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.

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
<ol>
	<li>Generate recombinant M32-EGFP-MCMV according to the method as follows (1.2 - 1.9) and as previously described8.</li>
	<li>Use recombinant viruses derived from the Smith strain of wild-type MCMV (accession number: U68299). Insert EGFP (4,361 base pai...

<ol>
	<li>Philippe, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pandoraviruses:+amoeba+viruses+with+genomes+up+to+2.5+Mb+reaching+that+of+parasitic+eukaryotes.">Pandoraviruses: amoeba viruses with genomes up to 2.5 Mb reaching that of parasitic eukaryotes.</a> Science. 341 (6143), 281-286 (2013).</li><li>Passini, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraventricular+brain+injection+of+adeno-associated+virus+type+1+(AAV1)+in+neonatal+mice+results+in+complementary+patterns+of+neuronal+transduction+to+AAV2+and+total+long-term+correction+of+storage+lesions+in+the+brains+of+beta-glucuronidase-deficient+mice.">Intraventricular brain injection of adeno-associated virus type 1 (AAV1) in neonatal mice results in complementary patterns of neuronal transduction to AAV2 and total long-term correction of storage lesions in the brains of beta-glucuronidase-deficient mice.</a> J Virol. 77 (12), 7034-7040 (2003).</li><li>Kim, J. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viral+transduction+of+the+neonatal+brain+delivers+controllable+genetic+mosaicism+for+visualising+and+manipulating+neuronal+circuits+in+vivo.">Viral transduction of the neonatal brain delivers controllable genetic mosaicism for visualising and manipulating neuronal circuits in vivo.</a> Eur J Neurosci. 37 (8), 1203-1220 (2013).</li><li>McLean, J. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Widespread+neuron-specific+transgene+expression+in+brain+and+spinal+cord+following+synapsin+promoter-driven+AAV9+neonatal+intracerebroventricular+injection.">Widespread neuron-specific transgene expression in brain and spinal cord following synapsin promoter-driven AAV9 neonatal intracerebroventricular injection.</a> Neurosci Lett. 576, 73-78 (2014).</li><li>Hsu, K. M., Pratt, J. R., Akers, W. J., Achilefu, S. I., Yokoyama, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+cytomegalovirus+displays+selective+infection+of+cells+within+hours+after+systemic+administration.">Murine cytomegalovirus displays selective infection of cells within hours after systemic administration.</a> J Gen Virol. 90. 90 (Pt 1), 33-43 (2009).</li><li>Sakao-Suzuki, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aberrant+fetal+macrophage/microglial+reactions+to+cytomegalovirus+infection.">Aberrant fetal macrophage/microglial reactions to cytomegalovirus infection.</a> Annals of Clinical and Translational Neruology. 1 (8), 570-588 (2014).</li><li>Gombash Lampe, S. E., Kaspar, B. K., Foust, K. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intravenous+injections+in+neonatal+mice.">Intravenous injections in neonatal mice.</a> J Vis Exp. (93), e52037 (2014).</li><li>Kawasaki, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytomegalovirus+initiates+infection+selectively+from+high-level+beta1+integrin-expressing+cells+in+the+brain.">Cytomegalovirus initiates infection selectively from high-level beta1 integrin-expressing cells in the brain.</a> Am J Pathol. 185 (5), 1304-1323 (2015).</li><li>Rahim, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intravenous+administration+of+AAV2/9+to+the+fetal+and+neonatal+mouse+leads+to+differential+targeting+of+CNS+cell+types+and+extensive+transduction+of+the+nervous+system.">Intravenous administration of AAV2/9 to the fetal and neonatal mouse leads to differential targeting of CNS cell types and extensive transduction of the nervous system.</a> FASEB J. 25 (10), 3505-3518 (2011).</li><li>Cannon, M. J., Davis, K. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Washing+our+hands+of+the+congenital+cytomegalovirus+disease+epidemic.">Washing our hands of the congenital cytomegalovirus disease epidemic.</a> Bmc Public Health. 5, (2005).</li><li>Frenkel, L. D., Keys, M. P., Hefferen, S. J., Rola-Pleszczynski, M., Bellanti, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unusual+eye+abnormalities+associated+with+congenital+cytomegalovirus+infection.">Unusual eye abnormalities associated with congenital cytomegalovirus infection.</a> Pediatrics. 66 (5), 763-766 (1980).</li><li>Becroft, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prenatal+cytomegalovirus+infection:+epidemiology,+pathology+and+pathogenesis.">Prenatal cytomegalovirus infection: epidemiology, pathology and pathogenesis.