Hostile viruses

Researcher Berend-Jan Bosch explains why it is both difficult and important to be prepared for future outbreaks of coronaviruses

There is a close connection between the health of humans and animals, especially with regard to contagious diseases. Alongside his colleagues, Berend-Jan Bosch studies coronaviruses: a group of viruses that may occasionally jump from mammals or birds to humans. 'It remains hard to combat viral diseases, which pose a major challenge to public health and food safety.'

Coronaviruses are a common global occurrence, making up a large family of viruses that may harm numerous animal species. 'Farm animals affected by coronaviruses face issues such as retarded growth and death', said Berend-Jan Bosch, a researcher at the Department of Infectious Diseases and Immunology within the Faculty of Veterinary Medicine. 'For example, piglets with porcine epidemic diarrhoea viruses suffer severe diarrhoea and high mortality. This virus causes heavy losses in the pig sectors of Asia and America. The global poultry industry is severely impaired by the consequences of coronavirus infections as well. Fortunately, most humans with coronaviruses merely suffer from a cold. However, coronaviruses that jump from humans to animals may actually cause serious illness. Recent examples are the SARS and MERS coronaviruses, which resulted in severe respiratory infections and numerous fatalities.'

Onderzoeker Berend Jan Bosch kijkt in een model van een coronavirus dat in een doorzichtige kubus zit
Berend-Jan Bosch is examining a 'spike complex', the element used by viruses to penetrate a host cell.

Push boundaries

'If we gain a more fundamental understanding, I am convinced that we will be able to develop better vaccines and medication against viruses as well as their infections', Bosch explained. 'I therefore wish to push the boundaries of our current knowledge.' 

Together with his colleagues, Bosch is trying to comprehend the interaction between coronaviruses and their hosts, be they animals or humans. 'How do viruses infect their hosts? How do viruses avoid their hosts' immune responses? How do viruses jump from animals to humans and cause disease?' The development of antiviral drugs against the AIDS virus HIV has illustrated the large potential of such knowledge. Bosch: 'Scientists would never have been able to develop these drugs without a detailed understanding of viral biology.'


Bosch pointed out that scientists are a long way from knowing every coronavirus: 'While we have discovered dozens of species by now, we know far from all family members.'
Not all coronaviruses make their hosts ill. The main focus of the research is on the viruses that do, even though they may or may not pose a hazard to humans. 'For example, where the MERS virus barely troubles dromedaries, it may produce severe pneumonia and even death in many humans.'

Hard to predict

A range of global changes lead Bosch to suspect that there is a rising chance of new viral outbreaks. 'We see an increase in the global population, the number and transport of animals, as well as human traffic. Growing contacts between humans and animals as well as among humans pose a mounting risk of old or new viral diseases occurring and proliferating. Arming ourselves against future outbreaks is difficult, as we're unaware which virus will crop up or jump on next. Epidemiology and viral evolution are complex matters that depend on lots of factors. As a result, they are hard to predict.'

Computeranimatie van een coronavirus. Het coronavirus, rood, dringt hier binnen in de gastheercel, blauw. Hiervoor bindt het oranje eiwit zich aan het blauwe molecuul op het oppervlak van de gastheercel. Dit is de eerste stap in de infectie.
In this image, the coronavirus (red) penetrates the host cell (blue). It does so by binding the orange protein to the blue molecule on the surface of the host cell. This process is the first stage of infection.

Broad-spectrum vaccines

Bosch nonetheless stressed the key importance of attempting to prepare ourselves as best we can. 'Some viruses may spread quickly when they first jump to humans.' A case in point is Ebola. 'It does not take much to cause a large epidemic in urban areas without a vaccine or cure on the shelf.' Developing vaccines or drugs usually takes a great deal of time, which is scarce during the outbreak of a new virus.

Prevent epidemics

In recent years, there has been increasing attention among scientists to vaccines that may protect against multiple members of a virus family. 'These vaccines require us to look for similarities between viruses', Bosch explained. 'We hope that developing a vaccine aimed at such similarities will provide broad protection.' In theory, these broad-spectrum vaccines could protect us against emerging diseases. They would also be more effective against rapidly mutating viruses such as influenza. Since this virus is constantly changing, vaccines eventually become ineffective. 'We could prevent that situation by developing broad-spectrum vaccines', Bosch suggested. To do so, his research centre is collaborating with partners from academia and the industry which are affiliated to the Netherlands Centre for One Health (NCOH), the recently established Utrecht Molecular Immunology Hub as well as a European research consortium.


'We published articles on three major discoveries that we made during the past year. Such moments are amazing. It's always a joy to study viruses. Each virus depends on a host to reproduce, so they penetrate a host cell and bend it to their will in order to multiply. The way that such a tiny entity as a virus manages to do so remains an intriguing topic. At times, I see myself as a kind of explorer, curious to learn what lies beyond the horizon – beyond the boundaries of our current knowledge.'

Vetscience Nr. 4, May 2019