We will examine ZIKV tissue tropism and the duration of ZIKV RNA detection in maternal tissues at three time points following first trimester ZIKV infection: 30, 65 and 105 days post-infection. This specific study, ZIKV-019, will examine ZIKV tissue tropism and the duration of ZIKV RNA detection at 65 days post-infection. We will also examine ZIKV tissue tropism in fetal tissues at the same time points.
Pregnant Indian-origin rhesus macaques will be challenged subcutaneously at day 45 of gestation with 10E4 PFU ZIKV Puerto Rico (PRVABC59). Plasma, urine and saliva viral loads will be measured frequently immediately following infection, then weekly until pregnancy termination. CSF viral loads will be measured twice during pregnancy. Amniotic fluid viral loads will be measured every other week. The dam will undergo necropsy at 65 days post-ZIKV infection and multiple tissues will be evaluated for ZIKV RNA and infectious virus. Fetal tissues will also be evaluated for ZIKV RNA and infectious virus.
- 527453 challenged with 10E4 PFU ZIKV Puerto Rico (PRVABC59) on 12.27.16
- 291635 Fetus of 527453
- 146523 challenged with 10E4 PFU ZIKV Puerto Rico (PRVABC59) on 09.22.17
- 243862 fetus of 146523
- 858972 challenged with 10E4 PFU ZIKV Puerto Rico (PRVABC59) 10.06.17
- 350845 fetus of 858972
- 419969 is scheduled to be challenged with 10E4 PFU ZIKV Puerto Rico (PRVABC59) on December 1st 2017.
- 121638 fetus of 419969.
Clinical and Assay Data
Viral RNA quantification
- Plasma viral loads Chart
- Pan urine viral loads Chart
- Saliva viral loads Chart
- CSF viral loads Chart
- Amniotic fluid viral loads Chart
- Neutralizing Antibody Titers
-12.13.16 527453: on day 32 of gestation (still prior to infection): We could see two poles (crown and rump), a heartbeat, yolk sac and gestational sac, and placentas. The fetus was viable with no abnormalities in the placenta or sac seen. The measurements obtained were crown rump length, yolk sac, gestational sac, and heart rate.
-12.20.16 527453: on day 39 of gestation (still prior to infection): No abnormalities seen
-12.27.16 527453: on day 46 of gestation (day 0 of infection): No abnormalities seen
-1.3.17 527453: on day 53 of gestation (day 7 post-infection): No abnormalities seen
-1.10.17 527453: on day 60 of gestation (day 14 post-infection): An amniocentesis was attempted but was not successful because we identified that there was still separation of the amnion and chorion. These are usually fused by this point in human pregnancies. Our skilled OB doctor tried in an area that appeared fused but she couldn't get through the membrane safely (without potentially touching the fetus) so the procedure was stopped. Ultrasound also identified persistence of the yolk sac, which we wouldn't expect at this far into pregnancy in humans. Between the chorion and amnion the fluid was heterogenous which could signify a small hemorrhage, which could resolve spontaneously. At the fetal edge of the placenta there is a small hyperechoic area which we will continue to monitor. There did not appear to be any intracranial calcifications or calcifications in the liver or placenta.
-1.17.17 527453: on day 67 of gestation (day 21 post-infection): No abnormalities seen
-1.24.17 527453: on day 74 of gestation (day 28 post-infection): An amniocentesis was successful today. In the ultrasound, the yolk sac had resolved. Between the chorion and amnion over the cervix there was still a large heterogeneous area, measuring almost 3x3x3 which again looks like a hematoma/ prior hemorrhage. With it located over the cervix, there could be some vaginal bleeding (old dark brown blood) but none of that has occurred yet. There was no hyperechoic area today or any bleeding at the prior amniocentesis site. No other abnormalities seen. Amniotic fluid viral load was 1.84e4 vRNA copies/mL and is available in our data sets below.
-1.31.17 527453: on day 81 of gestation (day 35 post-infection): An ultrasound found a possible placental separation from the uterine wall/ retroplacental clot along the edge of the placenta. This may be an abruption and a large blood clot. Since it is over the cervix, we are monitoring for vaginal bleeding (none has been reported yet). The fetus had no abnormalities noted. We are monitoring the pregnancy closely with daily fetal heart rate measurements and monitoring for signs of labor because of these ultrasound findings.
-2.7.17 527453: on day 88 of gestation (day 42 post-infection): An ultrasound found that there was still an area that looked like clotted blood toward the fundus, but that area over the cervix was resolved. The placenta still looks rather calcified. Additionally, the fetal small bowel looks subjectively dilated, and the bowel walls are prominent without being hyperechoic. It's difficult to tell what normal bowel diameter is in a macaque fetus because there are no growth charts for this. We also saw a little debris in the stomach. What probably explains this finding is that the fetus can swallow blood that gets into the amniotic fluid, and this makes the stomach appear to have debris, and can make the bowel a little prominent or even hyperechoic (which wasn't the case here). No signs of fetal distress on daily heart rate measurements. Only an ultrasound, not amniocentesis was performed, because of the ultrasound abnormalities identified last week.
-2.14.17 527453: on day 95 of gestation (day 49 post-infection): An ultrasound found no fetal heartbeat today (despite having a normal heart rate yesterday). Both a maternal and fetal necropsy were performed.
Necropsy and fetectomy tissue viral load Data
- 12.15.16 The first macaque is pregnant and is scheduled for infection on 12/27/16 (animal 527453). Necropsy is scheduled for 3.1.16, which is day 110 of gestation/ day 65 post-infection.
- 1.5.17 Animal 527453 was challenged with Puerto Rican ZIKV on 12/27/16 on gestational day 46 and plasma viremia was detected. This is our first infection using Puerto Rican Zika virus in any of our studies. Viral titers were somewhat lower but within range of other titers when compared with the French Polynesia viral titers in earlier pregnancy studies but peak viremia was delayed. No rash was seen on day 8 post-infection.
- 2.14.17 on day 95 of gestation (day 49 post-infection): An ultrasound found no fetal heartbeat today (despite having a normal heart rate yesterday). Both a maternal and fetal necropsy were performed. A summary of this pregnancy and the necropsy is here.
- 4.29.17 - We sent samples from the fetus to Xiankun (Kevin) Zeng who detected both positive and negative sense ZIKV RNA in multiple tissues. Detection of antisense RNA indicates the presence of actual replicating virus in these tissues, unlike viral loads and positive sense RNA staining. See here for a full description.
- 6.27.17 - Animal 527453 amniotic fluid samples (28 dpi and 49 dpi) were evaluated by plaque assay and were negative. Maternal serum was evaluated for neutralizing antibodies by PRNT and the dam developed a good neutralizing antibody response.
- 146523 was challenged on September 22, 2017 at day 46 of gestation.
- 858972 was challenged on October 6, 2017 at day 47 of gestation.