̽��ֱ�� of Cambridge - WHO Collaborating Centre for Modelling Evolution and Control of Emerging Infectious Diseases

Virus evolution and human behaviour shape global patterns of flu movement

cjb250 — Mon, 08 Jun 2015 15:00:18 +0000

In the study, an international team of researchers led by the ̽��ֱ�� of Cambridge and the Fred Hutchinson Cancer Research Center, and including all five World Health Organization (WHO) Influenza Collaborating Centres, reports surprising differences between the various types of seasonal flu virus, which they show to be due to the rate at which the different viruses evolve.

There are four types of influenza viruses that cause seasonal flu in humans: two influenza A viruses (H3N2 and H1N1) and two influenza B viruses (Yamagata and Victoria). While H3N2 viruses are the most common of the seasonal influenza viruses, H1N1 and B viruses also cause epidemics worldwide each year, hence the WHO selects representative strains of all four A and B viruses for inclusion in the seasonal influenza vaccine each year.

Importantly, all four of the viruses cause indistinguishable symptoms and evolve by similar mechanisms to escape immunity induced by prior infections and vaccinations. This ‘antigenic’ evolution is part of why people get influenza multiple times over the course of their lives.

In 2008, an international team led by scientists from the ̽��ֱ�� of Cambridge, writing in the journal Science, showed that H3N2 viruses circulate continuously in east and southeast Asia throughout the year, spreading to the rest of the world each year to cause seasonal flu epidemics. Given the fundamental similarities between H3N2, H1N1, and B infection it was thought that they would also emerge from east and southeast Asia to cause yearly epidemics worldwide. However, the work published today in Nature shows that in fact, H1N1 and B viruses behave very differently from H3N2 viruses.

Senior author Dr Colin Russell, from the Department of Veterinary Medicine at the ̽��ֱ�� of Cambridge, UK, says: “While H3N2 viruses die out between epidemics and new viruses emerge from east and southeast Asia every year, H1N1 and B viruses frequently circulate continuously between epidemics worldwide. This continuous circulation gives rise to a huge diversity in H1N1 and B viruses circulating globally.”

Interestingly, the researchers found that sometimes new H1N1 and B variants emerge from outside east and southeast Asia and are subsequently seeded into Asia, while in other cases H1N1 and B variants circulate in Asia for years without spreading globally.

“It’s really surprising to find that the H3N2 viruses are unique among the seasonal influenza viruses,” adds first author Dr Trevor Bedford from the Fred Hutchinson Cancer Research Center in Seattle, USA. “It’s almost as surprising to find that the differences among viruses are associated with a simple phenomenon: how quickly the viruses evolve antigenically.”

̽��ֱ��Nature study finds that the rate of global movement of each virus, and its ability to circulate continuously between epidemics, is shaped by how quickly that virus changes its coat to escape immunity in the human population. Viruses that evolve quickly, in particular H3N2, spread around the world rapidly, but die out quickly between epidemics. Viruses that evolve more slowly, like H1N1 and B viruses, spread around the world more slowly but are also better at circulating continuously between epidemics.

̽��ֱ��key element about global movement is who is getting infected: faster evolving viruses, like H3N2, can infect adults, who tend to travel more frequently than children, providing more opportunities for the virus to spread. Conversely, more slowly evolving viruses, such as H1N1 and B viruses, primarily infect children. Children get sick with all four seasonal flu viruses, but H3N2 evolves faster so it infects adults more often. This leads to a greater proportion of adult infections with H3N2 relative to H1N1 and B viruses, and faster spread of H3N2 viruses.

“Ultimately, this means that we can look at the viruses circulating in Asia to get a good idea of which H3N2 virus might spread worldwide, but for H1N1 and B it’s tremendously variable and the dominant variant can vary from one region of the world to another,” says Dr Russell.

̽��ֱ��Nature study also sheds important light on the role of India in the global spread of seasonal influenza viruses. Scientists and public health officials had long known that China and Southeast Asia were important for the evolution and spread of seasonal influenza viruses. However, based on the analysis of an extensive collection of viruses from India, it is now clear that India may be as central as China to the ongoing evolution of seasonal influenza viruses.

“ ̽��ֱ��focus of influenza research in the past has been on China and southeast Asia, but it seems obvious now that surveillance and public health in India, home to over one sixth of the world’s population, should be a high priority for further development to help safeguard India and the world against seasonal flu,” says Dr Mandeep Chadha of the National Institute of Virology, Pune, India.

̽��ֱ��research was primarily funded by the Royal Society and US National Institutes of Health with extensive involvement of the World Health Organization’s Global Influenza Surveillance and Response System.

