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Despite the availability of a potent vaccine, outbreaks of measles continue to occur around the world. Two major factors contribute to this prevalence. First, the measles virus is highly transmissible and may be spread through the air in droplets produced by breathing, sneezing and coughing. Within 2 weeks of exposure to the virus, about 90% of unvaccinated individuals will develop infection. Second, vaccine coverage is incomplete because some people lack access while others decline vaccination. Once a person is infected with the virus, there is no effective treatment. For these reasons, the measles virus poses a concerning risk to public health. But epidemiologists working to eradicate the measles may now have a new tool at their fingertips. Researchers at Georgia State University and Emory University (both in Atlanta, GA), along with international collaborators, developed an antiviral drug that effectively protected ferrets from infection with canine distemper virus (CDV), a morbillivirus closely related to measles. The measles virus could not be tested in the ferret model because only primates are susceptible to it.

Ferrets were treated with the antiviral drug for 2 weeks beginning 3 days after exposure to CDV. The disease was completely suppressed, with all of the treated animals surviving the infection and developing immunity against future infection with CDV (Sci. Transl. Med. 6, 232ra52; 2014). The research team, led by Richard Plemper, next plans to test the drug's efficacy against the measles virus using squirrel monkeys.

The antiviral drug, called ERDRP-0519, is intended not as a replacement for the measles vaccine but as a preemptive treatment for avoiding infection in unvaccinated individuals who may have been exposed to the virus. “We strongly support vaccination,” Plemper told Scientific American, continuing, “This drug was not developed as an alternative to vaccination but rather as an additional weapon in our arsenal against the virus that may enable us to improve disease management and rapidly silence outbreaks.” The researchers hope that ERDRP-0519 can be used in synergy with the measles vaccine to fill gaps in vaccine coverage. “Combined, they may one day succeed in eradicating measles totally,” said Plemper in New Scientist.

One potential obstacle to achieving this goal is the possibility that strains of the virus may become resistant to ERDRP-0519. Drug-resistant strains of measles virus in the lab were less transmissible or less virulent than the parent strain, however, leading the researchers to conclude that the clinical significance of such strains would be minimal.