</a> Perspect Pediatr Pathol. 6, 203-241 (1981).</li><li>Conboy, T. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intellectual+development+in+school-aged+children+with+asymptomatic+congenital+cytomegalovirus+infection.">Intellectual development in school-aged children with asymptomatic congenital cytomegalovirus infection.</a> Pediatrics. 77 (6), 801-806 (1986).</li><li>Fowler, K. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+outcome+of+congenital+cytomegalovirus+infection+in+relation+to+maternal+antibody+status.">The outcome of congenital cytomegalovirus infection in relation to maternal antibody status.</a> N Engl J Med. 326 (10), 663-667 (1992).</li><li>Cannon, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Congenital+cytomegalovirus+(CMV)+epidemiology+and+awareness.">Congenital cytomegalovirus (CMV) epidemiology and awareness.</a> J Clin Virol. 46 Suppl 4, S6-S10 (2009).</li><li>Grassi, M. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglial+nodular+encephalitis+and+ventriculoencephalitis+due+to+cytomegalovirus+infection+in+patients+with+AIDS:+two+distinct+clinical+patterns.">Microglial nodular encephalitis and ventriculoencephalitis due to cytomegalovirus infection in patients with AIDS: two distinct clinical patterns.</a> Clin Infect Dis. 27 (3), 504-508 (1998).</li><li>Kawasaki, H., Mocarski, E. S., Kosugi, I., Tsutsui, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclosporine+inhibits+mouse+cytomegalovirus+infection+via+a+cyclophilin-dependent+pathway+specifically+in+neural+stem/progenitor+cells.">Cyclosporine inhibits mouse cytomegalovirus infection via a cyclophilin-dependent pathway specifically in neural stem/progenitor cells.</a> J Virol. 81 (17), 9013-9023 (2007).</li><li>Britt, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+cytomegalovirus:+propagation,+quantification,+and+storage.">Human cytomegalovirus: propagation, quantification, and storage.</a> Curr Protoc Microbiol. Chapter 14, Unit 14E 13 (2010).</li><li>Kawasaki, H., Kosugi, I., Arai, Y., Iwashita, T., Tsutsui, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+embryonic+stem+cells+inhibit+murine+cytomegalovirus+infection+through+a+multi-step+process.">Mouse embryonic stem cells inhibit murine cytomegalovirus infection through a multi-step process.</a> PLoS One. 6 (3), e17492 (2011).</li><li>Gage, G. J., Kipke, D. R., Shain, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole+animal+perfusion+fixation+for+rodents.">Whole animal perfusion fixation for rodents.</a> J Vis Exp. (65), (2012).</li><li>Fischer, A. H., Jacobson, K. A., Rose, J., Zeller, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cutting+sections+of+paraffin-embedded+tissues.">Cutting sections of paraffin-embedded tissues.</a> CSH Protoc. , (2008).</li><li>Chi, V., Chandy, K. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunohistochemistry:+paraffin+sections+using+the+Vectastain+ABC+kit+from+vector+labs.">Immunohistochemistry: paraffin sections using the Vectastain ABC kit from vector labs.</a> J Vis Exp. (8), e308 (2007).</li><li>Wilsbacher, L. D., Coughlin, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+cardiomyocyte+development+using+immunofluorescence+in+embryonic+mouse+heart.">Analysis of cardiomyocyte development using immunofluorescence in embryonic mouse heart.</a> J Vis Exp. (97), (2015).</li><li>Ohshima, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraperitoneal+and+intravenous+deliveries+are+not+comparable+in+terms+of+drug+efficacy+and+cell+distribution+in+neonatal+mice+with+hypoxia-ischemia.">Intraperitoneal and intravenous deliveries are not comparable in terms of drug efficacy and cell distribution in neonatal mice with hypoxia-ischemia.</a> Brain Dev. 37 (4), 376-386 (2015).</li><li>Kim, J. Y., Grunke, S. D., Levites, Y., Golde, T. E., Jankowsky, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracerebroventricular+viral+injection+of+the+neonatal+mouse+brain+for+persistent+and+widespread+neuronal+transduction.">Intracerebroventricular viral injection of the neonatal mouse brain for persistent and widespread neuronal transduction.</a> J Vis Exp. (91), e51863 (2014).</li><li>Glascock, J. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delivery+of+therapeutic+agents+through+intracerebroventricular+(ICV)+and+intravenous+(IV)+injection+in+mice.">Delivery of therapeutic agents through intracerebroventricular (ICV) and intravenous (IV) injection in mice.</a> J Vis Exp. (56), (2011).</li></ol>

