Antibodies can fight viruses from within infected cells, reported researchers who now believe that treatments could be applied to viral diseases like the common cold, “winter vomiting,” and gastroenteritis.
Previously, scientists thought that antibodies could only reduce infection by attacking viruses outside cells and by blocking their entry into cells. Once inside the cell, the body’s only defense was to destroy the cell. But protection mediated by antibodies doesn’t end at the cell membrane. It continues inside the cell to provide a last line of defense against infection.
Researchers at the U.K.’s Medical Research Council’s Laboratory of Molecular Biology showed that cells possess a cytosolic IgG receptor, tripartite motif-containing 21 (TRIM21), which binds to antibodies with a higher affinity than any other IgG receptor in the human body. Antibodies remain attached when viruses enter healthy cells.
Once inside, the antibodies trigger a response, led by TRIM21, which pulls the virus into a disposal system used by the cell to get rid of unwanted material. This process happens quickly, and proteasomal targeting leads to rapid degradation of virions in the cytosol before translation of virally encoded genes.
The discovery also opens new avenues to consider while developing the next generation of antiviral drugs. TRIM21 neutralizes viral infection at physiological antibody concentrations, and increasing the amount of TRIM21 protein in cells makes this process even more effective.
The cure for the common cold won’t be ready for this winter, though.
*This blog post was originally published at ACP Internist*