21. Just One Amino Acid
Nikolaus Osterrieder
Nikolaus Osterrieder, Microbiology and Immunology, and a collaborator discovered that a tiny chemical change in horse herpes virus (a relative of the chickenpox virus in humans) could make the difference between triggering a cold or a life-threatening neurological disorder. The researchers showed that varying a single amino acid in an enzyme that is part of the DNA copying process of equid herpesvirus type 1 (EHV-1) creates a more serious type of EHV-1, which causes neurological disorders in horses. Both types of EHV-1 can cause abortions. The research proved that there are two distinct pathotypes of EHV-1, and one of them is likely to cause the neurological disease. After cloning the genome of the virus obtained from a mare that had developed neurological symptoms and lost a fetus, the researchers altered one amino acid in the viral enzyme, DNA polymerase, and rendered the virus unable to cause neurological disease. The amino acid change reduced levels of the virus in the horse’s bloodstream, and lower levels of the virus reached the central nervous system. The mutation also made the virus more susceptible to antiviral drugs. The researchers believe the reduced replication and levels of virus in the blood may be why one form of the virus does not cause neurological disorders. The horse herpes virus lives in horses’ nostrils and is commonly spread by droplets in the air. Horses remain infected for life. Because EHV-1 is a virus, prevention is crucial.