Maxted, M. | Search bioRxiv

bioRxiv2022

EARLY AND MID-GESTATION ZIKA VIRUS (ZIKV) INFECTION IN THE OLIVE BABOON (PAPIO ANUBIS) LEADS TO FETAL CNS PATHOLOGY BY TERM GESTATION

Zika virus (ZIKV) infection in pregnancy can produce catastrophic teratogenic damage to the developing fetus including microcephaly and congenital Zika syndrome (CZS). We previously described fetal CNS pathology occurring by three weeks post-ZIKV infection in Olive baboons at mid-gestation, including neuroinflammation, loss of radial glia (RG), RG fibers, neuroprogenitor cells (NPCs) resulting in disrupted NPC migration. In the present study, we explored fetal brain pathologies at term gestation resulting from ZIKV infection during either first or second trimester in the Olive baboon. In all dams, viremia resolved after 7 days post infection (dpi). One first trimester infected dam aborted at 5 dpi. All dams developed IgM and IgG response to ZIKV with ZIKV IgG detected in fetal serum. Substantial placental pathology and inflammation was observed including disruption of syncytiotrophoblast layers, delayed villous maturation, partially or fully thrombosed vessels, calcium mineralization and fibrin deposits. In the uterus, ZIKV was detected in [3/4] first trimester but not in second trimester infected dams. While ZIKV was not detected in any fetal tissue at term, all fetuses exhibited varying degrees of neuropathology. Fetal brains from ZIKV infected dams exhibited a range of gross brain pathologies including irregularities of the major gyri and sulci of the cerebral cortex and cerebellar pathology. Frontal cortices of ZIKV fetuses showed a general disorganization of the six-layered cortex with degree of disorganization varying among the fetuses from the two groups. Frontal cortices from first but not second trimester infections exhibited increased microglia and astrocyte numbers (white matter) in both trimester infections. In the cerebellum, increased microglia were observed in both first and second trimester infected fetuses and decreased oligodendrocyte precursor cell populations in the cerebellar white matter in first trimester infections. In general, our observations are in accordance with those described in human ZIKV infected fetuses.

pathology↗

bioRxiv2020

MATERNAL ZIKA VIRUS (ZIKV) INFECTION FOLLOWING VAGINAL INOCULATION WITH ZIKV-INFECTED SEMEN IN THE TIMED-PREGNANT OLIVE BABOON

ZIKV infection is associated with pregnancy loss, fetal microcephaly and other malformations. While Aedes sp. 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 non-human primate (NHP) semen. It is critical to establish NHP models of vertical transfer of ZIKV that recapitulate human ZIKV 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). Timed pregnant baboons (n=6) were inoculated via vaginal deposition of baboon semen containing 106 ffu ZIKV (n=3, French Polynesian isolate:H/PF/2013, n=3 Puerto Rican isolate:PRVABC59) at mid-gestation (86-95 days gestation [dG]; term 183dG) on day (d) 0 (all dams), and then at 7 day intervals through three weeks. Maternal blood, saliva and cervico-vaginal washes were obtained at select days post-inoculation. Animals were euthanized at 28 days post initial inoculation (dpi; n=5) or 39 dpi (n=1) and maternal/fetal tissues collected. vRNA was quantified by qPCR. Viremia was achieved in 3/3 FP ZIKV infected dams and 2/3 PR ZIKV. ZIKV RNA was detected in cvw (5/6 dams;). ZIKV RNA was detected in lymph nodes, but not ovary, uterus, cervix or vagina in the FP ZIKV dams but was detected in uterus, vagina and lymph nodes. Placenta, amniotic fluid and all fetal tissues were ZIKV RNA negative in the FP infected dams whereas 2/3 PR 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 wide spread dissemination to tissues, including placenta compared to the FP strain. IMPORTANCEDue to its established link to pregnancy loss, microcephaly and other major congenital anomalies, Zika virus (ZIKV) remains a worldwide health threat. Although mosquitoes are the primary means of ZIVK transmission, sexual transmission in human populations is well documented and provides a means for widespread dissemination of the virus. Differences in viremia, tissue distribution, immune responses and pregnancy outcome from sexually transmitted ZIKV compared to the subcutaneous route of infection are needed to better clinically manage ZIKV in pregnancy. Through our previous work, we have developed the olive baboon as a non-human primate model of ZIKV infection that is permissible to ZIKV infection via the subcutaneous route of inoculation and transfer of ZIKV to the fetus in pregnancy. The current study evaluated the course of ZIKV infection after vaginal inoculation of ZIKV in pregnant baboons at mid-gestation using baboon semen as the carrier and comparing two isolates of ZIKV, the French Polynesian isolate first associated with microcephaly and the Puerto Rican isolate, associated with an increased risk of microcephaly observed in the Americas.

physiology↗