Chronic innate immune impairment and ZIKV persistence in the gastrointestinal tract during SIV infection in pigtail macaques.

Mosquito borne flaviviruses, including dengue (DENV) and Zika (ZIKV) viruses, have caused global epidemics in areas with high HIV prevalence due to the expanded geographic range of arthropod vectors. Despite the occurrence of large flavivirus outbreaks in countries with high HIV prevalence, there is little knowledge regarding the effects of flavivirus infection in people living with HIV (PLWH). Here, we use a pigtail macaque model of HIV/AIDS to investigate the impact of simian immunodeficiency virus (SIV)-induced immunosuppression on ZIKV replication and pathogenesis. Early acute SIV infection induced expansion of peripheral ZIKV cellular targets and increased innate immune activation and peripheral blood mononuclear cells (PBMC) from SIV infected macaques were less permissive to ZIKV infection . In SIV-ZIKV co-infected animals, we found increased persistence of ZIKV in the periphery and tissues corresponding to alterations in innate cellular (monocytes, neutrophils) recruitment to the blood and tissues, decreased anti-ZIKV immunity, and chronic peripheral inflammatory and innate immune gene expression. Collectively, these findings suggest that untreated SIV infection may impair cellular innate responses and create an environment of chronic immune activation that promotes prolonged ZIKV viremia and persistence in the gastrointestinal tract. These results suggest that PLWH or other immunocompromised individuals could be at a higher risk for chronic ZIKV replication, which in turn could increase the timeframe of ZIKV transmission. Thus, PLWH are important populations to target during the deployment of vaccine and treatment strategies against ZIKV.