After infection of monkeys, Zika virus is rapidly cleared from the blood but persists in semen and saliva for at least one month, reports a paper published online in Nature Medicine this week. Moreover, infection with Zika virus prompts an immune response and protection against later challenge with another strain of the virus.
Zika virus infection results in flu-like symptoms in most human adults who are infected, but in pregnant women it can cause severe neurological damage to the developing fetus. Although most attention has been focused on Zika transmission by mosquitoes, case reports suggest that other routes of transmission are possible.
Seeking to understand how Zika virus moves through the body and how the body responds to Zika virus, James Whitney and colleagues tracked the dynamics of two different Zika virus strains in two species of macaques. By measuring virus abundance in various body fluids and solid tissues at a range of time points in 36 nonhuman primates, the authors found that Zika virus moves through different tissues at different speeds, and that it remains detectable for much longer in some tissues than in others. The authors also tracked the immune response to Zika virus and identified several types of immune cell as targets of the virus.
Although it is not clear whether these characteristics of the virus apply to humans, the findings suggest that further analysis of Zika virus abundance in human semen and saliva is warranted to identify potential routes of sexual and/or household transmission. This work also indicates that multiple monkey species might be suitable models in which to screen candidate Zika virus therapies.