Sunday, 19 February 2017

Does studying yellow fever offer Zika clues?


As cases of Zika virus increase there is considerable investigation and research into the virus. One area being looked at for clues is yellow fever virus. A second area involves the use of mouse models.

By Dr. Tim Sandle

Zika virus is a member of the Flaviviridae virus family. In one in four people the disease causes a mild illness known as Zika fever, for up to seven days. The symptoms include fever, rashes, joint pain and conjunctivitis. The biggest risks are infected women and babies born with abnormally small heads and brain defects, a condition called microcephaly.
Yellow fever and Zika viruses have a common characteristic in how they can circumvent an insect’s immune response. This is due to the viruses manufacturing proteins that can suppress the immune response in the host. A similar response occurs in people, when we become infected.
For this reason, researchers have been studying mosquitoes and viral infections. This is based on using gene drive, a method targeting specific genes. The idea is to tip the battle at the genetic level in favor of the mosquito. This tranche of research could eventually lead to a human vaccine.
A second wave of research, also from Texas A&M University, College Station, is finding a means to make an infective mosquito undergo altered behavior so that it will not seek out humans to infect.
The research has been published in the journal Proceedings of the National Academy of Sciences. The paper is titled “Yellow fever virus capsid protein is a potent suppressor of RNA silencing that binds double-stranded RNA.”
In a second wave of research, a different group of researchers are seeing whether mice with healthy immune systems could provide new insights into Zika virus pathology and treatment. This is not straightforward due to the changes that animals undergo when they are infected. Mice, however, can, under certain conditions, be used as ideal models for Zika virus research.
The reason for focusing on mice is because studies have indicated that young mice with specific immune system defects are susceptible to Zika infection. By rearing mice (coded C57BL/6) with functioning immune systems that can be successfully infected with Zika, more detailed studies can be made and to provide the basis for testing treatments.
The second research study has been published in the journal PLOS Pathogens. The paper is headed “Zika (PRVABC59) Infection Is Associated with T cell Infiltration and Neurodegeneration in CNS of Immunocompetent Neonatal C57Bl/6 Mice.”