A previous encounter with a disease that occurs throughout Latin America could leave people more vulnerable to Zika . The anti-dengue virus antibodies, a relative of Zika, can interfere with the immune system to Zika and strengthen the ability of the virus to replicate, as the work in two independent laboratories. This may help explain why the complications of Zika virus infections were more severe in Central and South America than in previous outbreaks elsewhere.
In some regions of Brazil, as much as 0% of people carry antibodies against dengue. Dengue virus there are four types, have an unusual relationship with the immune system. Antibodies that develop after infection with one type does not protect against infection with another type. Instead, the antibodies may actually help the second virus invade certain immune system cells where the virus replicates easily, making the infection worse. The phenomenon is known as antibody-dependent enhancement (ADE), and it helps explain why the most serious cases of dengue, including a very dangerous condition called hemorrhagic dengue trend fever occur when a patient catches a second type of dengue .
scientists have questioned whether the Zika virus, which is quite close to dengue to blur the results of diagnostic tests that look for antibodies, could also be close enough to cause ADE. This could help explain why Zika, who has long been thought to cause only mild disease, has suddenly been blamed for causing symptoms much worse in Brazil and elsewhere, including birth defects in babies infected in the womb and temporary paralysis called Guillain-Barre syndrome.
the first support for the theory came from a paper published on the preprint server bioRxiv in April. Sharon Isern and Scott Michael of Florida Gulf Coast University in Fort Myers and colleagues reported that two grown antibody laboratory dengue and blood serum of patients with dengue (which contains antibodies) significantly stimulated virus replication Zika in laboratory cells.
Today, in an article published online in Nature Immunology , an independent group at Imperial College London reported similar results, showing that a number of different antibodies against the dengue virus respond to Zika, but not strongly enough to neutralize the virus. Instead, when the blood plasma of patients who had recovered dengue was added to cultures of cells infected with Zika, it increased the amount of virus in cultures by as much as 100 times.
The data is convincing, says Ernesto Marques, a public health expert at the University of Pittsburgh in Pennsylvania. But clinical and epidemiological studies need to confirm that the effect plays a role in patients. There are cases of congenital Zika syndrome in babies and mothers who do not have dengue antibodies, he notes, so although dengue antibody may increase the risk of a mother passing the virus to her fetus, antibodies are not essential to cause birth defects. Studies that look for antibodies against dengue among patients Zika are complicated by the similarity of the virus, says Gavin Screaton, an immunologist at Imperial College London and an author on the Nature Immunology paper. "We desperately need" blood tests that can easily distinguish whether a patient has antibodies against dengue, Zika, or both, he said.
Even if the results are confirmed, there are not many people who have already been infected with dengue can do to protect themselves, but reduce the risk of mosquito bites, eg using repellent . But these precautions are already recommended for everyone in affected countries Zika.
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