Dengue antibodies may make Zika more deadly
The Zika virus' proximity to Dengue can mean that pre-existing immunity to Zika may enhance Dengue virus disease severity, say scientists at Florida Gulf Coast University, adding that antibodies from a prior Dengue virus infection can also greatly enhance Zika virus production. Immunity to Zika is possible if a child becomes infected before they reach puberty, however, like Zika, there is no official vaccine to treat Dengue. On another note, it was reported that due to the high costs and low rewards of the Zika-elimination business, as well as it being a niche market, there is fast becoming a global shortage of effective insecticides.

There are four different types of the Dengue virus, called serotypes, writes Isern. Antibodies produced during infection with one Dengue serotype will lead to lifelong immunity against only that kind of the virus, so if someone is infected with a different serotype later in life, they will not have immunity against it.

In the second infection, the antibodies from the first infection will bind to the new virus type, but can’t prevent it from infecting cells. In this instance, the bound antibodies can transport the viruses to immune cells that are not normally infected by Dengue. This can lead the virus to reproduce rapidly in these cells and lead to severe Dengue. This process, says Isern, is called antibody-dependent enhancement (ADE).

As Zika is closely related to Dengue, research has shown that preexisting immunity to Zika can enhance Dengue virus disease severity. Isern and her team studied the Zika virus to find that antibodies from a prior Dengue virus infection can greatly enhance Zika virus production, as a result of ADE. This can make the Zika virus infection much more severe in patients, leading to Guillain-Barré syndrome and a spike in babies being born with microcephaly.

It is possible to become immune to Zika. If a child becomes infected before they reach puberty for instance, they become immune and cannot pass the virus along to their future offspring. In parts of the world such as Africa, where the virus originated and is endemic, people are more likely to have been exposed to Zika and become immune at a young age.

However as Zika has recently been found in the Americas, an area where the virus had never been reported before 2015, it has affected adults who have never before been exposed to it, particularly women.