Reference
Bedford, T et al. Global circulation patterns of seasonal influenza viruses vary with antigenic drift. Nature; 8 June 2015.

̽��ֱ��global movement patterns of all four seasonal influenza viruses are illustrated in research published today in the journal Nature, providing a detailed account of country-to-country virus spread over the last decade and revealing unexpected differences in circulation patterns between viruses.

While H3N2 viruses die out between epidemics and new viruses emerge from east and southeast Asia every year, H1N1 and B viruses frequently circulate continuously between epidemics worldwide

Colin Russell

Matteo Bagnoli

influenza

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Harnessing the power of research to benefit developing countries

gm349 — Thu, 25 Apr 2013 15:36:33 +0000

On Thursday 2 May, the CEO of the GAVI Alliance, Dr Seth Berkley, will discuss how to harness the power of research to expedite the development of vaccines appropriate for developing countries and improve access to them.

Dr Berkley’s talk will set out how the GAVI Alliance’s public-private partnership model brings together donors, developing countries, industry, civil society and academia to solve the challenges of reaching every child with vaccines no matter where they are born.

GAVI leverages expertise across a variety of sectors, including innovative financing for development, supply chain management, the development of mobile phone platforms for the collection of epidemiological data, mathematical modelling of infectious disease and health economics and policy.

Prior to joining GAVI in 2011, Dr Berkley was the founder, president and CEO of the International AIDS Vaccine Initiative (IAVI) for over a decade. His talk, ‘Harnessing the power of science research and the public and private sector: a 21st century model for international development’, is the Wellcome Trust-Cambridge Centre for Global Health Research’s inaugural lecture.

Dr Berkley’s talk will be followed with a presentation by the world-leading flu expert, Professor Derek Smith, Director of the WHO Collaborating Centre for Modelling, Evolution and Control of Emerging Infectious Diseases at the ̽��ֱ�� of Cambridge. There will be an opportunity for questions and answers after the talks.

̽��ֱ��evening begins at 5.30pm at the Howard Lecture Theatre, Downing College, Cambridge (map). If you would like to attend, please RSVP: http://wt-cghr-cambridge-gavi-lecture.eventbrite.com/

Professor David Dunne, Director of the Wellcome Trust-Cambridge Centre for Global Health Research and host of the lecture, said: “By partnering with globally important organisations such as the GAVI Alliance, Cambridge’s multi-disciplinary research and technology communities can have a more profound effect on international development, public health, and the lives of people in the developing world.”

“As an innovative public-private partnership, the GAVI Alliance works to harness the expertise and experience from a range of sectors to help us to improve access to lifesaving vaccines for children in developing countries,” said Dr Seth Berkley, CEO of the GAVI Alliance. “Our partners range from WHO and UNICEF to donors – including the UK government – implementing countries, vaccine manufacturers, civil society organisations, and academia.

“We have made great progress in the past decade, but the stark reality is that 22 million children born every year around the world don’t receive the immunisation they need against potentially fatal childhood illnesses. Supply chain management, improving the quality of vaccine coverage data and developing vaccines that remain highly effective outside of cold storage systems are just some of the challenges which, if they can be overcome, would have a huge positive impact on GAVI’s ability to reach more children.

“Cambridge ̽��ֱ�� has an outstanding reputation for academic research, coupled with its commitment to Africa, which makes it an ideal forum to set out the challenges and opportunities in improving access to immunisation in developing countries.”

̽��ֱ��GAVI Alliance is a public-private partnership which aims to immunise a quarter of a billion additional children in the developing world with life-saving vaccines by 2015. With GAVI support, countries are now introducing new vaccines against the primary causes of two of the biggest childhood killers in the world: pneumonia and severe diarrhoea. Together these diseases account for 30% of child deaths in low-income countries. It was established in 2000 by the Bill and Melinda Gates Foundation, the UK government and others to improve access to immunisation.

̽��ֱ��Wellcome Trust-Cambridge Centre for Global Health Research status was awarded to the ̽��ֱ�� of Cambridge in February of this year. ̽��ֱ��Centre plans to capture and capitalise on the extensive basic biomedical and health-related research capacity across many departments and research institutes in Cambridge. It will make this fully available for research capacity building and knowledge exchange partnerships with African universities and institutes, as a means of improving the health and welfare of those in low- and middle-income countries.

CEO of GAVI Alliance to give Wellcome Trust-Cambridge Centre for Global Health Research inaugural lecture

We have made great progress in the past decade, but the stark reality is that 22 million children born every year around the world don’t receive the immunisation they need.

Dr Seth Berkley, CEO of the GAVI Alliance

Harnessing the power of science research and the public and private sector

gavi_2012_olivier_asselin

Vaccinations in Ghana

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