Propagation of human cytomegalovirus (CMV) in cultured cells results in genetic adaptations that confer improved growth in vitro and significant attenuation in vivo. Mutations in RL13 arise quickly, while mutations in the UL128-131A locus emerge later during fibroblast passage and disrupt formation of a glycoprotein complex that is important for entry into epithelial and endothelial cells. As CMV replicates in the context of host antibodies in vivo, we reasoned that antibodies might mitigate the accumulation of adaptive mutations during cell culture passage. To test this, CMV in infant urine was used to infect replicate fibroblast cultures. One lineage was passaged in the absence of CMV-hyperimmuneglobulin (HIG) while the other was passaged with HIG in the culture medium. The former lost epithelial tropism and acquired mutations disrupting RL13 and UL131A expression, whereas the latter retained epithelial tropism and both gene loci remained intact after 22 passages. Additional mutations resulting in single amino acid changes also occurred in UL100 encoding glycoprotein M, UL102 encoding a subunit of the helicase/primase complex, and UL122 encoding the Immediate Early 2 protein. An epitheliotropic RL13+/UL131A+ virus was isolated by limiting dilution in the presence of HIG and expanded to produce a working stock sufficient to conduct cell tropism experiments. Thus, production of virus stocks by culture in the presence of antibodies may facilitate in vitro experiments using viruses that are genetically more authentic than previously available.
Bibliographical noteFunding Information:
Funding: This work was supported by grants R01AI088750 and R21AI073615 (to M.A.M.), 1R01AI128912-01A1 (to M.A.M. and L.H.), R01HD079918 (to M.R.S.), and P01-CA019014 (to D.P.D.) from the National Institutes of Health, and by grant 6-FY17-849 (to M.R.S.) from the March of Dimes Birth Defects Foundation, and by research grants from Merck & Co., Inc. Kenilworth, NJ, the USA (to M.A.M.). The funders had no role in study design, data collection, or interpretation.
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.
- Cell culture
- Cell Line
- Cytomegalovirus/drug effects
- Viral Proteins/genetics
- Virus Replication/drug effects
- Antibodies, Viral/pharmacology
- Viral Tropism/drug effects
- Culture Media/chemistry
- Cell Culture Techniques
- Infant, Newborn
- Virus Internalization/drug effects
PubMed: MeSH publication types
- Research Support, Non-U.S. Gov't
- Journal Article
- Research Support, N.I.H., Extramural