Published: July 24th, 2016
Here, we describe a simple method of intracerebroventricular and intravascular injection of viral particles or fluorescent microbeads into the neonatal mouse brain. The localization pattern of the virus and nanoparticles could be detected by microscopic evaluation or by in situ hybridization.
In the study on the pathogenesis of viral encephalitis, the infection method is critical. The first of the two main infectious routes to the brain is the hematogenous route, which involves infection of the endothelial cells and pericytes of the brain. The second is the intracerebroventricular (ICV) route. Once within the central nervous system (CNS), viruses may spread to the subarachnoid space, meninges, and choroid plexus via the cerebrospinal fluid. In experimental models, the earliest stages of CNS viral distribution are not well characterized, and it is unclear whether only certain cells are initially infected. Here, we have analyzed the distribution of cytomegalovirus (CMV) particles during the acute phase of infection, termed primary viremia, following ICV or intravascular (IV) injection into the neonatal mouse brain. In the ICV injection model, 5 µl of murine CMV (MCMV) or fluorescent microbeads were injected into the lateral ventricle at the midpoint between the ear and eye using a 10-µl syringe with a 27 G needle. In the IV injection model, a 1-ml syringe with a 35 G needle was used. A transilluminator was used to visualize the superficial temporal (facial) vein of the neonatal mouse. We infused 50 µl of MCMV or fluorescent microbeads into the superficial temporal vein. Brains were harvested at different time points post-injection. MCMV genomes were detected using the in situ hybridization method. Fluorescent microbeads or green fluorescent protein expressing recombinant MCMV particles were observed by fluorescent microscopy. These techniques can be applied to many other pathogens to investigate the pathogenesis of encephalitis.
When studying viral encephalitis, the initial distribution of viral particles is very important to understand disease pathogenesis and to identify viral targets in the brain. Most viruses range in size from 20 to 300 nm, although the Pandoravirus is more than 700 nm in size1. The distribution of the viral particles in the acute phase of infection may depend on the size of the particles, the distribution of cellular receptors, or the affinity of the cellular receptors for viruses. In animal models, intracerebroventricular (ICV), intraperitoneal, direct placental, and intravenous (IV) infections have been used to study the pathogenesis of viral encephalitis. ....
All the experimental protocols were approved by the Animal Care Committee of Hamamatsu University of School of Medicine.
1. Preparation of MCMV (Smith strain) and Recombinant M32-enhanced Green Fluorescent Protein (EGFP)-MCMV
In studies on the pathogenesis of viral encephalitis, the infection method is important. The hematogenous route represents an acute infection of the endothelial cells and pericytes of the brain, while the ICV route represents an acute infection spreading via the CSF through the subarachnoid space, reaching to the meninges and choroid plexus. To analyze the first distribution of particles in acute encephalitis, in situ hybridization detecting the MCMV genomes and direct observatio.......
In animal models, ICV, intraperitoneal, direct placental, and IV infections have been used to study the pathogenesis of viral encephalitis. We focused on the ICV and IV injection models of neonatal mice for the simplicity of the procedures and the benefit of direct injection of particles into the target region. Although intraperitoneal infection is an easy method, viral particles spread systemically via an indirect process5,24. Direct placental infection is a good method to study embryonic systemic infection. .......
The authors thank Mr. Masaaki Kaneta, Ms. Hiromi Suzuki, and Ms. Mitsue Kawashima (Department of Regenerative and Infectious Pathology, Hamamatsu University School of Medicine) for their excellent technical assistance. This work was supported by the Japan Society for the Promotion of Science, KAKENHI Grant Number 23590445.....
|Tris; tris(hydroxymethyl)- aminomethane
|SPHERO TM Fluorescent Polystyrene Nile Red 0.04-0.06
|SPHERO TM Fluorescent Polystyrene Nile Red 0.1-0.3
|SPHERO TM Fluorescent Polystyrene Nile Red 1.7-2.2
|10% mouse serum
|Modified Microliter Syringes (7000 Series)
|A Wee Sight Transilluminator
|citrate buffer (pH6) x10
|Dextran sulfate sodium salt
|Denhardt's Solution (50X)
|Yeast tRNA (10 mg/mL)
|superfrost plus glass
|Nippon Shoji Co.
|FITC-conjugated Griffonia simplicifolia isolectin B4
|Vector laboratories, Inc.
|Anti-Mouse CD31 (PECAM-1) PE
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