FLUPIG

Pathogenesis and transmission of influenza virus in pigs

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 Obiettivo del progetto (Objective)

'FLUPIG aims at a better understanding of the role of pigs in influenza pandemics. Pandemic influenza viruses come from wild birds, but they must adapt to efficient replication and transmission in humans to cause a pandemic. Pigs are considered important intermediate hosts in which avian viruses adapt to mammals before they transmit to humans. However, the exact role of pigs is unclear, as is the nature of the genetic changes that are required for (a) efficient replication of an avian virus in pigs, (b) efficient transmission of avian viruses between pigs and (c) virus transmission from pigs to humans and between humans. The FLUPIG consortium will examine both the role of adaptive mutations and genetic reassortment. In addition, we will study the role of host and environmental factors in adaptation of avian influenza viruses to pigs. The occurrence and severity of a pandemic also depends on the immune status of the human population. The FLUPIG consortium will study the extent of cross-protection between antigenically different influenza viruses of the H1N1 subtype (heterovariant cross-protection), and between influenza viruses belonging to different haemagglutinin subtypes (heterosubtypic cross-protection). We will also study the immune mechanisms required for a broad cross-protection. In addition, we will evaluate the capacity of novel generation vaccines to broaden cross-protection. Most studies will be performed in pigs or other relevant animals, or in explants of the porcine and human respiratory tract, which show maximal similarity to the in vivo situation. Our studies will enable us to advice public health authorities about the role and risk of the pig in the emergence of novel influenza viruses in the human population. Combined with improved surveillance for influenza in animals, effective vaccines and antivirals, this knowledge will be critical to the control of future influenza pandemics.'

Introduzione (Teaser)

Combating flu outbreaks in humans needs a better understanding of virus transmission across species. European researchers have teamed up to provide fundamental knowledge into the role of pig hosts in influenza virus ecology.

Descrizione progetto (Article)

Flu virus strains have emerged from birds or pigs that are capable of infecting humans and causing a series of pandemics. Pigs are considered important intermediate hosts in which avian viruses adapt before they can infect humans.

Scientists on the EU-funded 'Pathogenesis and transmission of influenza virus in pigs' (http://www.flupig.ugent.be (FLUPIG)) project wish to identify the role of pigs in influenza virus adaptation. They will focus on characterising the nature of the genetic changes required for avian viral strains to replicate in pigs, as well as on understanding the mechanisms that drive transmission between the different species. Furthermore, they will describe the host and environmental factors for adaptation of avian influenza viruses to pigs.

Results so far indicate that a strain-dependent mechanism exists for transmission. When scientists performed serial passaging of the H1N1 strain in pigs they found an increase in the replication and transmission potential of the virus. This was not the case though with the H9N2 strain which required genetic reassortment with H1N1 to enhance its transmission potential.

Other determinants of efficient influenza virus transmission are being investigated including the attachment and replication in human respiratory tissue. Researchers have additionally identified the critical regions of the influenza surface haemagglutinin glycoprotein that influences viral cell binding.

The occurrence and severity of a pandemic also depends on the immune status. The consortium is therefore working to understand the extent of cross-protection between virus subtypes. This so-called heterosubtypic protective immunity has been observed in pigs previously infected with genetically related viral strains.

By providing insight into the nature of the mutations which are associated with adaptation of avian influenza virus to the pig, the FLUPIG study will help understand how novel strains arise in the human population. Through innovative approaches and critical knowledge, the consortium hopes to advise public health authorities on how to prevent influenza virus infection and pandemics.