Tuesday, 19 April 2016 22:11

Moving to Zika Virus

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Published in Zika Diaries
 The Zika virus particle consists of a positive strand RNA enclosed in a capsid and surrounded by a membrane. Figure taken from Principles of Virology. The Zika virus particle consists of a positive strand RNA enclosed in a capsid and surrounded by a membrane. Figure taken from Principles of Virology.

I have worked on polio virus in my laboratory at Columbia University for 35 years. When that virus is eradicated--perhaps in the next few years--we will have to destroy all of our virus stocks. When that happens, I can either go home, or find another virus.

When Zika virus stepped into the world stage, we decided that this would have our post-polio virus attention.

It’s my intention to use this blog, Zika Diaries, to document our adventures through the world of Zika virus research. Each week I hope to describe our goals, findings and thoughts on this emerging virus.

Today we'll begin with the basics. 

Zika virus was first identified in Africa, first in a Ugandan monkey (1947) and then in a Nigerian monkey (1954). Over the next 50 years it became clear that humans in Africa and Asia were infected with the virus, but there were fewer than fifty confirmed cases of human Zika virus infection.

Zika virus moved outside of Africa and Asia in 2007 and 2013 with outbreaks in Yap Island and French Polynesia. The first cases in the Americas were detected in Brazil in May 2015. As of this writing the virus has spread to 52 countries. 

Zika virus is a member of the flavivirus family, which also includes yellow fever virus, dengue virus, Japanese encephalitis virus and West Nile virus. The virus particle consists of a positive strand RNA enclosed in a capsid and surrounded by a membrane (illustrated). The envelope (E) glycoprotein, embedded in the membrane, allows attachment of the virus particle to the host cell receptor to initiate infection. 

Zika virus is transmitted among humans by mosquitoes, primarily of the Aedes genus, including Aedes aegypti and Aedes albopictus. In Africa, monkeys are reservoirs for the virus, but as shown in the outbreaks, humans can also sustain transmission via mosquito vectors.

Most individuals infected with Zika virus experience mild or no symptoms. About 25% of infected people develop symptoms 2-10 days after infection, including rash, fever, joint pain, red eyes and headache. Recovery is usually complete and fatalities are rare.

Two conditions associated with Zika virus infection have made the outbreak potentially more serious. The first is development of Guillain-Barré syndrome, which is progressive muscle weakness due to damage of the peripheral nervous system. 

Zika virus caught my attention towards the end of 2015 when infection was associated with increased reports of microcephaly in Brazil. We then began a Zika virus research program that would investigate fundamental aspects of how the virus causes disease.

It’s interesting that many virologists have decided to turn their attention to Zika virus, while few worked on emerging viruses of previous years, Ebolavirus or MERS-coronavirus. Part of the reason is that Zika virus can be studied under BSL2 laboratory containment, while Ebolavirus and MERS-coronavirus require BSL4 and BSL3 laboratories, respectively. The latter are not available to many investigators. In addition, Zika virus has infected far more individuals and has the potential to spread more extensively. 

There is no doubt that scientists are opportunists, always looking for new projects that interest them and provide funding opportunities. I don’t view this as an objectionable characteristic; after all, humanity is the benefactor.

Next time: Finding Zika virus.

Last modified on Friday, 02 September 2016 11:06
Vincent Racaniello

Vincent Racaniello, Ph.D. is Professor of Microbiology at Columbia University Medical Center. As principal investigator of his laboratory, he oversees the research that is carried out by Ph.D. students and postdoctoral fellows. He also teaches virology to graduate students, as well as medical, dental, and nursing students.

Vincent entered the world of social media in 2004 with virology blog, followed by This Week in Virology. Videocasts of lectures from his undergraduate virology course are on iTunes University and virology blog. You can find him on WikipediaTwitter, Facebook, and Instagram. His goal is to be Earth’s virology professor. In recognition of his contribution to microbiology education, he was awarded the Peter Wildy Prize for Microbiology Education by the Society for General Microbiology. His Wildy Lecture provides an overview of how he uses social media for science communication.