Human cytomegalovirus (HCMV) infects many people; it's been estimated that by the time people are adults, about half of us have been infected. But this virus doesn't usually cause symptoms so it may go unnoticed. However, it can be dangerous to people who are immunocompromised, or to the growing fetus.
Researchers have now used an advanced genetic technique to learn more about what happens to cells when they are infected by HCMV. The CRISPR gene editing tool was combined with single cell sequencing to create PerturbSeq, which was applied in this study. The findings have been reported in Nature Biotechnology.
“Basically, you perturb genes in a cell population and then you read out what happens to the cells, not just by measuring survival, but by actually looking at the pattern of gene expression in those cells over time,” said first study author Marco Hein, a former postdoctoral researcher in the lab of Howard Hughes Medical Institute Investigator Jonathan Weissman of the Whitehead Institute.
In this work, CRISPR was used to eliminate the expression of genes systematically, and the impact of that elimination was examined. This study analyzed gene expression at the single-cell level in a large population of cells, revealing how viral and human genes interact. The scientists identified viral and host cell genes that were important to the virus, some were necessary for replication while others are involved in immunity, for example.
“Now that we have this list, we have a list of potential targets that one might now go ahead and develop drugs against,” said Hein.
HCMV has a genome made of double-stranded DNA, like the mammalian genome. CRISPR tools that are aimed at the viral genome might also work on a host cell genome. Targeting the genome of the host cell would carry more risk, however, and would necessitate more research before it was applied.
This approach may be useful in the study of other viruses. Though some have genomes made of RNA that is not typically targeted with CRISPR, it may still show how a host cell's genome is involved in the progression of an infection.
Sources: Whitehead Institute, Nature Biotechnology