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. ...

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. ICV inoculation with virus is often used to establish central nervous system (CNS) infections in mice. Studies using this technique report widespread infection, particularly of cells in the periventricular zones and in regions of the brain in direct contact with the cerebrospinal fluid (CSF), similar to the effects of viral ventriculoencephalitis. The small size of adeno-associated virus (AAV) particles (20 - 25 nm in diameter) facilitates their dissemination throughout the brain in ICV infections2-4. Intraperitoneal5, direct placental6, and IV injections7 represent hematogenic systemic administration. The penetration of viral particles through the blood-brain barrier (BBB) allows them to reach the parenchyma of the neonatal brain, representing diffuse microglial nodules8,9.
Cytomegalovirus (CMV) is a common virus that belongs to the herpes virus family. In the United States, 50% - 80% of the people have had CMV infection by age 40. CMV infections are rarely harmful but can cause diseases in immunocompromised patients and fetuses. Of all deliveries, 0.2% - 2% are born with CMV10, resulting in severe symptoms such as microcephaly, periventricular calcification, cerebellar hypoplasia, microphthalmia, and optic nerve atrophy11,12. Furthermore, mental retardation, sensorineural hearing loss, visual defects, seizure, and epilepsy occur in about 10% of non-fatally CMV-infected infants13,14. CNS dysfunction is the most common characteristic symptom of CMV congenital anomaly. More children are permanently disabled each year by congenital CMV than by Down syndrome, fetal alcohol syndrome, or spina bifida15. There are no vaccinations against CMV available at the present, calling for a need of a safe and effective vaccine. Studying the interaction of CMV particles with their receptors in the earliest phase of infection is important to understand the effect of vaccination.
Ventriculoencephalitis and diffuse microglial nodules are the two main pathological characteristics of CMV encephalitis16. It has been uncertain how the CMV particles (150 - 300 nm) spread through the brain in the acute phase of infection and how the distribution of cellular receptors and their affinity for viruses contribute to the viral spread. Kawasaki et al. have evaluated ICV and IV infections from the perspective of the distribution of particles and their receptors (&#946;1 integrin) in the earliest phase of infection. We have found that the dissemination of CMV particles and the expression of &#946;1 integrin are well correlated in the earliest phase of infection in both ICV and IV infections8. ICV infection is a model of ventriculoencephalitis and IV infection is a model of diffuse microglial nodules. Studying the dynamics of viral or fluorescent particles would give useful information on the effect of particle size, viral interactions with cellular receptors, and the mechanism of BBB penetration in the brain. The following protocol could be used to investigate any viral infection and viral vector in the CNS.

