted to analyze basal and post-exposure RF expression in the blood, lymph nodes and duodenum. Eight Indian-origin rhesus macaques received repetitive low dose rectal exposures of SIV/DeltaB670: 3 macaques became infected after 2 challenges (susceptible), 2 became infected after 3 challenges (intermediate), while two became infected after 6 challenges (resistant). One animal remained persistently uninfected despite 7 challenges (elite controller). Analysis of basal RF and Mx1 expression in the blood revealed animals resistant to infection had significantly higher TRIM5α and Mx1 expression than susceptible animals. Longitudinal analysis of RF and Mx1 expression in the blood revealed no RF induction in the resistant group, while the susceptible and intermediate groups experienced a 2 to 7-fold induction after virus appearance in the blood. Despite the lack of RF induction in the elite controller, a transient induction of Mx1 was evident after 2 of the 7 challenges, which may have provided further protection. Examination of RF induction in the gut revealed a similar pattern with expression mirroring that seen in the blood. Our results suggest that RFs are coordinately expressed in the blood and gut in response to infection and that levels remain unchanged, despite repeated exposure, until the animals become viremic. As such, induction of these RFs after virus exposure appears to be insufficient in containing virus dissemination. These results further suggest that basal RF levels in the blood may be used as a predictor for susceptibility to infection in macaques and possibly humans.
Author: Hadega Aamer
Language: English
Topic: HIV Research and Treatment
Subfield: Virology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W75992903