Immune response to Zika virus may harm fetal development: Study

A study has recently revealed that the proteins that mount a potent immune response to Zika viral infection can affect the placenta and fetal development.

A study has recently revealed that the proteins that mount a potent immune response to Zika viral infection can affect the placenta and fetal development. These antiviral proteins, known as type I interferons, are required to fight Zika infection in mothers. But the role of interferons in providing an immune defence for the fetus is still not clear.

The team lead Akiko Iwasaki from Yale University studied two different types of mouse models -- one type lacked the receptor for type 1 interferon altogether and the other had only one copy of the interferon receptor gene. The results revealed that the latter group showed signs of abnormal placental development, restricted fetal growth, and death. The finding demonstrates that the damaging effects of the immune response to Zika virus can outweigh the benefits for fetuses, said the researchers, noting that although type 1 interferon is critical to blocking replication of the virus, too much of it can be detrimental during pregnancy.

The study results may have implications for other infection-related pregnancy complications and possible interventions. The research is published in Science Immunology journal. Recently another research on an experimental Zika vaccine developed by US scientists has been found in two early clinical trails to be safe and promising in preventing infection by the deadly virus. The findings, published in the journal Lancet, showed that it induced an immune response in healthy adults. The investigational vaccine, developed by scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the US National Institutes of Health, includes a small, circular piece of DNA called a plasmid. Scientists inserted genes into the plasmid that encode two proteins found on the surface of the Zika virus.

The researchers found that when the vaccine was injected into muscle, the body produced proteins that assemble into particles that mimic the Zika virus and trigger the body to mount an immune response. For clinical testing, the researchers developed two different plasmids - VRC5288 and VRC5283. They were tested in two separate trials. The scientists analysed blood samples obtained from participants four weeks after their final vaccinations. They found that 60 to 89 per cent of participants generated a neutralising antibody response to VRC5288, whereas 77 to 100 per cent of participants generated a neutralising antibody response to VRC5283. "Following early reports that Zika infection during pregnancy can lead to birth defects, NIAID scientists rapidly created one of the first investigational Zika vaccines using a DNA-based platform and began initial studies in healthy adults less than one year later," said NIAID Director Anthony Fauci. "NIAID has begun Phase 2 testing of this candidate to determine if it can prevent Zika virus infection, and the promising Phase 1 data published today support its continued development," Fauci said on Monday.