Sexual transmission of hepatitis E virus via vaginal and rectal routes in a rabbit model

Hepatitis E virus (HEV) is a major cause of acute hepatitis worldwide. While faecal-oral transmission is well-established, the potential for sexual transmission remains unclear. This study aimed to investigate whether HEV can be transmitted through sexual routes using a rabbit model. A total of 80 rabbits were inoculated intravaginally or intrarectally with HEV, compared to intravenous challenge. To assess hormonal influence, rabbits were pre-treated with medroxyprogesterone acetate (MPA) or pregnant mare serum gonadotrophin (PMSG) prior to vaginal inoculation. Also, 12 pregnant rabbits were injected with HEV by vaginal and intravenous routes, respectively, to evaluate adverse outcomes. Viral shedding, seroconversion, viral loads in tissues, histopathology and vaginal microbiota were analysed. Our results showed that HEV can be transmitted through both vaginal and rectal routes, establishing productive but less efficient infections than intravenous inoculation. Crucially, the MPA dramatically enhanced vaginal susceptibility, leading to prolonged viral shedding, higher systemic viral loads and 100% seroconversion, compared to partial infection in PMSG-treated and untreated controls. Vaginal infection in pregnant rabbits resulted in significant adverse outcomes, including abortion (66.7%) and vertical transmission. Furthermore, vaginal inoculation altered the local microbiota and transcriptome, suggesting a remodelled genital tract microenvironment. Our study provided the first direct experimental evidence that HEV can be sexually transmitted via vaginal and rectal routes. The progesterone-mediated enhancement of susceptibility and the severe pregnancy outcomes highlighted its public health risk, particularly for women.