<table border="0" cellpadding="0" cellspacing="0" width="690">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:323px;">Tris; tris(hydroxymethyl)- aminomethane</td>
			<td style="width:143px;">Sigma-Aldrich</td>
			<td style="width:80px;">T-6791</td>
			<td style="width:147px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HCl</td>
			<td>Sigma-Aldrich</td>
			<td>H-1758</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">pEGFP-N1 vector&#160;</td>
			<td>Clontech</td>
			<td>#6085-1</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:23px;">D-sorbitol</td>
			<td>Sigma-Aldrich</td>
			<td>S-1876</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SPHERO TM Fluorescent Polystyrene Nile Red 0.04-0.06</td>
			<td>Spherotech, Inc.</td>
			<td>FP-00556-2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SPHERO TM Fluorescent Polystyrene Nile Red 0.1-0.3</td>
			<td>Spherotech, Inc.</td>
			<td>FP-0256-2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SPHERO TM Fluorescent Polystyrene Nile Red 1.7-2.2</td>
			<td>Spherotech, inc.&#160;</td>
			<td>FP-2056-2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10% mouse serum</td>
			<td>DAKO&#160;</td>
			<td>X0910</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">C57BL/6 mouse</td>
			<td>SLC, Inc.</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ICR mouse</td>
			<td>SLC, Inc.</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:323px;">Modified Microliter Syringes (7000 Series)</td>
			<td>Hamilton company</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">35-gauge needle</td>
			<td>Saito Medical</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">A Wee Sight Transilluminator</td>
			<td>Phillips Healthcare</td>
			<td>1017920</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">O.C.T.Compound</td>
			<td>Sakura Finetek</td>
			<td>4583</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RNase A</td>
			<td>Sigma-Aldrich</td>
			<td>R4642</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nonidet(R) P-40</td>
			<td>Nacalai</td>
			<td>25223-04</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">citrate buffer (pH6) x10</td>
			<td>Sigma-Aldrich</td>
			<td colspan="2">C9999-100ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">pepsin</td>
			<td>Sigma-Aldrich</td>
			<td>P6887</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EDTA</td>
			<td>dojindo</td>
			<td>N001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Formamide</td>
			<td>TCI</td>
			<td>F0045</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dextran sulfate sodium salt</td>
			<td>Sigma-Aldrich</td>
			<td>42867-5G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Denhardt&#39;s Solution (50X)</td>
			<td>ThermoFishcer sceintific</td>
			<td>750018</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Yeast tRNA (10 mg/mL)</td>
			<td>ThermoFishcer sceintific</td>
			<td>AM7119</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SSC x20</td>
			<td>Sigma-Aldrich</td>
			<td>S6639</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DAPI</td>
			<td>ThermoFishcer sceintific</td>
			<td>D1306</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">n-Hexane</td>
			<td>Sigma-Aldrich</td>
			<td>296090</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">superfrost plus glass</td>
			<td>ThermoFishcer sceintific</td>
			<td>12-55-18</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cytokeep II</td>
			<td>Nippon Shoji Co.</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FITC-conjugated Griffonia simplicifolia isolectin B4</td>
			<td>Vector laboratories, Inc.</td>
			<td>L1104</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Mouse CD31 (PECAM-1) PE</td>
			<td>ebioscience</td>
			<td>12-0311</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ProLong&#160; Gold</td>
			<td>ThermoFishcer sceintific</td>
			<td>P36934</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BIOREVO</td>
			<td>KEYENCE</td>
			<td style="width:80px;">BZ-9000E</td>
			<td></td>
		</tr>
	</tbody>
</table>

intracerebroventricular and intravascular injection of viral particles and fluorescent microbeads into the neonatal brain

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 &#181;l of murine CMV (MCMV) or fluorescent microbeads were injected into the lateral ventricle at the midpoint between the ear and eye using a 10-&#181;l 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 &#181;l 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.

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...

