Researchers at the University of Wisconsin-Madison School of Veterinary Medicine (SVM) have developed one of the first mouse models for the study of Zika virus. The model will allow researchers to better understand how the virus causes disease and aid in the development of antiviral compounds and vaccines.
“The tools have not been available to people who want to be able to test vaccines and antivirals against Zika virus,” says Matthew Aliota, assistant SVM scientist and lead author of the study that describes the model, published April 19 in the journal PLOS Neglected Tropical Diseases. “The caveat is that it’s a mouse model, but it does allow us to test vaccines, and the pathology caused by the virus in the mouse brain could be used to understand the pathology in the brains of humans, especially fetuses.”
Zika virus was first described in Uganda in 1947. Before last year, it had circulated in people in Africa, southeast Asia and in the Pacific Islands and only sporadically caused disease. The virus is transmitted by mosquitoes and typically causes mild, flu-like symptoms, when it causes symptoms at all.
However, in 2015 the virus began infecting unprecedented numbers of people in Brazil and then spread throughout the Americas. Public health officials in the United States expect it to spread to the southern U.S. as the weather warms and activity of the Aedes aegypti mosquito — the species that harbors the virus — subsequently increases.
Last week, the Centers for Disease Control and Prevention (CDC) confirmed Zika virus is responsible for a large rise in brain defects in developing fetuses, including microcephaly. In fact, cases of microcephaly — marked by a small head, reduced brain size and cognitive impairments — were 20 times higher than usual in parts of Brazil last year. There has been some evidence of neurological effects in adults as well.
Researchers now also know the disease can spread through sexual contact.
“It’s scary to know so little about something that can be so devastating,” says Katrina Larkin, a UW-Madison undergraduate student and a study co-author. “Learning how instrumental animal models can be to combating diseases makes this work even more urgent.”
Mouse models allow researchers to conduct larger-scale studies than animal models like nonhuman primates, and to perform experiments that are not possible to conduct in human beings.
The mouse model described by Aliota and the rest of the research team, including Jorge Osorio, professor of pathobiological sciences at SVM, is an immunocompromised mouse the laboratory already possessed for research on viruses similar to Zika, like dengue virus. The team learned they could inject Zika virus into the foot pads of the mice, and under their skin, and the virus would then spread throughout the body, including the brain. Other mouse strains are resistant to infection with Zika virus.