Pathogenesis and transmission of influenza virus in pigs

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 re-assortment. 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.