Zika virus shedding in the stool and infection through the anorectal mucosa in mice

Area of Science:

• Virology
• Immunology
• Pathogenesis

Background:

• Zika virus (ZIKV) poses global health concerns due to its unique biology and transmission.
• Human anal intercourse transmission of ZIKV is reported, but the anal route's infectivity and pathogenesis are unclear.

Purpose of the Study:

• To investigate ZIKV detectability in stool.
• To determine if ZIKV can infect hosts via the anal canal mucosa.
• To elucidate the pathogenesis of intra-anal ZIKV infection in a mouse model.

Main Methods:

• ZIKV RNA detection in stool from mouse models and a human patient.
• Intra-anal (i.a.) inoculation of ZIKV in Ifnar1^-/- and immunocompetent mice, including pregnant models.
• Analysis of viral replication, organ distribution, and immune responses.

Main Results:

• ZIKV RNA was recovered from stools in multiple mouse models and a ZIKV patient.
• i.a. ZIKV inoculation resulted in efficient infection, viremia, and replication in organs (brain, intestine, testes, rectum).
• Infection triggered robust immune responses and, in pregnant mice, transplacental infection and fetal developmental issues.

Conclusions:

• The anorectal mucosa is a potential site for ZIKV infection.
• Intra-anal ZIKV infection leads to systemic disease and impacts fetal development.
• These findings underscore the complexity of ZIKV transmission, particularly through anal intercourse.