Maternal Zika Virus (ZIKV) Infection following Vaginal Inoculation with ZIKV-Infected Semen in Timed-Pregnant Olive Baboons

Abstract

Zika virus (ZIKV) infection is now firmly linked to congenital Zika syndrome (CZS), including fetal microcephaly. While Aedes species of mosquito are the primary vector for ZIKV, sexual transmission of ZIKV is a significant route of infection. ZIKV has been documented in human, mouse, and nonhuman primate (NHP) semen. It is critical to establish NHP models of the vertical transfer of ZIKV that recapitulate human pathogenesis. We hypothesized that vaginal deposition of ZIKV-infected baboon semen would lead to maternal infection and vertical transfer in the olive baboon (Papio anubis). Epidemiological studies suggest an increased rate of CZS in the Americas compared to the original link to CZS in French Polynesia; therefore, we also compared the French Polynesian (FP) ZIKV isolate to the Puerto Rican (PR) isolate. Timed-pregnant baboons (n = 6) were inoculated via vaginal deposition of baboon semen containing 106 focus-forming units (FFU) of ZIKV (n = 3 for FP isolate H/PF/2013; n = 3 for PR isolate PRVABC59) at midgestation (86 to 95 days of gestation [dG]; term, 183 dG) on day 0 (all dams) and then at 7-day intervals through 3 weeks. Maternal blood, saliva, and cervicovaginal wash (CVW) samples were obtained. Animals were euthanized at 28 days (n = 5) or 39 days (n = 1) after the initial inoculation, and maternal/fetal tissues were collected. Viremia was achieved in 3/3 FP ZIKV-infected dams and 2/3 PR ZIKV-infected dams. ZIKV RNA was detected in CVW samples of 5/6 dams. ZIKV RNA was detected in lymph nodes but not the ovaries, uterus, cervix, or vagina in FP isolate-infected dams. ZIKV RNA was detected in lymph nodes (3/3), uterus (2/3), and vagina (2/3) in PR isolate-infected dams. Placenta, amniotic fluid, and fetal tissues were ZIKV RNA negative in the FP isolate-infected dams, whereas 2/3 PR isolate-infected dam placentas were ZIKV RNA positive. We conclude that ZIKV-infected semen is a means of ZIKV transmission during pregnancy in primates. The PR isolate appeared more capable of widespread dissemination to tissues, including reproductive tissues and placenta, than the FP isolate. IMPORTANCE Zika virus remains a worldwide health threat, with outbreaks still occurring in the Americas. While mosquitos are the primary vector for the spread of the virus, sexual transmission of Zika virus is also a significant means of infection, especially in terms of passage from an infected to an uninfected partner. While sexual transmission has been documented in humans, and male-to-female transmission has been reported in mice, ours is the first study in nonhuman primates to demonstrate infection via vaginal deposition of Zika virus-infected semen. The latter is important since a recent publication indicated that human semen inhibited, in a laboratory setting, Zika virus infection of reproductive tissues. We also found that compared to the French Polynesian isolate, the Puerto Rican Zika virus isolate led to greater spread throughout the body, particularly in reproductive tissues. The American isolates of Zika virus appear to have acquired mutations that increase their efficacy.

Early Embryonic Loss Following Intravaginal Zika Virus Challenge in Rhesus Macaques

“…Previous studies in nonpregnant NHP have shown that intravaginal ZIKV inoculation results in successful infection after a single challenge approximately 33-75 percent of the time ( 31 , 37 , 59 ). In pregnant olive baboons, a single intravaginal inoculation mid-gestation with semen containing ZIKV (originating from French Polynesia or Puerto Rico) resulted in 4 of 6 animals developing detectable vRNA in blood, with an additional animal having detectable vRNA in blood after a second inoculation ( 33 ). This was the rationale for the choice to perform repeat challenges at two-hour intervals in this study: in order to maximize the likelihood of establishing a productive infection in our small cohort within a single day.…”

Sexual Transmission of Arboviruses: A Systematic Review

“…TBEV and ZIKV have been transmitted between laboratory mice by natural mating and SPONV RNA has been detected in the semen of infected mice [90,93,96,134]. Arboviruses detected in the reproductive tract and/or in sexual fluids of NHPs include CCHFV and ZIKV [24,[115][116][117][118][119][120][121][122][123]. Several arboviruses have also been detected in the reproductive tract or sexual fluids of livestock, including AKAV, BEFV, BTV, EHDV, JEV and SBV [37,42,132,143,156,157].…”

“…In one study, ZIKV RNA was detected at high levels in the semen of male NHPs, remaining detectable for 28 days, with viral RNA also present but at lower levels in vaginal secretions of female NHPs [115]. ZIKV has been detected throughout the reproductive tracts of infected male and female NHPs [115,116,[118][119][120][121][122][123]. ZIKV RNA was detected in the testes and epididymis of male olive baboons for up to 10 and 41 days after infection [116].…”

Chloroquine and Sulfadoxine Derivatives Inhibit ZIKV Replication in Cervical Cells

“…Corroborating this, a prospective case study of a Brazilian woman demonstrated the presence of the antigen and viral genome in the vagina and endocervical samples up to the 31st day of Zika onset symptoms [ 13 ]. The high permissiveness of reproductive tract cells to ZIKV in-vitro infection has also been demonstrated [ 14 , 15 , 16 ]; studies in different experimental models have also pointed to the relevance of vaginal mucosa cells for ZIKV infection [ 17 , 18 , 19 , 20 ]. These data have demonstrated that infected semen in vaginal and endocervical mucosa can contribute strongly to the sexual transmission cycle and complications caused by ZIKV infection, such as male infertility and, especially, those associated with pregnant women [ 5 , 21 , 22 ].…”