Lack of iNOS facilitates MCMV spread in the retina.
OBJECTIVE
The purposes of this study were to identify iNOS-producing retinal cells and to determine whether lack of iNOS facilitates MCMV spread and replication in the retina.


METHODS
Immunosuppressed (IS) iNOS(-/-) mice or C57BL/6 (wild-type) mice were inoculated with 5 x 10(4) PFU of MCMV K181 strain (K181) via the supraciliary route. Injected eyes were collected at several times after inoculation and examined by plaque assay for replicating virus, RT-PCR for iNOS RNA, Western blot for iNOS protein and by staining for MCMV early antigen (EA), iNOS, and retinal cell antigens.


RESULTS
iNOS mRNA and iNOS proteins were expressed in the MCMV-injected eye of wild-type mice. Most iNOS-producing cells were F4/80-positive, including macrophages, RPE-derived macrophages, and resident microglia. Significantly higher titers of virus were recovered from the injected eyes, and more infected cells were detected in the retina of IS iNOS(-/-) mice than in IS wild-type mice. Retinal necrosis and loss of retinal architecture throughout the retina were noted in IS iNOS(-/-) mice, whereas cytomegalic cells and retinitis were present only in the peripheral retina of IS wild-type mice.


CONCLUSIONS
iNOS produced by macrophages, especially resident macrophages including microglia and RPE derived macrophages, plays an important role in limiting spread of MCMV in the retina.
Zhang
Ming
M
Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, Georgia 30912, USA.
Zhou
Jun
J
Marshall
Brendan
B
Xin
Hua
H
Atherton
Sally S
SS
D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D000956:Antigens, Viral / Q000378:metabolism; D015153:Blotting, Western; D015828:Eye Infections, Viral / Q000201:enzymology / Q000473:pathology / Q000821:virology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006566:Herpesviridae Infections / Q000201:enzymology / Q000473:pathology / Q000821:virology*; D017874:Immediate-Early Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D018146:Muromegalovirus / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012173:Retinitis / Q000201:enzymology / Q000473:pathology / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014779:Virus Replication
D000943:Antigens, Differentiation; D000956:Antigens, Viral; D017874:Immediate-Early Proteins; D012333:RNA, Messenger; C036763:monocyte-macrophage differentiation antigen; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse