Adverse outcomes in SARS-CoV-2–infected pregnant mice are gestational age–dependent and resolve with antiviral treatment
Patrick S. Creisher, Jamie L. Perry, Weizhi Zhong, Jun Lei, Kathleen R. Mulka, W. Hurley Ryan III, Ruifeng Zhou, Elgin H. Akin, Anguo Liu, Wayne Mitzner, Irina Burd, Andrew Pekosz, Sabra L. Klein
Patrick S. Creisher, Jamie L. Perry, Weizhi Zhong, Jun Lei, Kathleen R. Mulka, W. Hurley Ryan III, Ruifeng Zhou, Elgin H. Akin, Anguo Liu, Wayne Mitzner, Irina Burd, Andrew Pekosz, Sabra L. Klein
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Research Article Reproductive biology

Adverse outcomes in SARS-CoV-2–infected pregnant mice are gestational age–dependent and resolve with antiviral treatment

Abstract

SARS-CoV-2 infection during pregnancy is associated with severe COVID-19 and adverse fetal outcomes, but the underlying mechanisms remain poorly understood. Moreover, clinical studies assessing therapeutics against SARS-CoV-2 in pregnancy are limited. To address these gaps, we developed a mouse model of SARS-CoV-2 infection during pregnancy. Outbred CD1 mice were infected at E6, E10, or E16 with a mouse-adapted SARS-CoV-2 (maSCV2) virus. Outcomes were gestational age–dependent, with greater morbidity, reduced antiviral immunity, greater viral titers, and impaired fetal growth and neurodevelopment occurring with infection at E16 (third trimester equivalent) than with infection at either E6 (first trimester equivalent) or E10 (second trimester equivalent). To assess the efficacy of ritonavir-boosted nirmatrelvir, which is recommended for individuals who are pregnant with COVID-19, we treated E16-infected dams with mouse-equivalent doses of nirmatrelvir and ritonavir. Treatment reduced pulmonary viral titers, decreased maternal morbidity, and prevented offspring growth restriction and neurodevelopmental impairments. Our results highlight that severe COVID-19 during pregnancy and fetal growth restriction is associated with heightened virus replication in maternal lungs. Ritonavir-boosted nirmatrelvir mitigated maternal morbidity along with fetal growth and neurodevelopment restriction after SARS-CoV-2 infection. These findings prompt the need for further consideration of pregnancy in preclinical and clinical studies of therapeutics against viral infections.

Authors

Patrick S. Creisher, Jamie L. Perry, Weizhi Zhong, Jun Lei, Kathleen R. Mulka, W. Hurley Ryan III, Ruifeng Zhou, Elgin H. Akin, Anguo Liu, Wayne Mitzner, Irina Burd, Andrew Pekosz, Sabra L. Klein

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Figure 3

Third trimester–equivalent maSCV2 infection disrupts the trophoblast layer of the placental labyrinth zone and cytokine concentrations.

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Third trimester–equivalent maSCV2 infection disrupts the trophoblast lay...
At E16, pregnant dams were intranasally inoculated with 1 × 105 TCID50 of maSCV2 or mock inoculated with media and euthanized at 3 DPI to collect placentas. Representative H&E images (A) were taken at ×5 (upper panels) and ×20 magnification (lower panels, and specific areas of interest further zoomed 1.75-fold (black box). Within H&E-stained placentas, arrows indicate trophoblast giant cells and the letter M in each lower panel indicates maternal blood spaces. Mononucleated trophoblast giant cells were identified and counted at ×20 magnification. Scale bars: 1mm (upper panels) and 40 μM (A, lower panels), (B). Placentas were immunostained for cytokeratin (C, red) to mark trophoblasts or vimentin (D, red) to mark endothelial cells and DAPI (blue) to label nuclei, with controls without primary antibody run in parallel. Representative images were taken at ×20 magnification. Quantification of the percentage positive area for each marker is shown (E and F). Placentas were homogenized and analyzed by ELISA for IFN-β (G) IL-1β (H). Bars represent the mean ± SEM (n = 5–10/group) with each shape indicating one placenta. For analysis of images, each shape is the mean quantification or count of 6 fields of view. Statistical significance was determined by unpaired 2 tailed t test. Scale bar: 100 μm (C and D). *P < 0.05.