Getting dengue first may make Zika infection much worse

dengue antibody and dengue virus
FRIEND OR FOE A dengue antibody (blue, shown bound to a dengue virus protein, red, in this molecular model) can ease Zika’s entry into cells, a new study finds.

Being immune to a virus is a good thing, until it’s not. That’s the lesson from a study that sought to understand the severity of the Zika outbreak in Brazil. Experiments in cells and mice suggest that a previous exposure to dengue or West Nile can make a Zika virus infection worse.

“Antibodies you generate from the first infection … can facilitate entry of the Zika virus into susceptible cells, exacerbating the disease outcome,” says virologist Jean K. Lim. Lim and colleagues report the results online March 30 in Science.

The study is the first to demonstrate this effect in mice, as well as the first to implicate West Nile virus, notes Sharon Isern, a molecular virologist at Florida Gulf Coast University in Fort Myers.

Zika is similar to other members of its viral family, the flaviviruses. It shares about 60 percent of its genetic information with dengue virus and West Nile virus. Dengue outbreaks are common in South and Central America, and dengue as well as West Nile are endemic to the United States.

Exposure to a virus spurs the body to create antibodies, which prevent illness when a subsequent infection with the virus occurs. But a peculiar phenomenon called antibody-dependent enhancement has been described in dengue patients (SN: 6/25/16, p. 22). The dengue virus has four different versions. When a person with immunity to one dengue type becomes sick with another type, the illness is worse the second time. The antibodies from the previous dengue exposure actually help the subsequent dengue virus infect cells, rather than blocking them.

Outcomes of Zika infections for mice depended on whether certain viral antibodies were present in their systems….

Rapid Ebola test to detect early infection in the works

Ebola virus
TEAM PLAYERS Researchers are designing antibody pairs that can help detect the Ebola virus (shown) sooner.

WASHINGTON — Diagnosing Ebola earlier is becoming almost as easy as taking a home pregnancy test.

Scientists are developing antibodies for a test that can sniff out the deadly virus more quickly and efficiently than current tests, researchers reported February 6 at the American Society for Microbiology Biothreats meeting.

Detecting Ebola’s genetic material in patients’ blood samples now takes a full day and requires access to a specialized laboratory. Simpler and speedier tests are available. They use antibodies — specialized proteins that latch onto and flag virus particles — and work somewhat like a pregnancy test. Within…