Establishing Mouse Models for Zika Virus-induced Neurological Disorders Using Intracerebral Injection Strategies: Embryonic, Neonatal, and Adult

Protocol for in utero injection to investigate Zika virus-related fetal microcephaly in mice

Zika virus (ZIKV) is linked to congenital defects including microcephaly. An infection model that can recapitulate most microcephaly-related phenotypes is crucial for understanding ZIKV pathogenesis. Here, we present a protocol to generate ZIKV from an infectious clone through a reverse genetic system and subsequently perform embryonic brain infection with the rescued ZIKV in pregnant mice. We optimized several aspects of the procedures including virus rescue and in utero injection. This protocol facilitates reproducible investigation of virus-induced cortical development defects.

For complete details on the use and execution of this protocol, please refer to Zeng et al. (2020)

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Workflow of Zika virus (ZIKV) preparation from an infectious clone

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Protocol for in utero ZIKV injection

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Details for brain sampling after ZIKV injection

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Guidelines for ZIKV-related microcephaly phenotype analysis

Reversing neural circuit and behavior deficit in mice exposed to maternal inflammation by Zika virus

Zika virus (ZIKV) infection during pregnancy is linked to various developmental brain disorders. Infants who are asymptomatic at birth might have postnatal neurocognitive complications. However, animal models recapitulating these neurocognitive phenotypes are lacking, and the circuit mechanism underlying behavioral abnormalities is unknown. Here, we show that ZIKV infection during mouse pregnancy induces maternal immune activation (MIA) and leads to autistic-like behaviors including repetitive self-grooming and impaired social memory in offspring. In the medial prefrontal cortex (mPFC), ZIKV-affected offspring mice exhibit excitation and inhibition imbalance and increased cortical activity. This could be explained by dysregulation of inhibitory neurons and synapses, and elevated neural activity input from mPFC-projecting ventral hippocampus (vHIP) neurons. We find structure alterations in the synaptic connections and pattern of vHIP innervation of mPFC neurons, leading to hyperconnectivity of the vHIP-mPFC pathway. Decreasing the activity of mPFC-projecting vHIP neurons with a chemogenetic strategy rescues social memory deficits in ZIKV offspring mice. Our studies reveal a hyperconnectivity of vHIP to mPFC projection driving social memory deficits in mice exposed to maternal inflammation by ZIKV.

Thermoacoustic tomography of germinal matrix hemorrhage in neonatal mouse cerebrum

BACKGROUND

Microwave-induced thermoacoustic tomography (TAT) has potential for detecting germinal matrix hemorrhage (GMH). However, it has not been demonstrated in vivo.

OBJECTIVE

To demonstrate the feasibility of TAT for in vivo detecting GMH by using neonatal mouse.

METHODS

A cylindrical-scanning TAT system was developed with optimized microwave irradiation and ultrasound detection for neonatal mouse imaging. Neonatal mice were used to develop GMH model by injection of autologous blood into the periventricular region. After TAT experiments, the animals were sacrificed, frozen and excised to validate the TAT findings. The detailed comparative analyses of the TAT images and corresponding photographs of the excised brain tissues were conducted.

RESULTS

Satisfactory matches are identified between the TAT images and corresponding histological sections, in terms of the shape and size of the brain tissues. Some organs and tissues were also identified. Particularly, comparing to the corresponding histological sections, using TAT enables to more accurately detect the hematoma region at different depths in the neonatal mouse brain.

CONCLUSIONS

This study demonstrates for the first time that TAT can detect GMH in neonatal mouse cerebrum in vivo. This represents the first important step towards the in vivo diagnosis and grading of hemorrhage in the infant human brain.