Watch this Scientific Journal Video about Intracerebroventricular and Intravascular Injection of Viral Particles and Fluorescent Microbeads into the Neonatal Brain at JoVE.com

Intracerebroventricular and Intravascular Injection of Viral Particles and Fluorescent Microbeads into the Neonatal Brain

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 ...

The overall goal of this procedure is to observe the distribution of viral particles during the acute phase of infection in the central nervous system. This method can help answer key questions in the neurovirology field. Such as how do virus particles distribute in the immature central nervous system during the acute infection phase.The main advantage of this technique is that the initial distribution of viral particles can be observed directly with a microscope using two simple methods. Such as intercerebroventricular and intravascular injection. Begin my sterilizing a 10 microliter syringe and a 27 gauge needle with 70%alcohol.Then load five microliters of murine cytomegalovirus injection solution or fluorescent microbeads into the needle by carefully pulling the plunger of the syringe. After anesthetizing and immobilizing a PO.5 neonatal mouse by placing it on ice for three to four minutes, use the toe pinch response method to determine the depth of anesthesia. Mark the injection site on the anesthetized mouse with a non toxic laboratory pen at a location approximately 0.7 to 1.0 mm lateral to the saggital suture and 0.7 to 1.0 mm cuddle from the neonatal bregma.This diagram shows the site in more detail. For reference, mark 2 mm from the tip of the needle with a non toxic marker. Next, insert the needle 2 mm deep perpendicular to the skull surface at the marked injection site.Then slowly inject 5 microliters of murine cytomegalovirus into the lateral ventricle without opening the scalp. In another group of mice inject a 5 microliter solution containing fluorescent microbeads by the same method. After injection, allow the needle to remain in place for 10 to 20 seconds to prevent backflow.Then slowly remove the needle. Allow the injected animals to recover for 5 to 10 minutes in a warm container until movement and general responsiveness are restored. For intravenous injection secure the anesthetized neonate to the transilluminator using surgical tape and then visualize the superficial temporal vein.Next, while wearing 1.5x magnifying glasses use a 1 ml syringe with a 35 gauge needle to slowly infuse 50 microliters of murine cytomegalovirus virus into the superficial temporal vein. Again repeat the procedure with fluorescent microbeads of the appropriate size in the control group. After removing the needle use gauze containing 70%alcohol to apply pressure to the injection site until the bleeding ceases.Give the neonate approximately five minutes in a warm container to recover before returning it to the cage. Two hours after introcerbroventricular injection in the acute infection phase green recombinant M32 EGFP MCMV particles are mainly observed in the marginal area as indicated by the arrows and seen in the magnified region. At this time the M32 EGFP MCMV particles are also seen in the choroid plexus and subventricular zone.The MCMV genome is first detected in the subventricular zone at three hours post intracerebralventricular injection. Using fluorescent and C2 hybridization the MCV genome is visible as green spots and indicated by arrows in this magnified region. At three hours post intravenous injection the MCMV particles visible as green spots and indicated by arrows are found inside and outside of the vascular area of the parenchyma, as this increased magnification image demonstrates.At this time the MCMV particles are still visible in the choroid plexus and subventricular zone. Using fluorescent and C2 hybridization the MCMV genome is detected in the vascular area and meninges at 12 hours post IV injection. As indicated by the arrows.Once mastered, this technique can be done in five minutes if it is performed properly. After watching this video you should have a good understanding of how to observe the distribution of viral particles during the acute phase of infection in the central nervous system. Don't forget that working with a virus can be extremely hazardous and precaution such as wearing masks and gloves should always be taken while performing this procedure.

intracerebroventricular-intravascular-injection-viral-particles

Research

JoVE Journal

Neuroscience

19.0K vistas.  Hamamatsu University School of Medicine. The overall goal of this procedure is to observe the distribution of viral particles during the acute phase of infection in the central nervous system. This method can help answer key questions in the neurovirology field. Such as how do virus particles distribute in the immature central nervous system during the acute infection phase.The main advantage of this technique is that the initial distribution of viral particles can be observed directly with a microscope using two simple metho...