Efficient transmission of swine-adapted but not wholly avian influenza viruses among pigs and from pigs to ferrets.
BACKGROUND
Pigs are considered to be intermediate hosts for the transmission of avian influenza viruses (AIVs) between birds and humans, but the transmissibility of AIVs among pigs and from pigs to other mammals remains largely unexplored.


METHODS
In an initial study, we confirmed the replication potential of various low-pathogenic AIVs in pigs and ferrets, which we used as a model for humans. We then examined the transmissibility of 6 selected low-pathogenic AIVs among pigs (by direct contact) and from pigs to ferrets (by air contact).


RESULTS
Although H1N1 and H3N2 swine influenza viruses spread readily from inoculated pigs to contact pigs and ferrets, evidence for AIV transmission was extremely rare. The fact that infected pigs shed lower amounts of AIVs than of swine influenza viruses may contribute to the reduced transmissibility of AIVs.


CONCLUSIONS
Our data indicate that swine-adapted influenza viruses spread readily among pigs and from pigs to other susceptible mammalians and support the notion that AIVs undergo genetic adaptation to efficiently cross the species barrier. Our transmission models hold potential to study the factors that lead to the generation of pandemic influenza viruses.
De Vleeschauwer
Annebel
A
Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium.
Van Poucke
Sjouke
S
Braeckmans
Debby
D
Van Doorsselaere
Jan
J
Van Reeth
Kristien
K
D000818:Animals; D001717:Birds; D005289:Ferrets; D009980:Influenza A virus / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000276:immunology; D005585:Influenza in Birds / Q000635:transmission* / Q000821:virology*; D008969:Molecular Sequence Data; D009976:Orthomyxoviridae Infections / Q000662:veterinary* / Q000821:virology; D017422:Sequence Analysis, DNA; D013552:Swine; D013553:Swine Diseases / Q000635:transmission* / Q000821:virology*