Relatively little is known about the prevalence and transmission of human picornaviruses, a large family of viruses that can cause severe disease, and no therapy is currently available for infections. The AIROPico project aims to gain new insights into these virus infections and the diseases they cause, as Dr Katja Wolthers and Dr James Geraets explain
Picornaviruses go back under the research microscope Human
picornaviruses such as enteroviruses, rhinoviruses and parechoviruses from the Picornaviridae family mainly infect children and can cause a wide range of conditions, including respiratory disease, meningitis and encephalitis. While these viruses are the most common of all infectious agents, relatively little is known about their underlying structure and pathogenesis, an issue researchers in the AIROpico project are working to address. “We are working on human picornaviruses, in particular the enterovirus group and the parechovirus group,” says Dr Katja Wolthers, the project’s coordinator. These viruses have not always been thought to be a research priority, but Dr Wolthers believes that they require attention. “Polio for example is caused by a picornavirus. Polio viruses are nearly extinct now, because of the WHO initiative, but there are also a lot of non-polio enteroviruses out there that cause sometimes very severe diseases,” she says. “We believe that picornaviruses are an important group of viruses that need attention.” Picornavirus structure The AIROpico project is making an important contribution in these terms, bringing together researchers from the academic and commercial sectors to investigate several different aspects of human picornaviruses. The first workpackage centres around structural determination and pathogenesis of picornaviruses, with the project developing 3D cell culture models which allow researchers to study the viruses in human material. “These cell culture models are almost like very small, tiny little organs, which we can study in the laboratory,” explains Dr Wolthers. With these models, researchers can investigate
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key questions around picornaviruses, including how they enter cells and what mechanisms they use to replicate. “We have cultured human airway epithelium. We recently also managed to get human gut material to grow in the laboratory, which gives us a wonderful way to study the entry of the human picornaviruses,” continues Dr Wolthers. Researchers at the University of Helsinki are playing a central role in this work, using sophisticated techniques like X-ray crystallography and cryo-electron microscopy to image the viruses. With these techniques, researchers can analyse the structure of these picornaviruses. “We can draw a lot of important insights from seeing how a virus is made,” stresses Dr James Geraets, a post-doctoral fellow at the University of Helsinki who is also working on the project. It is possible to look at where a particular drug binds to a virus for example. “Quite a few drugs target the capsids – the outer edge of the picornavirus,” continues Dr Geraets. “By imaging that, we can potentially find out how that drug prevents the virus from operating. Does it block it binding to a receptor that it needs to access to get into a cell? Or does it simply prevent the capsid from opening up and releasing the genome?” This work is closely related to other key elements of the project’s agenda, helping build a body of knowledge which can then inform research into improved diagnosis and treatment. Current typing methods for identifying the specific virus type are quite laborious, so researchers from both the academic and industry partners are working together to develop faster methods; Dr Wolthers says there has already been significant progress in this regard. “One of our partners (TIB MolBiol)
has developed a very neat chip for human rhinoviruses, so we can see which specific type of rhinovirus is infecting the patient,” she outlines. Research is also continuing into improved diagnostic tests for other picornaviruses, some of which represent a major threat to public health. “There have been several outbreaks of infections of enterovirus D68 in recent years. It causes sudden, quite severe respiratory disease, especially in children with a pre-disposing condition like asthma. The project has developed a fast method of detecting this virus,” says Dr Wolthers. A number of diagnostic tests for other picornaviruses have also been developed within the project, notably for enterovirus A71, a virus which causes polio-like symptoms and is increasingly common in Asia. The project’s work in investigating defence mechanisms against picornaviruses takes on even greater importance in this context. “We are studying humoral immunity, and we are also interested in developing therapeutic antibodies,” explains Dr Wolthers. While the project’s research will help lay the foundations for
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